ARAB REPUBLIC OF EGYPT

Ministry of Housing, Utilitiesand Urban Communities

Housing and Building Research Center

;.'

EGYPTIAN CODE OF PRACTICEFOR

STEEL CONSTRUCTION AND BRIDGES(ALLOWABLE STRESS DESIGN)

Code No. (205)Ministerial Decree No 279 - 2001

Permanent Committee for the Code of Practicefor Steel Construction and Bridges

First Edition2001

)

~;>11>"""~)~:;.)1)'

~1~1,:,u..~l,,~l.,J.IJ,jI.S:....~1

.Jo:!h.ll~

1"uUJ ))

I •• ! l..c.J (,V~l e'J~hJ~.J~ l.Y"-"'J ~.r--Jl Jpj\ 0~

~.lw\ LSJ4-<JIJ ~w..w\

i..:-'1..,..,J\ w~J J~\.rJ\_1 w~~\ ...':d.'

. ,,~1 JL...c\J ;~w..j'!\ <",IL.c)!\ ~.6Jy.l.J ~~\ d~ ~ \ '\'\ t :i...i..J '\ ~J (,lJoiLilJl ~.t~'¥\ J,,"!

~\J F-~\J D~~j -:...?-! jSyJ :lAWI~\ ww. ~ , Wv :i..i....J t'\ i..3; ;YJJ~\ t.,."'<:lJ; ).,r-.!~ J

. u-i1y...J\

~'\-":"~'\ J~il ~ .kJ~J~lJ"""~ ~)1 ~l~ \'\",i W t'\'f ~J loS)]}\ j.i'JI c,...-\c;

. f\..i~\ J~\j

J\JC1 W\..I.!\ ~\~d~ \ '\'\v W \ i \ riJ(,$Jlj."l1 )fl.) \ '\At .w 'r'Ar ~J ,SJU.J11 ;1.>;11 ~_~

. ~.ur,..JIl.S~IJ~~\ ~bJ~J~(..""""'~ LSy.a.J1.l.FJl

....,.J.~ L~j I J.#i.l.l\ ~li.•.h\ ~~~J J~ WlJ.ll ~l ~J! JY5JlI ~w,...~\ ~l o- :i...~i\ ;j-5w~J

• F-1..i.:J\J Lits....·,P ~J'-':l jS.)A ;).1)

I •• \ / \-/\'\,,; J~

CA(,,-\ r :I) ,-.-J

J~

\ 1\0 ~J ",SJ\jyl .;I.).Jl.,. 0JJt.....:J1J ~.lI.tJ\ l.SJ4S-lIJ <.:J~I j~ .hJ~J l~ 0""""1 J.lf......;j

, t¥~l ~~ lSJl.,ls..~J ";'Wowl~ bJ;JoJI~ U""""'J LS~\ J~ \ '\ '\ /I. ;Lc."J

. 'fill 14! ,I.,. L.~ \'" l..c.J , ~J w...U.I ..,.i oJ";..]!)~I~I e.>'!'

c.l;i! -\U.lM..l\ LS.J4S-IIJ u~\ ~ hJ~J~ u--~ 15~\ J.,Pll ~1.1.1\ ~\ u-ljij\~,~ 1A)~l ~ ~~\ ~J ~~ ~u..1 ~J WS ~.u.:.., ~ LJi 1.Al.fl~ ~J...:J\

. 'fil' w-,1fi-'; ~

W" ...:'i i,$~\ .lft.l~ ~4- 1.4 ~~ t? J...,tJ\ ~ll jw......l\ ~~.J u\S-~\ <!.JJ~ j-Sj'l ~...t~•

.~ ~JJ:J1J ~ ~p\j ~jjiJ Ity1.iJ~I tSJ4"l'J ,.::..l~' ~.bJ~J~.

.~l ~):l LJ-" lj!U ~,-}J ~jl e-"uJIl~ J.>il\ \~ .)'~.~

,J ~-4'.)~

j .... ..:..;,::..- (- )C\,. 0>J '\ '/;JV I

: (') ;,L.

: (I) ;,L.

: {rl "k

: (t) "L.

PREFACE

In 1989, the Ministerial Decree NO.239 was issued for the EgyptianCode of Practice for Steel Construction and Bridges. Later, in 1998, arevised edition of the same code was updated and issued under theMinisterial Decree No. 185, 1998.

This new present version of the code accounts for the additions andchanges that were necessary. Some materials considered to be lessapplicable to current construction practices have been deleted orreduced in scope. However, new material has been added in thisversion. The additions and changes include:

Geometric limitations of members to avoid premature bucklingunder different types of straining actions are introduced.

- Connections are treated in more details.Upgrading of some topics such as composite construction andmaterials related to cold-formed sections

All designs of structural steel in building construction and bridges areto conform to this code.

Minister of Housing, Utilities& Urban Communities

Prof. Dr.!

Committees for the Egyptian Code of Practice forSteel Construction and Bridges

(Allowable Sress Design)

The Permenant Consulting Committee

Prof. Dr. Ahmed A. MoharramProf. Dr. Mohamed H. KhorshidProf. Dr. Mosatafa A. Swelam

The Permenant Technical Committee

Prof. Dr. Adel H. Salem - ChairmanProf. Dr. Kamal Hassan MohamedProf. Dr. Gamal EI-Din NassarProf. Dr. Mohamed N. EI-AtrouzyProf. Dr. Hamdy A. A. MohsenProf. Dr. Hassan A. OsmanProf. Dr. Bahaa MashalyProf. Dr. Metwaily Abo-HamdProf. Dr. Fayrouz F. EI-DibProf. Dr. Nabii S. MahmoudProf. Dr. Hussein H. Abbas

Committees

Ain Shams UniversityAI Azhar UniversityAlexandria University

Ain Shams UniversityAin Shams UniversityAin Shams UniversityAin Shams UniversityAin Shams UniversityAin Shams UniversityCairo UniversityCairo UniversityHBRCMansoura UniversityAI Azhar University

The Technical Subcommittees

1- For Fatigue:

CONTENTS

Page

Dr Ashraf OsmanDr. Ahmed FaroukDr. Ashraf M. Fadel

2- For Stability and Slenderness Ratios:

Dr Ezz Eldin YazidDr. Ahmed Abdel SalamDr. Abdel Rehim Badawi Abdel Rehim

3- For Plate Girders:

Cairo UniversityCairo UniversityHBRC

Ain Shams UniversityAin Shams UniversityAin Shams University

CHAPTER 1 : MATERIALS

1.1 General1.2 Identification1.3 Structural Steel1.4 Grades of Steel1.5 Cast Steel1.6 Forged Steel1.7 Cast Iron1.8 Wrought Iron

11223344

5- For Cold Formed Sections and Dimensional Tolerances:

4- For Composite Steel-Concrete Construction:

Prof. Dr. Abdelrahim Khalil DessoukiDr. Abdel Rehim Badawi Abdel Rehim

Dr. Moheeb Abdel GhafarDr Sherif Saieh Safar

Prof. Dr. Abdelrahim Khalil Dessouki

6- For Technical Editing:

Prof. Dr. Abdelrahim Khalil DessoukiDr. Ashraf M. Fadel

Ain Shams UniversityAin Shams University

Cairo UniversityCairo University

Ain Shams University

Ain Shams UniversityHBRC

CHAPTER 2 : ALLOWABLE STRESSES

2.1 General Application 62.2 Primary and Additional Stresses 62.3 Secondary Stresses 72.4 Stresses due to Repeated Loads 82.5 Erection Stresses 82.6 Allowable Stresses for Structural Steel 82.7 Effective Areas 272.8 Allowable Stresses in Standard Grade

Structural Steel 282.9 Allowable Stresses In Cast and Forged Steels 282.10 Allowable Stresses in Bearings and Hinges 312.11 Area of Bearings or Bed plates 34

CHAPTER 3 : FATIGUE

Committees

3.1 Scope3.2 Basic Principles

Comenn I

3536

5.1 Weldability and Steel Properties 685.2 Structural Welding Process 685.3 Thermal Cutting 715.4 Distortion 735.5 Design of Butt (Groove) Weided Connections 745.6 Design of Fillet Welded Connections 815.7 Plug and Slot Welds 885.8 General Restrictions to Avoid Unfavourable

Weld Details 915.9 Weld Inspection Methods 92

PageCHAPTER 7 : PLATE GIRDERS

7.1 General 1227.2 Allowable Stresses and Effective Cross-

Sections 1227.3 Web Plate Thickness 1227.4 Web Stiffeners 1247.5 Splices 1267.6 Unsupported Length of Compression Flange 1267.7 Deflection 126

CHAPTER 4 : STABILITY AND SLENDERNESSRATIOS

4.1 General4.2 Maximum Slenderness Ratios4.3 Buckling Factor

CHAPTER 5 : STRUCTURAL WELDING

Page

515152

CHAPTER 8 : TRUSS BRIDGES

8.1 General8.2 Spacing and Depth of Trusses8.3 Minimum Thickness8.4 Compression Members8.5 Tension Members8.6 Lacing Bars, Batten Plates and Diaphragms8.7 Splices and Connections

127127128128129130130

CHAPTER 9 : COMPLEMENTARY REQUIREMENTS FORDESIGN AND CONSTRUCTION

CHAPTER 6 : BOLTED CONNECTIONS

6.1 Material Properties 946.2 Holes, Clearances, Washers and Nuts

Requirements 956.3 Positioning of Holes for Bolts and Rivets 976.4 Strength of Non-Pretensioned Bolted

Connections of the Bearing Type 1006.5 High Strength Prestressed Bolted Connections

of the Friction Type 1036.6 Allowable Shear Rupture Strength 1116.7 Additicnal Remarks 1126.8 Hybrid Connections 1146.9 The Determination of the Prying Force (P) for

Prestressed High Strength Bolted Connections 114

9.1 General for Buildings and Bridges9.2 Steel Buildings9.3 Steel Bridges

CHAPTER 10 : COMPOSITE STEEL-CONCRETECONSTRUCTION

10.1 Composite Beams10.2 Composite Coiumns10.3 Composite Beam-Columns

131140144

152177181

Contents II Contents III

PagePage

CHAPTER 11 : COLD·FORMED SECTIONS

11.1 General11.2 Classification of Elements11.3 Maximum and Minimum Thickness11.4 Properties of Sections11.5 Maximum Allowable Flat Width-Thickness

Ratios for Compression Elements11.6 Maximum Allowable Web Depth-Thickness

Ratios for Flexural Members11.7 Maximum Allowable Deflection11.8 Allowable Design Stresses11.9 Effective Widths of Compression Elements

with an Edge Stiffener or an IntermediateStiffener

11.10 Beams with Unusually Wide Flanges11.11 Compression Members11.12 Tension Members11.13 Cylindrical Tubular Members11.14 Splices11.15 Connections

CHAPTER 12 : DIMENSIONAL TOLERANCES

183183183183

184

185185186

186192193194194196196

13.4 Quality Assurance13.5 Contracts

CHAPTER 14 : INSPECTION AND MAINTENANCE OFSTEEL BRIDGES

14.1 General14.2 Inspection14.3 Maintenance of Steel Bridges

242245

249249246

12.1 General 21412.2 Types of Tolerances 21412.3 Application of Tolerances 21512.4 Normal Erection Tolerances 21512.5 Permissible Deviations of Fabricated Elements 21612.6 Permissible Deviations of Column Foundations 21712.7 Permissible Deviations of Erected Structures 218

CHAPTER 13: FABRICATION, ERECTION AND FINISHINGWORKS

13.1 General Provisions13.2 Shop Fabrication and Delivery13.3 Erection

229230235

Contents IV Contents V

A

Ao

A,

A,

A,

a,

NOMENCLATURE

Gross cross-sectional area of boll; cross-sectional area ofa member (crrr').Parameter for calculating the effective area to be used forcalculating the axial strength for cylindrical tubularmembers.Bending modification factor; net area of connected leg ofthe section; area of shear connector's front face; bearingarea on composite columns at connections.Bending modification factor; area of unconnected leg ofthe section; bearing area on concrete for shear connector'bearing area on composite columns at connections. 'Area of concrete section without haunches; net area ofconcrete in composite columns (em').Effective area for calculating axial strength of circulartubes (ern").Effective stiffener area (crrr).Area of compression flange (crrr).Cross-sectional area of column considered in alignmentcharts (ern"). .Area of lon~itudinal reinforcement bars in compositecolumns (cm ).Tensile stress area of bolt; cross-sectional area of steelbeam, column, pipe or tubing; cross-sectional area ofanchor or hoop connector; reduced area of the stiffener(em').Effective area of the stiffener (ern').Cross-sectional area of stud connector (crrr).Net shear area for H~h Strength Bolts (H.S.B.) (ern"),Area of stiffener (cm ).Net tension area for High Strength Bolts (H.S.B.) (ern').Constant, the log of which depends on the detail categoryin fatigue; distance between the U-frames; bolt outeroverhanging dimension with respect to the stem Tee stub;minimum transverse distance between the centroids ofwelding, bolt groups, or rivets of battened or latticedcompression members; center to center spacing ofsleepers.Deviation of the center line for anchor bolts within the

B.

BL

b

b

bo

group of bolts at any column base; spacing of transversestiffeners.Deviation in distance between two adjacent columnsmeasured at the base of the steel structure; spacing oftransverse stiffeners.Sum of single deviations in a row of columns measured atthe base of the steel structure.Maximum permissible deviations.Distance between the centers of consecutive main girdersconnected by the U-frame (cm).Reduction factor for allowable shear stress forconnections with bolts passing through packinqs.Reduction factor (for allowable shear and bearing stressesfor bolts) for long joints.Flange width of stiffened compression elements; width ofangle leg; height of T-section; overall or inside plate width;bolt inner overhanging dimension with respect to the stemTee stub; half the center to center distance of steel beamsin composite sections; width of tube section; width offlange for girders and columns (em).Unsupported width defined in Table 2.1; flat width ofstiffened compression element or sub-element in cold­formed sections (cm).Overall width of an element with an intermediate stiffener(ern). .Plate width; half the center to center distance of steelbeams in composite sections; smaller width of concrete­filled rectangular tube (em).Flat width of a stiffened compression element having onelongitudinal edge connected to a web or flange elementand the other stiffened by a stiffener (ern).Distance from edge of concrete slab to center of end steelbeam; larger width of concrete-filled rectangular tube(em).Flat width of a stiffened compression element with bothlongiludinal edges connected to other stiffened elements(cm).Beam width (cm).Width of slender plate elements in compression (em).Effective width of concrete slab acting with steel beam(cm).

Nomenclature VI Nomenclature VII

NomenclatureIX

,width for slot welts and slotted bolt holes; nominaldiameter of a fastener; longitudinal distance center tocenter of battens; visible diameter of outer surface of arcspot weld; width of arc seam weld; flat width of an edgestiffener; depth of channels (ern).Spacing of transverse stiffeners; distance from thecentroid of the compression chord to the nearest face ofthe cross girder of the U-frame (em).Distance from the centroid of the compression chord tothe centroidal axis of the cross girder of the U-frame (ern).Average diameter of arc spot weld or arc seam weld (ern).Flange beam depth (ern),Effective diameter of fused area of arc spot weld or arcseam weld (ern).Depth of haunch; diameter of a standard hole (cm).Minimum hole diameter for plug welds; minimum slotwidth for slot welds (ern).Total depth of concrete slab including haunch (ern).Stud shear connector diameter; reduced effective width ofthe stiffener (ern).Effective width of the stiffener according to Table 2.4 (ern),Clear depth of web; larg"~ of the screw head diameter orwasher diameter; depth of the flat portion of the webmeasured along the plane of the web in cold-formedsections (ern).Modulus of elasticity of steel (lIcm').Modulus of elasticity of concrete (lIcm').Modified Young's modulus z E, (lIcm').Youn~'s modulus of steel in composite construction(lIcm ).Pitch of shear connectors; distance measured in the lineof force from the center of a standard hole \0 the ilearestedge of an adjacent hole or to the end of t~e connectedpart towards which the force is directed (ern).End distance from the center of a fastener tothe adjacentend of any steel element measured In the direction of loadtransfer; positional deviation of parts connected to a girderor column; positional deviation of adjacent end plates ofgirders.Edge distance from the center of a fastener to theadjecent edge of any steel element measured at right

Nomenclature

e,

e

d.dmin

d,dbd.

d,

VIII

Effective width of slender plate elements in compression'effective width of the concrete flange on each side of thecenter iine of the steel beam in composite sections'effective design width determined for single-stiffenedcompression element (ern).Segment widths of the effective width of slender plateelements In compression; effective width of the concreteflange on each side of the center line of the steel beam incompositesections (em).Effective design width of element or sub element ofmuttiple-stiffened compression eiements (cm).Right and left effective width portions of the concrete slabrespectively (em). 'Compression flange width (ern),Width of steel flange connected to the concrete forcompositesections (ern).Width of horizontal column stiffener (cm).Width of slender plate elemets in tension (cm).Outstanding flange width; compression force' fiat width ofunstiffened compression eiements in 'coid-formedsections.Flat width of unstiffened compression elements in cold­formed sections; coefficient for calculating the portion ofthe effective Width next to the stiffener.Flat width of unstiffened compression elements in cold­formed sections; coefficient for calculating the portion ofthe effective Width away from the stiffener = I,ll,.Bending coefficient; compression force in connectedflange due to beam moment (M).Moment modification factor.Design force for intermediate transverse stiffeners;centroid of steel section.Centroid of composite section.Numerical coefficients for the design of compositecolumns.Outer diameter of the tubular member; total horizontalshear force to be transmitted by one shear connector incomposite sections; outer diameter of circular compositecolumn; overall depth of an edge stiffener.Depth of web; overall depth of the section; diameter of aroller or pin bearing; hole diameter for plug welds; slot

d

C,

CmC,

C,

be1•

b.,

b.

Nomencfature

Allowable compressive stress for circular tubes (lIcm').Allowable stress range for fatigue (vcm].Maximum stress range for fatigue (t1cm ).Allowabie stress in axial tension (t1cm').Allowable tensile bolt stress (t1cm').Allowable tensile stress for rupture (t1crn').Allowable tensile stress on the net section of a bolted

~~t~~~~~os~r~~~~~)~f steel (t1cm')Tensile strength of member in contact with the screw head(t/crrr').'fensile strength of member not in contact with the screwhead (t/crrr'). ,Ultimate tensile strength for bolts (t1cm ~.

Ultimate tensiie strength for rivets (tlcrn ).Yield stress of steel; yield stress of stud shear connectors(t/crn"). ,Yield stress for bolts (t1cm ).Modified yield stress z Fy (t1cm'). "Yield stress of longitudinal reinforcing bars (tlcm<).Yield stress of anchor or hoop material; yield stress of thebar in angle shear connectors (t1cm'). .Axial stress; actual stress in cold-formed compre~slon

flange; design stress in the cover plate or sheet (lIcm ).Normal stress perpendicular to the axis of the weld(t1cm').Bigger compressive stress at end of plate element; lateraldeflection of girder.Lateral deflection of compression flange of girder, relativeto the weak axis, between points which will be lateraliyrestrained on completion of erection.Tensile or smaller compressive stress at end of plateelement (tlcm').Actual stress in lip stiffener (t1cm').Average bending ~tress in the flange of the full unreducedflange width (tlcrn"). 2

f b , Calculated compressive stress (t1crn ).f

b", Actual compressive bending stresses based on moments

fbcy about the x and y axes, respectiveiy (t1cm').f bIX, Actual tensile bending stresses based on momemts aboutf bty the x and y axes, respectively (t1cm').

Nomenclature XI

f,

f"

r,f~

f

F"

F,F"Fsra

Ft

FIb

Ft,

Ftt

x

angles to the direction of load transfer; positional deviationof a column base in relation to the column axis throughthe head of the column below.Distance from the axis of a slotted hole to the adjacentend or edge of any steel element; positional deviation ofbearing surfaces.Distance from the center of the end radius of a slottedhoie to the adjacent end or edge of any steel element(em).Minimum distance measured along the line of applicationof force from the centerline of a weld to the nearest edgeof an adjacent weld or to the end of the connected part;minimum distance measured in the line of force from thecenter of a standard hole to the nearest edge of anadjacent hole or to the end of the connected part towardswhich the force is directed (ern).Unmtentional eccentricity of girder bearing.Allowable stress (VCITl'). .

Allowable bearing stress on concrete of compositecolumns (t/crrr').Allowable stress In bending; allowable bearing stress forbolts (t/cm').Allowable compression stress in bending not covered by2.6.5.1 - 2.6.5.4 (t/crn').Allowable compressive bending stresses based onmoments about the x and y axes, respectively (lIcm').Allowable tensile stress in bending (Vern').Allowable tensile bending stresses based on momentsabout the x and y axes, respectively (t/crrr').Allowable stress in axial compression (t/crn').Allowable crippling stress (t/crrr'),Flexural buckling stress of circular tubes (t/crrr').Modified elastic buckling stress for buckling in x and ydirections. respectively (tlcm').Euler stress divided by a factor of safety for buckling in thex and y directions, respectively (t/crrr).

Permissible stress for all kinds of stresses for fillet welds(Ucrn2

) .

Lateral torsionai buckling stresses (tlcm').

Fbt:Xl

Fbc:y

FbI

Fbtx ,

Fbty

F,Fc:rp

F,Femx1

Femy

FEx1

FE'Fltt"Fltb11

Fltb2

Fpw

eoFall

Fapp

e~in

Nomenclature

Height between points which will be laterally restrained.Larger concrete width of concrete encased l-section;height between floor slabs in a multi-storey building.Height between floor slabs in a multi-storey building.Height of column cross-section; column length withintenmediate components; level of bearing surfaces onsteel columns.Depth of steel beam (em).Depth of web of girders and columns (em).Moment of Inertia of a section (ern').Second moment of area of the vertical member fonmingthe anm of the U-frame about the axis ·~f bending (em").Second moment of area of the cross girder of the U-frameabout the axis of bending (em'). .Adequate moment of inertia of the stiffener so that eachcomponent element can behave as a stiffened element

(ern"). . .Moment of inertia of the column considered In thealignment charts (ern').Minimum moment of inertia of the full stiffener about itsown centroidal axis parallel to the element to be stiffened(em"). .Moment of inertia of the full section of the stiffener aboutits own centroidal axis parallel to the element to bestiffened (ern").Moment of inertia of composite section about thecentroidal axis of the composite. section (cm').Moment of inertia of one channel about its centroidal axisnormal to the web (ern"),Moment of Inertia of the chord member about the Y-Y axis(ern"),Minimum energy for Charpy V-notch test (joules).Effective length factor for buckling of a member;coefficient relating throat to size in fillet welds.Modified value and value determined from the alignmentcharts for the buckling length factor, respectively.Effective buckling length; buckling length, bigger of in­plane and out-of-plane buckling lengths (ern),Effective length factor for buckling of a member, flangethickness plus fillet of rolled section; flange thickness plusweld size of built-up I-sections; coefficient for the applied

XIIINomenclature

JK

KL,K!, k!k

Iy

I,

I,

I,

Im1n

h,hwI1,

XII

Applied bending stress based on moments about the xand y axes, respectively, and neglecting composite action(t/crrr').Actual compressive stress due to axial compression;actual compression stress due to axial "orce computed onsteel section only in composite columns (t/crrr').Actual crippling stress (t/crrr').Characteristic cube concrete strength (28 days cubecompressive strength of concrete, kg/cm').Equivalent stress (lIcm').Effective stress in welds (t/crrr').Deflection of column between floor slabs.Deflection of column between points which will be laterallyrestrained on completion of erection.Maximum a~tual bearing pressure at the surface ofcontact (t/crrr) ..Actual tensile stress due to axial tension (t/crrr').Bending stress in the upper-most fibers of concrete slab(t/crn).Bending stress in upper and lower fibers of steel beamrespectively (t/crn"). 'Maximum bow of web for girders and columns and plategirders with intermediate stiffeners.Shear modulus of steel; ratio of summation of (IlL) forcolumns to summation of (IlL) for girders for the alignmentcharts.Factors used in the alignment charts to determinebuckling length factor.Gauge of holes in consecutive lines for calculatinq the netarea; length of gap between intermittent longitudinalwelds; spacing between rows of fasteners measuredperpendicular to the direction of load transfer' verticaldistance between the two rows of connectors nearest tothe top and bottom flanges (em).Overall height of the building.Height of section; width of angle leq; length of intermittentlongitudinal welds; total depth of composite section; singlestorey floor height.Smaller concrete width of concrete encased l-section:height between floor slabs; level of top of floor slab; floorheight under consideration.

h,

G

fus, tis

fmax

Hh

L,

L,

1

I,

M

torque for pretensioning of H.S.B.Buckling factor for shear.Plate buckling factor.Length of span; unsupported length for tension orcompression members; span of the truss; overall length ofthe. fillet weid; .iength of hoop shear connector; length ofseam weld not including circular ends; iength of fillet weld;length of flare groove weld; overall length of the building.Clear distance. between effective lengths of consecutivechained intermittent fillet welds (ern).Clear distance between effective lengths of consecutivestaggered intenmittent fillet welds (em).Length of shear connector (em).Distance betw~en centers of end fasteners in a joint (em).Length of end intermittent fillet weid (em).Effective laterally unsupported length of the compressionflange (ern).For columns, actual unbraced length of member; bearinglength (length of roller or pin); length of truss member; forbe.ams, distance between cross-sections braced againsttwist or lateral dlspiacement of the compression flange'length of cantilever beam; length of slot for slot welds andslotted bolt holes; unbraced iength of lacing bar (ern).Overall dimensions of building.Effective buckling length of the compression chord ofbndge trusses; total length of girder.Length between points which will be laterally restrained.Length of diagonal In multiple intersected web trapezoidaltruss system (em).Distance between two adjacent columns measured at thebase of the steel structure.Distance between adjacent steel columns at any level.Distance between adjacent girders.Length of a battened or latticed compression member forbuckling about the y-y axis (ern).Maximum unsupported length of the compression memberbetween lacing bars or batten plates (em).Bending moment; magnification factor.

M, Smaller moment at end of unbraced length of beam orbeam-oolumn; induced bending moment in end plate(cm.t).

M, Larger moment at end of unbraced length of beam orbeam-column; induced bending moment in end plate(cm.t).

M. Applied torque to H.S.B.M

oMaximum bending moment for a simply supported stringer(crn.t).

m Constant that depends On the detail capacity in fatigue;distance between shear center and mid plane of web.

N Axial force, tension or compression; number of loadingcycles or stress cycles.

Nl Larger value of compression force in the intersected websystem of the K-truss (tl·

N. Smaller value of compression force in the intersected websystem of the K-truss (tl·

n Length of base plate; number of shear planes in fasteners;total number of bolts resisting the extemal tension force;number of parallel planes of battens; modular ratio =E,JE,; number of floors.

P Prying force; force transmitted by an arc spot weld; load orreaction (t).

p. Allowable load on arc spot weld; allowable load on arcseam weld; allowable load on fillet weld; allowable load onflare groove weld (t).

Pci Axial compressive strength of the ith rigidly connectedcolumn (t).

Pnot Allowable pull-out strength per screw (t).Pn., Allowable pull-over strength per screw (t).Pn• Allowable shear strength per screw (tl·Pn; Allowable tension strength per screw (tl·P, Safe frictional load (tl.p Center to center distance between holes for plug welds

and slots for slot welds and slotted bolt holes in thedirection of the slot width (em).

p' Center to center distance between slots for slot welds andslotted bolt holes in the direction of the slot length (cm).

Q Shear force; transverse shear force (tl·Q"t Maximum vertical shear at the stiffener position (t).Qb Allowable shear force per H.S.B. (t).

Nomenclature XIV Nomenclature

Nomencfature XVII

web area (em).Radius of gyration wilh respect to x-x axis (em).Radius of gyralion with respect 10y-y axis (ern).Minimum radius of gyralion for Ihe z-zaxis of one part of abattened or latticed compression member (cm).1.28(ElFy) 112

Spacing belween centers of fasteners in the outer row oftension members (ern),Spacing between centers of fasteners in Ihe inner rows oftension members (ern). .Slaggered pitch of holes for calculating Ihe net area.; sizeat fillel weld; spacing between centers of fasteners In thedirection of load lransfer (cm).Leg sizes of fillet welds (em). .Maximum permissible longitudinal spacing of connectors(cm). .Tension force; axial pretension force in the bolt shank (I).Tension force in connected flange due 10 beam moment(M) (I).Charpy V-nolch lestlemperalure.Applied external lension force (I).Induced extemallension force per boll (t).Maximum induced tensile force due to the appliedmoment (M) per boll (I).Tensile slrenglh of connectors (I). .Thickness; throal of fillet weld; plate Ihickness; smalleslconnected thickness; total Ihickness of connected parts;Ihickness of reinforced concrete slab neglecling haunchIhickness, if any; IotaI combined base steel Ihlckness ofsheets involved in shear Iransfer (cm).Plate thickness; thickness of member in contact with Ihescrew head (ern).Plate Ihickness; thickness of member not in contact w~hthe screw head (em).Flange beam Ihickness (ern),Width of outstandmq leg of shear connector; lesser of Ihedeplh of penetration and Ihe thickness of Ihe member notin contact w~h Ihe screw head (ern).Flange Ihickness; compression flange Ihickness (cm).

. Thickness of column flange (em).Thickness of packing; Tee stub flange or end plate

Nomenclature

t,

r.,T.xt

.T.xt,bText,b,M

T.t

s

S.21,,0

r,ryr,

XVI

Shear stress: inlensily of load.Shear stress perpendicular 10Ihe axis of Ihe weld (Vern').Shear stress along Ihe axis of the weld (Vern').Calculaled shear stress in plate girder (Vern').Allowable stress in shear (Vern').Allowable buckling stress in shear; allowable shear stressfor bolls (Vern').Allowable shear stress for rupture (Vern').Reaction or concentraled load applied 10 beam or plalegirder; radius of slot for slol welds and slotted boll holes;inlemal radius of cold-formed sections.Honzonlalload supported by anchor (I).Bearing strength of a single bolt (t).Allowable horizontal load transmitted by bearing for blockshear connectors (I).Horizontal load supported by hoop (I).Allowable horizontatshear load for one shear connector(I).Design shear strength per bolt (t).Actuai shearing force in the fastener due 10 the appliedshearing force (t).Tensile strength of a single bolt (I).Actual lension force in Ihe faslener due 10 Ihe appliedlension force (I).Allowable horizonlal load provided by the shear connectorconnection to Ihe beam flange (I).Governing radius of gyration; radius of cylinder or sphere;radius of fillel; radius of hoop shear conneclor; forcetransmitted by boll or bolls at the section considered,divided by the tension force in the member at that section.Bigger radius of cylinder or sphere (em).Smaller radius of cylinder or sphere (em).Raduis of gyration of one channel about the centroidalaxis parallel to web (em).Raduis of gyration of I-section about the axisperpendicular to the direction in which buckling wouldoccur (em).Radius of gyration of steel shape, pipe or tubing of acomposite column (em).Radius of gyration about minor axis of a sectioncomprising the compression flange plus one sixth of the.

r,

r

q,R

R"Rsh.a

Vh1

Vhp1,

Vhp2

VwVwl

w

w

xyy'

y,

y,

a.

thickness (em).Thickness of concrete slab (em).Thickness of horizontal column stiffener (em).Web thickness; effective throat of fillet weld; effective sizedimension for flare groove welds (em).Thickness of column web (em).Maximum load on bearing (t).Inclination of column in a multi-storey building measuredfrom the column base.Inclination of column in a multi-storey building betweenadjacent floor slabs.Inclination of column in a single-storey residential building.Inclination of column of a portal frame in an industrialbuilding.Inclination of web between upper and lower flanges.Eccentricity of the web in relation to the center of eitherflange.Depth of filling of plug and slot welds; flange Tee stubbreadth with respect to one column of bolts (em).Half breadth of end plate or half breadth of Tee stubflange (em).Width of the flange projection beyond the web, or half thedistance betweenwebs of multiple web sections (em).SUbscript relating symbol to x - axis bending.Subscript relating symbol to y-axis bending.Distance of neutrai axis from the top of the slab of thecomposite section when the neutral axis falls inside theslab and the concrete in tension is neglected (em).Distance between centroidal axis of concrete section andthat of the composite section (em).Distance of central axis of steel section from the top of theconcrete slab in composite sections (em).Coefficient of thermal expansion of steel; stressdistribution factor for plastic stress distribution; ratio ofdimensions of web panels between transverse stiffeners;coefficient for the allowable bearing stress in fasteners(bolts); rotation in degrees of the bolt nut after the snug fit;angle in vertical plane between anchor or hoop and thebeam upper flange; coefficient for allowable axialcompressive stress of composite columns for the case ofinelastic buckling; coefficient for calculating effective

ai,

I;

"o

stiffener area.Reduction factor for long fillet welded lap joints; slopeangle of concrete haunch; angle in horizontal planebetween anchor and longitudinal axis of the beam.Safety factor with regard to slip.Inclination of flanges of welded plate girders.Deviation from level of top of floor slab.Deviation in length of prefabricated components to befitled between other components; deviation of level ofbearing surfaces on steel columns (crane girder level).Deviation in distance between adjacent steel columns ataiiylevel.Deviation in length of prefabricated components to befitled between other components; deviation in distancebetween adjacent steel girders at any level.Flexibility of the U-frame (em).Ratio of bearing area on concrete to area of connectorfront face.Angle of inclination of diagonal stiffener in connections;angle of inclination of lip stiffener in cold-formed sections.Slenderness ratio = (KUr).

1/2Parameter = (FylF.) .Maximum slenderness ratio.

Normalized plate slenderness.

Web slenderness parameter.Friction coefficient (slip factor).Poisson's ratio of steel.Mass density of steel; reduction factor for width of slenderplate elements. .'Summation of height between floor siabs In a rnutti-storeybuilding.Axial compressive strenjth of all columns in a storey (t).Deviation in overall heigt i of the building.Deviation in overail lenqt.: of the building at any level.Diameter of hoop shear connector; diameter of the barwelded to angle shear connectors (em).Ratio of smaller compressive or tensile end stress tolarger compressive end stress in web or flange elementfor elastic stress distribution.

Nomenclature XVIII Nomenclature XIX

I

\

CHAPTER1

MATERIALS

1.1 GENERAL

Steel structures shall be made of structural steel, except whereotherwise specified. Steel rivet shall be used for rivets only. Caststeel shall preferably be used for shoes, rockers and bearings.Forged steel shall be used for large pins, expansion rollers and otherparts, as ~pecified. Cast iron may be used only where specifically

authorised.

The materials generally used in steel construction are describedbelow. Special steels can be used provided that they are preciselyspecified and that their characteristics, such as yield stress, tensilestrength, ductility and weldability, enable the present code to be put

into application.

1.2 IDENTIFICATION

1.2.1 Certified report or manufacture(s certificates, properlycorrelated to the materials used, intended or other recognisedidentification marl<.ings on the product, made by the manufacturer ofthe steel material, fastener or other item to be used in fabrication orerection, shall serve to identify the material or item as to specification,

type or grade.

1.2.2 Except as otherwise approved, structural steel notsatisfactorily identified as to material specification shall not be usedunless tested in an approved testing laboratory. The results of suchtesting, taking into account both mechanical and chemical properties,shall form the basis for classifying the steel as to specifications, andfor the determination of the allowable stresses.

Materials 1

1.3 STRUCTURAL STEEL

The mechanical properties of t ctrequirement given in Clause 1 4s ~ndurai steel shall comply with thetemperatures, calculations shall'b~ made~ f~~~agl r~~~dltl~nts °lf usuaion the following properties. so s ee based

Mass Density D 7.85 t/mModulus of ElasticityShear Modulus

E = 2100 t/cm-rG 810 t/cm-r

Poisson's RatioCoefficienl of Thennal Expansion

1) - 0.3C1. = 1.2 x ~ 0" 1°C

1.4 GRADES OF STEEL

Malerial conforming 10 the E r ..NO.260171 (Ministry of Industry) is a gyp land fStandard Specificationpprove or use under this code

1Nominal Values of Yield Stress Fy and Ultimate Strength Fu

Grade ofThickness t

Steel t ~ 40 mm 40 mm< t ~100 mm

Fy F, Fy F,It/em') (t/em') (t/em') It/em')

5137 2.40 3.60 2.15 3.4

5144 2.80 4.40 2.55 4.1

5152 3.60 5.20 3.35 4.9

1.5 CAST STEEL

1.5.1 Steel caslings shall be of one of the two following grades inaccordance with the purpose for which they are to be used, asspecified on the drawings and as prescribed in the special

specification.

a- Castings of grade C 51 44 for all medium-strength carbon steelcastings; for general use and in parts not subjected 10 wearing on

their surfaces.

b- Castings of grade C 51 55 for all high-strength-carbon steelcastings which are to be subjected to higher mechanicalstresses than C 5144; for use in parts subjected 10 wearing on theirsurface such as pins, hinges, parts of bearings and machinery of

movable bridges.

1.5.2 Steel for castings shall be made by the open-hearth process(acid or basic) or eiectric furnace process, as may be specified. Onanalysis it must show nol more than 0.06% of sulphur or phosphorus.

1.6 FORGED STEEL

1.6,1 The following "rcscripUons apply to carbon steel forging for

parts of fixed and movable Lr.<!ges.

The forging shall be of the 101Ic'",ing grades according 10 the

purpose for which they are USed:

a- Forging of grade F 51 50, 0"",ea"1<1 or nonnalised; for mild steelforging of bearings, hinges, tn',"";'''' . shafts, bolts, nuts, pins, keys,screws, worms. Tensile strenMIl from 5.0 to 5.6 Ucm'; minimum yield

point stress 2.4 Ucm'.

b- Forging of grade F 51 56, normai,;>ed, annealed or normalised andtempered; for various earncn steel macllinery, bridge and structuralforgirg of pmions, levers, cranks, rollers, tread plates. Tensilestrength from 5,6 to 6.3 IIcm2; minimum yield point stress 2.8 Ucm'.The grace required shall be specified on Ihe plans or in the special

specificalion.

Materials 2 Materials 3

1.6.2 Carbon steel for forging shall be made by the open hearth or anelectric process, acid or basic, as may be specified.

The steel shall contain not more than 0.05% of sulphur or ofphosphorus, 0.35% of carbon, 0.8% of. manganese, 0.35% ofsilicium. .

1.7 CAST IRON

1.7.1 Where cast iron is used for such purposes as bearing platesand other parts of structures liable to straining actions, it shall complywith the following requirements.

Two test bars, each 100 cm long by 5 cm deep and 2.5 cm wide,shall be cast from each melting of the metal used. Each bar shall betested being placed on edge on bearings 100 cm apart, and shall berequired to sustain without fracture a load 1.40 ton at the centre witha deflection of not less than 8 mm. Cast iron of this standard strengthshall be named CI 14.

1.7.2 Where cast iron is used for balustrades or similar purposes,in which the metal is not subjected to straining actions, no specialtests for strength will be called for.

1.7.3 All iron castings shall be of tough grey iron with not more than0.01% sulphur.

1.8 WROUGHT IRON

Wrought iron, where employed in existing structures shall complywith the following requirements:

a- The tensile breaking strength of all plates. sections and flat barsshall in no case be less than 3.5 tlcm'.

b- The yield point stress of all plates, sections and flat bars shall in nocase be less than 2.2 tlcm'.

c- The elongation measured on the standard test piece shall be notless than 12%.

of rivets and bolts, in case it is notd- The ultimate shear strengtht the material oflhe said rivets and

'ble to perform a tensile tes on 2

~~~~I, shall in no case be less than 3.0 tlcm .

Matenals 4 Materials5

Stresses which are the result of eccentricity of connections andwhich are caused by direct loading shall be considered as primary

stresses.

The induced stresses in the floor members and in the wind bracingof a structure resulting from changes of length due to the stresses inthe adjacent chords shall be taken into consideration and shall be

considered as secondary,

Bending stresses in the verticals of trusses due to eccentricconnections of cross-girders shall be considered as secondary.

In ordinary welded, bolted or riveted trusses without sub-panelling,no account usually needs to be taKen of secondary stresses in anymember whose depth (measured in the piane of the truss) is lessthan 1/10 of its length for upper and lower chord members, and 1115for web members. Where this ratio is exceeded or where sub­panelling is used, secondary stresses due to truss distortion shall becomputed, or a decrease of 20% in the allowable stresses prescribedin this code shall be considered (see also Clauses 8.4.4, 8.4.5, and

853)

Secondary stresses are usually defined as bending stresses uponwhich the stability of the structure does not depend and which areinduced by rigidity in the connections of the structure alreadycalculated on the assumption of frictionless or pin-jointed

connectIons.

Structures shouid be so designed, fabricated, and erected as tominimize, as far as possible, secondary stresses and eccentricities.

2.3 SECONDARY STRESSES

The design should then be checked for case \I (primary +additional stresses), and the stresses shall in no case exceed theaforesaid allowable stresses by more than 20%.

2.2.3 In designing a structure members shall, in the first instance, beso designed that in no case the stresses due to case 1 exceed theallowable stresses specified in the present code.

CHAPTER 2

ALLOWABLE STRESSES

2.1 GENERAL APPLICATION

. The following prescriptions .stipulated In the special specific~~i~ether with any other provisionsdesign and construction of steel bed ns, are Intended to apply to the

1 ges and buildinqs.

The structural safety shall b .stresses produced in all arts ae es~abl'shed by computing theexceed the atlowable (working) st nd ascertaininq that they do notparts. are subjected to th resses specified herein, when thesecombinations of the loads e dm~st unfavourable conditicns orEgyptian Code of Practice ~~r L~~~es according to the currentElements. In applying the said s and Forces for Structural~eth~ds of design shall be used, b~~~c~;Ftlons, approved scientific

ey shall In no case exceed tbe r it h .ons shall be computed and_ urn s erern after specified

2.2 PRIMARY AND ADDIT'ONAL S .I TRESSES

2.2.1 For the purpose of com ' +structure, the straining actions _h~.U~lng tne maximum stress in a

, i oe calculated for two cases'

Case I: Primary Stresses Due to .

Dead Loads -> Live Loads or S+ Centrifugal Forces. upenmposed Loads + Dynamic Effects

Case II: Primary and Additional Stresses Due to

Case, i -> (Wind Loads or Earth uak .S~OCK Effect, Change of Te;" e~a~~rads, Braking Forces, LateralBearinqs, Settlement of S P . e. Frictional Resistance fShnnkage and Creep of conc~~fe~rts In addition to the Effect ~f2.2.2 Stresses due to Wind .such t Loads shall be co ids ructures as towers tra S ,_ .. nSI ered as primary' foretc. ,l' n mISSIon poles, wind bracing systems

Allowable Stresses 6Allowable Stresses

For bracing members in bridges, the maximum allowable stressesshall not exceed 0.85 of the allowable stresses specified in this codeif the bridge has not been considered as a space structure.

2.4 STRESSES DUE TO REPEATED LOADS

Members and connections subject to repeated stresses (whetheraxial, bending, or shearing) during the passage of the moving loadshall be proportioned according to Chapter 3.

2.5 ERECTION STRESSES

Where erection stresses, including those produced by the weightof cranes, together with the wind pressure, would produce a stress inany part of structure in excess of 25% above the allowable stressesspecified in this code, such additional material shall be added to thesection or other provision made, as is necessary, to bring the erectionstresses within that limit.

2.6 ALLOWABLE STRESSES FOR STRUCTURAL STEEL

2.6.1 General

Allowable stresses for structural steel shall be determinedaccording to the grade of steel used. Structural sections (subject tothe requirements in Clause 2.7), shall be classified (depending on themaximum width-thickness ratios of their elements subject tocompression) as follows:

1- Class 1. (compact sections):

Are those which can achieve the plastic moment capacity withoutlocal buckling of any of its compression elements.

2- Class 2. (non-compact sections):

Are those which can achieve the yield moment capacity withoutlocal buckling of any of its compression elements.

The limiting width to thickness ratios of class 1 and 2 compressionelements are given in Table 2.1.

Table (2.1a) Maximum Width to Thickness Ratios for StiffenedCompression Elements

(a) Webs: (Internal elements perpendicular to axis ofbending)

JtJf!Jffh{P:.:" iw1 t. t 11

. dw=h-3t. {t-:trtwl

Web Subject to Web Subject to Web Subject 10 BendingClass/Type Bending Compress;on and Compression

f~TF, JJrTfG1 1 - ad'

L'h1. Compact d h d. - h d.

{-~ 1- 1. JL +_ 1-

Stress distribution F, F,F,

inelement.

(Not forsingle ex = 0.5 a = 1.0 a> 0.5 a <05channel)

~<699/..fF; d.<6~~~~ &.~~ I." «:I." -IF.: I." -IF.: t ..-c 13a . t

Y, Y

F, F,

r I'Td'i

f fG T2.Non-Compact l- -- h d - h d. h

1,.I_i" J L 1. L - 1.Stress distribution

F, t F,inelement. F,

t 0 ·1 t 0 1 t >.1 ~~-1

~<~d. 64 '!,,( 1901 -IF," d. 9511-i>1-{f

T ~ -IF.: T"~ -IF.I.' --IF; • F, t w" 2+1J.' • F,

Aflowabfe Stresses 6Allowable Stresses 9

Table (2.1b) Maximum Width to Thickness Ratios for StiffenedCompression Elements

for

a

Maximum Width to Thickness RatiosUnstiffened Compression Elements

Table (2.1c)

(c) Outstanonq Flanges:

~I =r:e E:[ ==orf

Flange SubJeciFlange Subject toCompression and Bending

ClasslType toCompressionTip inCompression TIP inTension

~Fy,ac,1.Compact

~-I -F

~-il +,+Stress distribution \L- I \!-C--j \!-c--jin element.

" C,

Rolled f~16.9,J~ zrc <1&" YF::" <:YC <".9'-taF::I t If" Y tl" y

Welded ~ ~ 'S3l-¥F;"' ~~~15.31~ ~ c <\S3I-taF::f -c ,

2. Non-Ccmpact

~. - IFy F~Stress distribution ~ " +in element.

l.--j f--c--j I'--C--!, C-----

Roiled ~ ~ '~-¥F;"' ~~35 -Q;

Welded ~~ '1I-¥F;"' ~~32 "/k(JIFy

Fork see Tables 2.3&2.4

"1-~"--

I

Section inCompresslOOSection inBendirg

1. Compact

Siess distributioninele'nent andacross section.

. " 2fY In vern

(bl Internal Flange Elements: (Inlemal elements parallel 10 axis ofbending)

=-FI fl ~. flO}

E...<~ E...<~11"£ II"~

"y

I

i.· rj I IFy Fy2. Non-Compact .

:1 A"II I,' \

" II I I!,I !1" 1-;u II " IIStess dlstribution II ;1 +1 II II I 'inelement and l-'o===-:J =i I!o===--!J ~=;

across section.

-,E...<~E...<_'_.

II" -rr- If" ~i Y

AIIowab!e Stresses 10

Allowable Stresses 11

2.1..•....•...•...••..••.••.• , .......••.......... ,....

Grade q.II (tlcm')

of Steel t ~ 40 mm 40 mm < t:.:;;: 100 mm

SI37 0.84 0.75

SI44 0.98 0.89

St52 1.26 1.17

Grade F, (tlcm')

of Steel t ~ 40 mm 40 mm < t" 100mm

St37 1.4 1.3

St44 1.6 1.5

5t52 2.1 2.0

On the effective net area as defined in Clause 2.7.1:

The .effective area in resisting shear of rolled shapes shall betaken as the full height of the section times the web thickness whilefor fabricated shapes it shall be taken as the web height betweenflanges times the web thickness.

q.lI =0.35 Fy .•••• 2.2

2.6.3.1 On the gross effective area in resisting shear as defined

below:

2.6.3 Allowable Stress in Shear q.lI

2.6.2 Allowable Stress in Axial Tension Fl

When any of the compression elements of a cross-section isclassified as class 3, the whole cross-section shall be designed as aclass 3 cross-section.

Are those which cannot achieve yield moment capacity withoutlocal buckling of any of its compression elements.

3- Class 3. (slender sections):

1\i,

Ratios for

(') For unequal leg angles2

Fy in Vern

(d) Angles: ll--b-1 . (Does notapply to

tl~l angles incontinuousI h contact withother

..L components)

ir-- tClass Section In Compression

FYI - I.Stress distribution

~nFyacross section

--11-- t

Non-compact blt~231~: (bthI12t~ 17f-./Fj n

Class Section InCompression

(e) T-Section: rr. Fy

--11--1Non-compact bit ~ 301,jfv"

(f)Tubular Section: V}Class Section InBending and/or

Compression

1. Comoact Oft ~ 1651 FY

2. Non-Compact Olldl11Fy

Table (2.1d) Maximum Width to ThicknessCompression Elements

Allowable Stresses 12 Allowable Stresses 13

..

2.15

2.12

2.13

2.14

2.11

2.10(0.35 Fy ) .0.9Aq

Fe ~ 7500/A'

For A ~ klJr "100:

. (0.58Fy -0.75) 2Fe =0.58Fy - 4 A

10

For all grades of steel:

Aq z 1.2

Grade Fe (tlcm')

of Steel t ~ 40 mm 40mm<t~ 100mm

5137 F, ~ (1.4 - 0.000065/.') F, ~ (1.3- 0.000055/.')

5144 F, ~ (1.6- 0.000085/.') F, ~ (1.5 - 0.00007SA')

5152 F, ~ (2.1 - 0.000135/.') F, = (2.0 - 0.00012SA')

For compact and non-compact sections, the full area of thesection shall be used, while for slender sections, the effective areashall be used, as given in Tables 2.3 & 2.4.

For X. ~ slenderness ratio ~ klfr < 100 (see Chapler 4 for definition

of terms):

. On the. gross section of axially loaded symmetric compressionmembers (having compact, non-compact, or slender sections) inwhich. the shear center coincides with the center of gravity of thesection and meeting all the width-thickness ratio requirements of

Clause 2.6.1:

2.6.4 Allowable Stress in Axial Compression Fe

2.7

2.5

2.6

2.4

2.3

For stiffened webs:

~>45,~lw VFy

For unstiffened webs, a = '" kq = 5.34

2.6.3.2 Allowable Buckling Slress In Shear qb

Depending on the web slenderness parameter:

'A. =dltw ~q 57 Vk q

kq =Buckling factor for shear

=4 + (5,34fa'), for a'; 1

= 5.34 + (4/a'J, for a > 1

Where: a = d,/d & d, =Spacing of transverse stiffenersd =Web depth

Where:

In.~dd~tjon, the shear buckling resistance shall also be checked asspecified In Clause 2.6.3.2 when:

For unstiffened webs:d 105->-tw jF;

The buckling shear stress is:

For Aq '; 0.8

0.8 < Aq < 1.2

qb = 0.35 Fy .

qb = (1.5 - 0.625 Aq)( 0.35 Fy )

2.8

2.9

In case of sections eccentrically connected to gusset plates(e.g., one angle), unless a more accurate analysis is used, theallowable compressive stresses shall be reduced by 40% of Fein

case the additional bending stresses due to eccentricity are not

caiculated.

Allowable Stresses 15Allowable Stresses 14

In order to qualify under this section:

1- The member must meet the compact section requirements ofTable 2.1.

2.6.5 Allowable Stress in Bending Fb

:,6.5.1 T<;nsion and compression due to bending on extreme fibers ofcompact sec~lons symmetric about the planeof their minoraxis and

bent about their major axis:

2.19.................................................Fb = 0.72 Fy

1- Tension FbI

2.6.5.5 On extreme fibers of flexural members not covered by Clauses

2.6.5.1 - 2.6.5.4:

Fb = 0.58 Fy 2.21

2.6.5.4 Tension and compression on extreme fibers of box-typefiexural members meeting the "non-compacl" section requirements ofTable 2.1b, and bent about either axis:

Fb =0.64 Fy 2.20

2.6.5.3 Tension and compression on extreme fibers of rectangulartubular sections meeting the compact section requirements of Tables2.1a & 2.1b, and bent about their minor axis:

2.6.5.2 Tension and compression due to bending on extreme fibersof doubly symmetrical I-shape members meeting the compact sectionrequirements of Tables 2.1a & 2.1c, and bent about their minor axis;solid round and square bars; solid rectangular sections bent about

their minor axis:

Where b, is the compression flange width, M,/M, is the algebraic ratioof the smaller to the iarger end moments taken as positive for reversecurvature bending, d is the beam depth and Cb is given in Equation

2.28.

2.17

2.16Fb = 0.64 Fy

Grade Fb (t/crn")of Steel t ~ 40 mm ac mm e t c 100mm

5t37 1.54 1.38

5t44 1.76 1.63

! 5t52 2.30 2.14

2· The laterally unsupported length (L,) of the compression flange islimited by the smaller of:

i- For box sections:

Lu

< ~>f }Or

Lu ';(137+84~~) bf/Fy

Hence, FbI is taken as follows:

Grade Fbdl/cm')

of Steel t ~ 40 mm 40 mm < t ~ 100 mm

5t37 1.4 1.3

5t44 1.6 1.5

5t 52 2.1 2.0

ii- For other sections:20b fLu ~--s:

Or1380A ft., < CbdFy

2.18

Fbl=0.58 F, ...•...•...•...•... , ....•.....•....•............ 2.22

Allowable Stresses 16 Allowable Stresses 17

2- Compression Fbc b

I. When the compression flange is braced laterally at intervalsexceeding L" as defined by Equations 2.17 or 2.18, the allowablebending stress in compression Fbc will be taken as the larger valuefrom Equations 2.23 and 2.24, 2.25, or 2.26 with a maximum valueof 0.58 Fy:

i- For shallow thick flanged sections, where approximately

tfL u(I)d > 10), for any value of Lofrr, the lateral torsional buckling,stress is governed by the torsional strength given by:

ii- For deep thin flanged sections, where approximately

(tfL" .b,d < 0.40), the lateral torsional buckling stress is governed by

the buckling strength given by:

ICba· When Lu IrT < 84~F.; , then:

~,=O~~ 2~

800Fllb, = Lu.dl A, c, s 0.58 Fy ..

ICb &b- When 84~F.; ,; i., I'T S 188VF.;

, then:

(Lu IrT )2 FyFilb = (0.64 )F S 0.58 Fy

2 1.176x10 5Cb Y

c- When Lu I'T >188~, then:

12000Filb = c, s 0.58 Fy

2 (L u IrT)2

2.23

2.25

2.26

,,,,,,,,"/I

Lr,:,:,:'::-':__~-:::::1

Alternativ!,ly, the lateral torsional buckling stress canbe computedmore accurately as the resultant of the above mentioned two

components as:

2 2Fflb

= F,tb,

+ Fllb,

S 0.58Fy 2.27

In the above Equations:L

uEffective laterally unsupported length of compression

flange.= K'(distance between cross-sections braced against twist or

lateral displacement of the compression flange in cm).K = Effective length factor (as given in Chapter 4).'T = Radius of gyration about the minor axis of a section

comprising the compression flange plus one sixth of the

web area (em).A, (b,' t f) Area of compression flange (em').b

lCompression flange width (cm).

d = Total depth (em).Fy = Yield stress (tlcm').t, = Compression flange thickness (em).c, = Coefficient depending on the type of load and support

conditions as given in Table 2.2. For cases of unequal endmoments without transverse loads, (Cb) can be computedfrom the expression:

Cb

= 1.75 + 1.05 (M,/M,1 + 0.3 (M1/M,)2 S 2.3 ..... 2.28

Allowable Stresses 18 Allowable Stresses 19

2.30

2.29...................800Fit, = c, s 0.58 r,

Lu.dl A,

ka

= Plate buckling factor which depends on the stress ratio 4'as shown in Tabies 2.3 and 2.4-

b = Appropriate width, (see Table 2.1) as follows:

andI

p~ normalized plate slenderness given by:

Ip

= ~: ~................................. 2.31

M,

(~)

III. Slender sections which do not meet the non-compact sectionrequirements of Tabie 2.1 shall be designed using the sameallowable stresses used for non-compact sections except that thesection properties used in the design shall be based on the effectivewidths be of compression elements as specified in Tabie 2.3 forstiffened elements and Table 2.4 for unstiffened elements. The

effective width is calculated using a reduction factor p as be = P bwhere:

II. Compression on extreme fibres of channels bent about their majoraxis and meeting the requirements of Table 2.1,

When the bending moment at any point within the unbraced lengthis larger than the values at both ends of this length, the value of (C,)

shall be taken as unity.

Where:(M,/M,l is the algebraic ratio of the smaller to the larger end momentstaken as positive for reverse curvature bending.

Loading8end~ngMoment I End Restraint I Effective

Diagram About Y-axisLength C b

Factor K

,M M) [[]]]] Simple 1.0 1.00C

, Fixed 0.5 1.00,

M

~Simple 1.0 2.30

( M)Fixed 0.5 2.30

1'! I ill! 11 Simple 1.0 1.13

"1]J]IiY Fixed, 0.5 1.00

~I I! I I ~ U ISimple 1.0 1.30

Fixed i0.5 0.90

I

I~I

Simple ! 1.0 1.35

.. Y ..Fixed 0.5 1.07

~I

~ Y Simple 1.0 1.70

YI Fixed

;0.5 1.04

r---J ~ Warping

" 1.0 1.50. Restrained

~ II I; II I I ~ Restrained 1.0 2.10

I

Table (2.2) Values of Coefficients K and C,

Alfowable Stresses 20 A/fowabla Stresses 21

2.6.6 Allowable Crippling Stress in Web F",

On the web of rolled shapes or built-up l-sections, at the toe of thefillet. the allowable crippling stress shall not exceed:

Web crippling is a localised yielding that arises from highcompressive stresses occurring in the vicinity of heavy concentratedloads.

23

(2.3) Effective Width and Buckling Factor for StiffenedCompression Elements

Effective Width be forStress Distribution p=(X,-0.15-0.05o/)1 X;.,;l

For 1 >1jf~-1:16

k = [(1 +~)2+ 0.112(1-0/ flO.5+(1+0/)~1>'I'>·2

(J

f2/ r, 1 1>1f>0 0 O>yJ>·1 -1~

Buckling k 8.27.Bl 7.81-6.29o/+9.7Bo/ 2 23.9 5.9B(1-~ )24.0 1.05+ 0/Factor (T

f f2

0/=I:

1

11D11 be = P b, .; .'

be b 2 ' bel =0.5 beII: 1.: b !. e:1 b e2" 0.5 be

f 1I> o/!:-O:

ILaI f

2 be =pb

bel =2 be/(5 - 0/ )P b l.be2

: I be2 = b - bele

f 1gl 0/<0:--~t: be = pb c =P b/(l-~)

r~' I~e~i f2bel =0.4 be

be2 =0.6 beI b .1- 1

Allowable Stresses

Table

2.32

JEL k

tw "T

-'-kr,

n+2k

n+Js-,

F,,,, = 0.75 Fy

I" •

,J

= dw for webs= b for internal fiange elements (except rectangular hollow

sections)= b-3t for flanges of rectangular hollow sections

= C for outstanding flanges

= b for equal leg angles

= b or (b+h)/2 for unequal leg angles

= b for stem of T-section= relevant thickness

Grade I F,~ (Vcm')of Steel , t:o::; 40 mm 40 mm < t :s 100 mm

St 37 I 1.8 1.6

5t 44 i 2.1 1.9

5t 52 I 2.7 2.5

bb

bb

b

bbt

Allowable Stresses 22

-The crippling stress (f,,,,) at the web toes of the fillets resulting

from concentrated loads (R) not supported by stiffeners shall becalculated from the following Equations:

2.35

2.34

2.33

A,=A,=1.0

for edge loads .

for interior loads

Actual compressive stress due to axial compression.The allowable compressive stress, as appropriate,prescribed in Clause 2.6.4.The actual compressive bending stresses based onmoments about the x and y axes, respectively.The allowable compressive bending stresses for the xand y axes, respectively, considering the memberloaded in bending only as prescribed in Clause 2.6.5.The Euler stress divided by a factor of safety forbuckling in the x and y directions, respectively (t1cm').

Where:f" =F, =

fbcx, f oey =

Fbc;oFbcy =

FEx, FEY =

For cases when f"f F, < 0.15,otherwise:

2.6.7.1 Axial Compression and Bending

Members subjected to combined axial compression (N) andsimple bending moment (M) about the major axis, shall beproportioned to satisfy the following interaction Equation:

2.6.7 Combined Stresses

Stress DistributionEffective Width be for

p= (X,-0.15 -0.05'1') I~ ~ 1

'I' = f 2 I f 1 1 1> V' >0 a 0>0/>-1 -10.578

1.70 1.7-5V!+17.1\V2 23.8Buckling factor k (J 0.43 1/1 + 0.34

~1> r;:-O:

If , '. I

"', - f 2be =pC

b 'eber:

'I'<0:f 1~

be b,f 2 be = pbe = PC/(1-'I')

I--C~

'I' = f 2 I f 1 1 a -1 1>1JI >-1

Buckling factor k a 0.43 0.57 0.85 0.57-0.21'1' +0.07 '1'2

@/.I" ] > 0/:>0:f 2 ,I. -

, "

C----Ibe =pC

b, be

'~f1 'I'<0:

f 2

, be = pbe = PC/(1-'I')-b;"I--C----,

Table (2.4) Effective Width and Buckling Factor For UnstiffenedCompression Elements

Allowable Stresses 24 Allowable Stresses 25

2.39

27

g ~i;:~i~:u~e~ti;:~st~~ t~i~t~~\meaSUred at right angles to theconsecutive lines. mer, centre to centre of holes in

Allowable Stresses

t = The thickness of the material.

Where:s = The staggered pitch, i.e., the

distance, measured parallel tothe direction of stress in themember, centre to centre ofholes inconsecutive lines.

f. =~f2 + 3q2 ,,1.1 Fall

2.7 EFFECTIVE AREAS

2.7.1 Effective Net Area

The effective net sectional-area of a tension~~~t~ ~hl~a~~ea :s the :um of the products of the ~~~~:~ss::~ n~~member For e emhen as measured normal to the axis of the

. '. a c am of holes extending acros .

~:J~~~gO;r~'~Z~~eli~~~st:~nd~~~~~hs~~t~~ f~rt~Sh~1 ~e ~~~i~:da~~In the chain and adding for e h e iarneters of all holes

. 2 ,ac gauge space In the chain thequantity (s /4g). '

~xes,. respectively, considering the member loaded inending only as prescribed in Clause 2.6.5.

In addition, the compressive bending stresschecked against the lateral torsional buckling stress. alone shall be

2.6.8 Equivalent Stress f.

Whenever the material is subjected to axial and h tthe equivalent t sear s ressesgiven in this c~~:ss I~fe) m.ust not exceed the permitted stresse~calculated as fOIiOW/ s 10V., and the equivalent stress shall be

2.38

2.37

2.36

Actual tensile stress due to axial tension.The allowable tensile stress prescribed in Clause

2.62The actual tensile bending stresses based onmoments about the x and y axes, respectively.The allowable tensile bending stresses for the x and y

26FbtxlFblY

Allowable Stresses

Where:fta =Ft

2.6.7.2 Axial Tension and Bending

Members subjected to combined axial tension "N" and bendingmoment "M" shall be proportioned to satisfy the following conditions:

Cm

=Moment modification factor, and is to be taken according to the

following:a- For frames prevented from sway without transverse loadingbetween supports C

m= 0.6 - 0.4 (M,/ M,) > 0.4 where the end

moments M1 and M2 carry a 3ign in accordance with the end

rotational direction; i.e., positive moment ratio for reverse curvatureand negative moment ratio for single curvature (M2 > M1)'

b- For frames prevented from sway with transverse lateral loading

between supports, Cm may be taken as:

i- For members with moment restraint at the ends, Cm = 0.85.

ii- For members with simply supported ends, Cm = ~ .0.

c- For frames permitted to sway, Cm=0.85.

In addition, sections at criticai locations, e.q., at member ends,

shall satisfy the following Equation:

~-"-'- ...._--------:-----.,...

2.7.2 Gross Sectional-Area

2.9 ALLOWABLE STRESSES IN CAST AND FORGED STEELS

2.9.2 The allowable stresses in forged steel of the grade FST 56 shallnot exceed the allowable stresses given In Table 2.6.

11 ~

.~°11.....

= U!~ ~ v

o C- ... 0

;; ",0

C> .50

~~a.

e ~ID.

~ .0.."• "tJ:':~ ~ .C ..9~~ o.:!° ~c

• ;~p:::

U .,.J:~

J:1na. " ..g .~

w"y .0C 08;0C

~~i; .0e- 0-,.; • C

0.0.,; "E01 C.!! '"~ 0 "" [~ '"~ • .;=.!! .. Gr r.tI~N 0 N

~ 0vc>

"0• C

~ afi= =s 11 G _00 ~ID

"0,~

~ "'~0 2 0

E ~ btl= c C c

! ~ E o~o.e ~ 'Vi~ • '3 UO~

;; e- .¥~~

'" eC w·

~0

~ '"C

;; C vO

0 '" i ~ u• !- v

~= c ...

" ..1 "6 ° o'ri'

~C ;; -a~• '" .w• C

~ j~~

C ,2-e ~ j~ .~

_.=° 11 ~f! ~... ....!l. a• ~

i~~

.!! U ~ ";!i J;~ • ia. p 8 .... :l!• g .... .'M v S ".il j• v• i;

.ui; .~

0 o~ ~J:u, ... ... 0 ... III -e- i! !! 5t: ~;- •

C ~': ,g ~or ... .. ..• 0 ~ E m "! ~11;: ~~ .,; 0

In '. -e-

"Cc~e .S!::S' »I'llCAcu.-

.§~~~N5 ~ ~-e-

~~; I~e...

1- 0 06 11.

I °e"Cl"O N .ccg;->ol'llo·_I1._g'~-g ~NE ... .. 0

~ ~ ~

'iii Q,I 11l ci .!:!: "" "" ...c ... al ,, =-GjC. O DI- E _ lL.

00 -E

0

~ "" ~- GlC> ::

~ """ "-.S "' a "" .23i s 0 0u 0 0 0

" ~ ~ ~= ~ ~ ~ Ca,,' ..".- .cC.r -• E ~ "" ~ "-C v '" Gl.2 :.. 0 ~ ~ " .c· " :: ~ ~ ;;; :g[~ .. ..

~v 0 0 .c0 0 0E !; 0 0 0 '-'!0 " " " 0 00 q q

~ 0.. .. N~ ~ ...

I!!> ..c"-_

0,". III'iii"! E .. .. e- GlCO v ~ ~ ... ::l~~=- iii

>0 <"C_Q) ~

~ N.0 0 ~ ~(; en 1;; 1;; 1;;

..C

•~•

~ •0 0 ~• v

"0~ -.~

v 0 ...° ll!~ Jiw;-•= 1:- -g'i~~ r,~

0 !0 0,- ::::I E~...l..JE:Ci ~ ~c

'C ~

..:. ~:J~~ ~a

EE~V~

'"'"'"c'"u:c!::.Q;J!!Ul

E::lti2~

Ul

'"'C~Cl"E'"'Ce'"iii.sIn

'"InIne~

Ul

'":cj<

STANDARD GRADETO THE EGYPTIAN

28Allowabfe Stresses

The allowable stresses for tension, compression, and bending incast steel of the grade CST 55, shall not exceed the allowablestresses indicated in Table 2.6.

These stresses are to be used for structures subjected to staticloads or moving loads as well as for roadway and railway bridges.

The maximum stresses shall in no case exceed the values (Ucm2)

indicated in Table 2.5.

2.9.1 The allowable stresses for tension. compression. and bendingIn cast steel of the grade CST 44 shall not exceed the allowablestresses prescribed In Clause 2.8 for structural steel St 44.

2.8 ALLOWABLE STRESSES INSTRUCTURAL STEEL CONFORMINGSTANDARD SPECIFICATION

Tile gross moment of inertia and the gross statical moment shallbe used In calculaling the shearing stress In plate girders and rolledbeams.

The gross sectional-area measured normal to the axis of themember shall be considered for all compression members exceptwhere holes are provided for black bolts in which case such holesshall be deducted.

~I;;

~6~

~

'"

"x~

_E

N"':N

MN":o

~

~

.ci

~::IIIIQ>C

'"a::'"'0C

'"~Q>

".5>.o

'"c~

~aICle'c

'"Q>

aI-oQ>..'"o

M

~o

"~

_E

~

"':N

...... I~

~I~

..... l~

NQ>

5

"""I~

...... I~

~I-

+

~N

MN":o

~ "Q> X.. ~

'" Eo -

%:i!Q>'0.5J'~cQ>

~aIClc'c'"Q>

aI

'0Q>..'"o.,;

Q) ~

.c;0~U>

C Q)

~~:0 l!!Q) m~

::10>U> COO"j;;;

l!! mc..2l0>­cO-c; II)

"'t::Q) '".cc.Q)­.c;C-Q). :u~~E'O

..Q~mN-;;~t:::mgQ) Q) 0I~';;;o Q) '"~.c-o

~t3 .$:c!9~~ c ::I00 0ooro0_ o<(0U>

• Q)'-

~~2f~ 't: .£:

• ::I 0NU>C.

c cQ)Q).c;.:<~.lll

~.~0u>NQ)

>oU>.e~'OJ,Q) U>'0 _Q) mQ) C

° 0x",Q)~

Q)'O.em>0'0m CEmU>1:­Q)mU>EXl'c~ c.1;)'0.9!c.eoOO:p:0 mg~m E:20m °ID E .~::I-

.EE§ro._ 0Q) ~ u.c;Eof- m

Q).9-5.S:

,;g c

0.;;;~k- ~ 00 0o E coo mo °Ie rN 0":= E~ .. 0

:: =0

· ..• l!!" ~o III

~I~ .~ 00 00- E'IIi 'C -e co 0 MID, lL c ""';C'\i 00Q>

aI

•,I••,

;'" <D C

! u, '" .. .9I

~ ~.. U>~ U>I .. _cQ)

~'c 0 LL U.Q QQ> W U> E~

1Ji :ij 0..~::!i cf-U

I -0 Ei U>

I~~ 00VI! ro "mI U LL UI

f-

000U> -1:::$0)~ 1i) .f:

-0Q) -0 C.<:Q)Q)~ o>.eC ~

:.::..E 0N -0 ~Ect)° m Q)~--Ec Q) ::I._ S II)

mU>a>1i)'O~rocQ) ° m~~ ..u>C~

~.g ......e~Q)mu>~~mC.oom~oc3Q) Q) C~ "0 "­~m

:cE~.::: ~~0> 0> °(0 ,S: ~C'\iL:(/)

..!!:!"O(J)c

..c C ID QCO ro :;::; '-..... U>ro~

"I""' g'::3 ~d 'C c- 0­_rowEN l1>..c 0.e~o

IIIWezi:c~IIIeZ

~aI

~IIIWIIIIIIWII:

~W..J

~..J

;;!o~

N

r-(~.,

Compression and Buckling Tension and Tension and Shear in

Grade TensionFe(Ucm2) "(1) Compression due Compression Web

Cause of Stress Of Fr: 0.58 Fyto Bp.ndin~ due to Bendin? "(4)

2) '(' q.n=0.35 FySteel (tlern?) KUr c 100 KUr~ 100FD=0.64 Fy Fh,=0.58 Fy

(tfem?)(t/em?) (tlcm2)

1-Primary Stresses

St 37 1.3 1.3-O.000055(Ktlr)2 7500/(Ktlr)2 1.38 1.3 0.75

Dead LoadLive Load SI44 1.5 1.5-0.0OOO75(Ktlr)? 7500/(KUr)2 1.63 1.5 0.89Dynamic EffectCentrJfugal Force

St 62 2.0 2.0-0.000125(KUr)2 7500/(KUr)2 2.14 2.0 1.17

II· Primary and Additional All values are 20% higher than for item IStresses (51

• Table (2.5b) Allowable Stresses in Standard Grade Structural Steel (100 mm ~ Thickness t > 40 mm)

*(1) For axially loaded symmetric sections.

·(2) For compact sections satisfying the requirements of Clause 2.6.5.1.

·(3) For compact sections not satisfying the requirements of Clause 2.6.5.1 or non-compact sections satisfying the requirementsof Clause 2.6.5.5.

·(4) For sections satisfying the buckling requirements of Clause 2.6.3.1.

*(5) Dead Load, live Load, Dynamic Effect, Centrifugal Force, (Wind Pressure or Earthquake Loads), Braking Force, lateralShocks, Temperature Effect, Frictional Resistance of Bearings, Settlement of Supports & Shrinkage and Creep of Concrete.

Allowable Stresses 30

c. Case of Bearing Between Two Spheres:

Case 1(Bearing between lull sphere against full sphere)

Imax

= 0.394 3 E'V ( ~ + ~ )' 2.43r1 r2

II

MaterialAllowable Bearing Siress

(tlcm')

For Cast Iron CI14 5.00

For Rolled Steel SI44 6.50

For Cast Steel CST 55 8.50

For Forged Steel FST 56 9.50

2.10.3 The allowable load V (ton) on a cylindrical expansion rollershall not exceed the following values:

Case 2(Bearing between lull sphere against hollow sphere) Material

~ 2 1 1 2I = 0.394 3 E V ( - - - )mn ~ ~2.44

Rolled steel

Rolled steel

Cast steel

St37

SI44

CST 55

Allowable Reaclion(Ion)

0.040 d.1

0.055 d.1

0.095 d.l

d. Case of Bearing Between a Sphere and a Plane Surface: Forged steel FST 56 0.117 d.1

fE'vfmax = 0.394 3~7

2.45

Where:d =I =

Diameter 01 roller (em).Length of roller (em).

r,r,rEV1

Where:fmax

= Maximum actual bearing pressure at thecontact (t/cm').

= The bigger radius 01cylinder or sphere (cm).= The smaller radius of cylinder or sphere (em).= Radius 01cylinder or sphere (em).= Young's modulus (t/cm').= Maximum load on bearing (ton).= Bearing length (em).

surface of

In the case of movable bearings with more than two rollers, wherethe compressive lorce affecting the said rollers cannot be equallyshared by all their parts, Ihe aloresaid allowable reactions shall beincreased by 20%.

2.10.4 When bearings are provided With cylindrical cast steel knucklepins, the diameter (d) of the pins shall be given by the lormula:

2.46

For fixed, sliding, and movable ~earings with one or two rollers,the allowable bearing stresses (t/cm ) shall be as given below, whenthe surface 01 contact between the different parts 01 a bearing arelines or points and when their design is carried out according to Hertzlormula, assuming these bearings are subjected only to the primarystresses designated in Clause 2.2.1.

Where:d =V =I =

Diameter 01pin (em).Vertical load (ton).Length of pin (cm).

Allowable Stresses32

33

The bearing pressure between pms made of east or forged steela

and the gusset plates shall not exceed 2.40 t/crn .

2.11 AREA OF BEARINGS OR BEDPLATES

The contact area of bearings or bedplates shall be so proportionedthat the pressure due to the primary stresses on the materials form;n~

the bearing base foundation shall not exceed the values (kg/em)indrcated In Table 2.7

Table (2.7) Allowable Bearing Stresses on the Materials Formingthe Bearing Foundations

AllowableType Of Bearing Bearing

Stress (kg/em')

Pressure on lead sneetmq or cementmortar layer between the metalbearing plates and

a. Bearing stones made of granite, 40basalt. or SImilar hard stones

b. Concrete templates reinforced 70 for C 250With circular hoops or heavilyreinforced caps under the 110forC350bearings.

CHAPTER 3

FATIGUE

3.1 SCOPE

3.1.1 General

This Chapter presents a general method for the fatigue assessmentof structures and structural elements that are subjected to repeatedfluctuations of stresses.

Members subjected to stresses resulting from fatigue loads shall bedesigned so that the maximum unit stresses do not exceed the basicallowable unit stress given in Chapter 2. and that the stress range doesnot exceed the allowable fatigue stress range given in this Chapter.

Members SUbjected to stresses resulting from wind forces only, shallbe designed so that the maximum unit stress does not exceed the basicallowable unit stress given in Chapter 2.

Cracks that may form in fluctuating compression regions are self­arresting. Therefore, these compression regions are not subjected tofatigue failure.

3.1.2 Definitions

Fatigue: Damage in a structural member through gradual crackpropagation caused by repeated stress fluctuations.

Design Life: The period in which a structure is required to performsafely with an acceptable probability that it will not fail or require repair.

Stress Range: The algebric difference between two extreme veluesor nominal stresses due 10 fatigue loads. This may be determinedthrough standard elastic analysis.

Fatigue Strength: The stress range determined form test data for agiven number of stress cycles.

34Fatigue 35

,,'44

Fatigue Limit: The maximum stress range for constant amplitudecycles that will not form fatigue cracks.

3.2.2 Factors Affecting Fatigue Strength

The fatigue strength of the structural elements depends upon:

Detail Category: The designation given to a particular joint or weldeddetail to indicate its fatigue strength. The category takes intoconsideration the local stress concentration at the detail, the size andshape of the maximum acceptable discontinuity, the lo~ding condition,metallurgical effects, residual stresses, fatigue crack shapes, thewelding procedure, and any post-welding improvement.

1- The applied stress range.

2- The detaii category of the particular structural component or joint

design.

3- The number of stresscycles.

3.2.1 General

3.2 BASIC PRINCIPLES

1- The differences in fatigue strength between grades of steel are small

and may be neglected.

6- Slotted holes shall not be used in bolted connections for members

subjected to fatigue. 37F.tJgue

3- Railway Bridges: The fatigue loads used to calculate the stress rangeare the full standard design live loads.

3.2.4 Fatigue Assessment Procedure

2- Roadway Bridges: The fatigue loads used to calculate the stressrange are 60% of the standard design live loads including the

corresponding dynamic effect.

For bridges carrying both trucks and trains, the fatigue load is thecombined effect of the full railway live load and 60% of the traffic live

loads.

i- The fatigue assessment procedure should verify that the effect of theapplied stress cycles expected in the design life of the structure is less

than its fatigue strength.

il- The effect of applied stress cycles is characterized by the maximumstress range (F...). The maximum stress range can be computed fromthe applied fatigue loads using an elastic method of analysis. Thefatigue loads should be positioned to give the maximum strainingactions at the studied detail. In some structures such as bridges and

1- Cranes: The fatigue load used to calculate the stress range is the fulltravelling crane load including impact.

3.2,3 Fatigue Loads

36Fatigue

3- Cracks generally occur at welds or at stress concentration due tosudden changes of cross-sections. Very significant improvements infatigue strength can be achieved by reducing the severity of stressconcentrations at such points.

4- When fatigue influences the design of a structure, details should bepreciSely defined by the designer and should not be amended in anyway without the designer's prior approval. Similarly, no attachments orcutouts should be added to any part of the structure without notifying

the designer.

5- Structures, in which the failure of a single element could result in acollapse or catastrophic failure, should receive special attention whenfatigue cracks are a possibility. In such cases, the allowable stressranges shall be limited to 0.8 times the values given in Table 3.2 or in

Figure 3.1.

2- The differences in fatigue damage between stress cycles havingdifferent values of mean stress but the same value of stress range may

be neglected.

cranes, consideration should be given to possible changes in usagesuch as the growth of traffic, changes in the most severe loading, etc.

iii- In non-welded details or stress relieved welded details subjected tostress reversals, the effective stress range to be used in the fatigueassessment shall be determined by adding the tensile portion of thestress range and 60% of the compressive portion of the stress .anqe. Inwelded details subjected to stress reversals, the stress range to beused in the fatigue assessment is the greatest algebraic differencebetween maximum stresses.

iv- The fatigue strength of a structural part is characterized by theallowable stress range (F,,) which is obtained from Table 3.2 or Figure3.1 for the specified number of constant cycles and the particular detaii

category.

v- The number of constant stress cycles to be endured by the structureduring its design life is given in Table 3.1a for roadway bridges, Table3.1b for railway bridges, and Table 3.1c for crane structures. Thenumber of cycies given in Tables 3.1a to 3.1c is subject to modificationsaccording to the competent authority requirements.

vi- In detailing highway bridges for design lives greater than 50 years,the fatigue loads should be increased by a magnification factor, M,given by the following Table:

No. of YearsMa nification Factor, M

vii- Each structural element has a particular detail category as shown ipTable 3.3. The classification is divided into four parts which correspondto the following tour basic groups:

viii- When subjected to tensile fatigue loading, the allowable stressrange for High Strength Bolts friction type shall not exceed the following

values:

Number of CyclesAllowable Stress Range F" (Vern')

Bolts Grade Bolts Grade(N)

(8.8) (10.9)

N s 20,000 2.9 3.6

20.000 < N s 500.000 2.6 3.2

500,000 < N 2.0 2.5

Table 13.1a\ Number of Loading Cycles - Roadway BridoesNumber of Constant Stress

. Cycles (N)Type of Road ADTT

Longnudinal Transverse

Members Members

Major Highways Over

and Heavily;, 2500 2.000.000

2.000,000

Travelled Main

Roads< 2500 500.000 2.000,000

Local Roads 100.000 500,000

and Streets

• ADTT = Average Daily Truck Traffic for 50 years design life

Group 1: non-weided details, plain materials, and bolted plates.Group 2: welded structurai elements, with or without attachments.Group 3: fasteners (welds and belts).Group 4: orthotropic deck bridge details.

Fafigu8 38Fatigue 39

'··nti>""4

and Figure 3.1 are based on the follOWing q

Log N =log a-m log F..

= The number of constant stress cycles= The allowable stress range .= constants that depend on the detaIl category as

follows: LogaDetail Category m

3 6.901A

3 6.601B

3 6.329B'

3 6.181 .

C3 5.B51

03 5.551

E3 5.131

E'5 4.286

F

Where:NF..m and log a

Table 3.2

) f Number of ConslantTable (3 2) Allowable StresS Range (F.. or

Stress Cycles (N)F" (tlcm )

~Over

100,000 500,000 2,000,000 2,000,000Detail

Category1.68 1.68

A 4.30 2.52

2.00 1.26 1.12B 3.42

1.02 0.652.77 1.62

B' 0.701.45 0.91

C 2.480.49

1.92 1.12 0.710 0.32

1.53 0.89 0.56E 0.1B

1.11 0.65 0.41E' 0.36

0.52 0.40F 0.72

E uation:

ADA::;; Average Daily Application for 50 years design life

iable (3 lc) Number of Loading Cycles - Crane Structures

Table (3 lb) Number of Loading Cycles - Railway Bridges

. Number of ConstantADA Field of Application

StressCvcles IN)5 Occasional use 100,000

Regular use with intermittent25 500,000

operation

Regular use with continuous100 2,000,000

operation

".> iOO Severe continuous operation According to actual use

.

Member Description Span Length IL) Number of Constant1m) Stress cvctes IN)

Class I L > 30 500,000Longitudinal flexural

30>L>10 2,000,000members and theirconnections, or truss L c 10 Over 2,000,000chord members includingend posts and theirconnections.Class IITruss web members and Two tracks loaded 200,000their connections exceptas listed in class 111

One track loaded 500,000

Class IIITransverse floor beams Two tracks loaded 500,000and their connections ortruss verticals and sub-diagonals which carry floorbeam reactions only and One track loaded over 2,000,000their connections

Fatigue 4041

Fatigue

o

Allowable Stress Range Fsr (tlcm2)

Table (3.3) Classification of DetailsGroup 1 : Non-Welded Details

43Fatigue

DescriptionIllustration Class

1.1. Base metal with rolled orcleaned suriaces; flame cut ~~

A

edges w1~~ surface roughnessless tha" ~,un ~~ I---1.2. Base metal with sheared orflame cut edges with a surface

B

roughness less than 50 /.LID

2.1. Base metal at gross sectionof high strength bolted slipresistant (friction) connections, B

except axially loaded joints -C£::j-which induce out of planebendin~ in connected material. - \-----

2.2. Base metal at net section offully tensioned high strength

B

bolted bearing type connections "=I 2.3. Base metal at net section of -C2LJ

other mechanically fastened - D

I joints (ordinary bolts & rivets).

3. Base metal at net section ofeye-bar head or pin plate. net sedlOfl arn

@=3-E

net sedlOfl areft

\

u-:;o"0

"·0oo

"0

0

00 II I II JrJ 0,

17, 7 J,,

I I I

::;0

"00

, il'!l0'I

/J1/ r/1'

I 'I/JI/JII I

,

,

IJIi JIll! / I !

! J I~~

I

> ,

-:'111

f-. ,

II i I,

'" !

i

I i

'" , , !,

zogo

go

."~c;..:..

!!!;....;0..".,m

.... ~ro ~

c•Zc3e-~

2.00

"..;-a~•..0'<i"..

Illustration ClassDescription

9.1. Base metal and .....1d metal atfull penetration grooveweldedsplices (weld ITlIiIde from both

-c Bsides) of parts of similar cross i ---=n_sections ground flush, withgrinding in the directionof appliedstress and weld soundnessestablished by radiographic orultrasonic inspection.

f---9.2. Same as (9.1.) butwilh

(~JC

reinforcement not removed ande---less than 0.10 of weld width.

9.3. Same as (9.2.) withDreinforcement marethan 0.10 of

weld width.

10.1. Base metal and weld metalat full penetrationgroove weldedsplices (weld made~m. bothsides) at transitions InWIdthorthickness, with welds ground to

B'provide slopes no sleeper than 1to 2.5 with grinding in the

~--..direction of applied stress, andwith weld soundnessestablishedby radiographic or ultrasonicI in.poelion,

--"CZJ--.. e.--10.2. Same as (10.1.) but with

CI reinforcement not removed andless than 0.10 oflNeld width.

f----1 10.3. Same as (10.2.) \Mthslopes

DImore than 1 to 2,5

e.--10.4. Same as (10.1.) to (10.3.)but with welds madefrom one

E'side only.

c

8'

D

D

c

'Class II Illustration

4.2. Same as (4.1.) with weldshaving stop - start positions.

4.3. Base metal in members! without attachments, built-up

plates or shapes connected bycontinuous futl penetration groovewelds with backing bars notremoved, or by partial penetrationgroove welds pareUel to thedirection of applied stress.

Description4.1. Base metal in memberswithout attachments, built upplates or shapes connected bycontinuous full penetration groovewelds or by continuous fillet weldscarried out from both sides withoutstart stop positions parallel to thedirection of applied stress.

Group 2 : Welded Structural Elements

I6. Base metal at zones ofI intermittent longitudinal welds withi gap ratio glh < 2.5

ase meta at ccntmucusmanua/longitudinal fillet orfuUpenetration groove welds carried

I out from one side only. A good fit

I

, between flange and web plates isessential and a weld preparationat the web edge such that the rootface is adequate for the

; achievement of regular rootI penetration.

I 7. Base metal at zones containing

II copes in longitudinally welded T­, joints.

I 8. Base metal at toe of welds on: girder webs or flanges adjacent to

welded transverse stiffeners.

Fatigue" 44 Fatigue 45

Description Illustration Class

E16. Base metal at plug or slot -e:tt=J=welds.

17. Base metal and attachmentat fiDeI. welds or partial Groove or fjJIel weld

penetration groove welds with

~-main material subjected tolongituclinalloading and weldtermination ground smooth •

~R"50mm.

ERo:::50mm

18. Base metal at stud· type

~shear connector attached by Cfillet weld or automatic end \'\l8ld.

19.1. Base metalat detailsattached by full penetrationgroove 'N'8lds subject tolongitudinal loading with weldtermination ground smooth.weld soundness established byradiographic or ultrasonic

GrllO"le weld

inspection

~--B

R"610mm r--c610mm" R > 150 mm ,

~150mm>R,,50mm f---

R<50mmE

c--19.2. Same as (19.1.) withtransverse loading, equalthickness. and reinforcement

removed. BR>610mm -c610mm"R>150mm

150mm>R>50mm-0

R<50mm~

E

---,~~:::::::

t: thickness

members with fillet weldedconnections.t s 25 mm,

--'~:;;, e----!

t s zs mrn E'

i 14. Base metal at members

I, connected with transverse fillet iet:Jwelds.

,CI I p---

I15.1. Base metal at full

i penetration weld in cruciformi joints made of a special quality

~0

! weld.

I 15.2. Same as (15.1) with partial-

i penetration or fillet welds of E', normal quality.

!Description Illustration Class

11.1. Base metal and weld metalat transverse full penetrationgroove welded splices on a i 0backing bat. The end of the filletweld of the backing strip is more ~

i

than 10 mm from the edges ofthe stressed plate

11.2. Same as (11.1) with the-

fillet we!d less than 10 mm fromthe edges ofthe stressed plate. E

12.1. Base metal at ends ofpartial length welded cover plates

Plate",narrower than the flange havingsquare or tapered ends, with or fI£n~ge:t~Z~wnwithout welds across the ends or BEarE'wider than the flange with welds

(~:O~at the ends.Flange thickness ~ 20 mm EFlange ttuckness > 20 mm

f--;-

12.2 Base metal at ends of e-E-

Ipartial length welded cover plates E'wider than the flange without endwelds.

I 13. Base metal at axially loadedi t:: thickness

I

Fatigue 46 Fatigue 47

Group 3 : Fasteners (Welds and Bolts)

(W Id and bolh)Group 3: Fasteners , s

Description Illustration Class

22.1. Weld metal of full(3)E 3_penetration groove welds

parallel to the direction of

(~B

applied stress ( weld from bothsides\ {b) 014-.: .) -22.2. Same as (22.1.) but with

Cweld from one side only

22.3, Weld- metal of partial -c I _:J_penetration transverse grooveFweld based on the etrecuve

~.)throat area of the weld. (

23.1 Weld metal of.continuous

~ amanual or automatic longItudinalfillet welds transmitting acontinuous shear flow.

23.2 Weld metal of intermittent

~ Elongitudinal fillet weldstransmitting a continuous shearnow.

23.3 Weld metal et fillet welded-~-=:::lab joints.

-~~E

I24, Transversally loaded fillet Ewelds

F25. Shear on plug or slot welds.

26. Shear stress on nominal

~ Farea of stud·type shearconnectcre.tpallure in the weldor heat affected zone.)

27.1. Hight strength bolts inCsingle or double shear (fitted bolt

----0-of bearing type).

i 27.2. Rivets and ordinary boltsI in shear.

F1 28. Bolts and threaded rods intension (on net area)

Description Illustration Class

19.3. Same as (19.2.) but ,reinforcement not removedR>610mm

Cf---I 610mm>R>50mm

~f 150mm>R>50mm

~R>50mmr---E-19.4. Same as (19.2.) but with

unequal thickness

I R>50mm 0f---R<50mm I

i.s..I19.5. Same as (19.4.) but withreinforcement not removed and Efor all R

20. Base metal at detailiattached by full penetration

I 0 !

groove welds subject to!longitudinal loading

~)So-mm< a <12t or 100 mm

~a >121 or 100 mm (1<25 mm) ~' ---.a >121 or 100 mm (1)25 mm)

21. Base metal at detail ; Iattached by fillet welds or partial

~penetration groove welds

a f---sUbject to longitudinal loadinga<50mm ~

C,

50 mm< a <121or 100 mm

h r0-C--

Ia >12t or 100 mm (1<15 mm) Z \ 1- E

Ia .,

E'a >121or 100 mm «(>25 mm)

Fatigue 48Fatigue 49

..

CHAPTER 4

Group 4 . Orthotropic Deck Bridges

Description I Illustration ClasSTABILITY AND SLENDERNESS RATIOS

4.1 GENERAL

32.2. Same as (32.1.) with weldreinforcement '5: 0.2

34.2. Weld metal at fillet weldconnecting deck plate to ribsection.

·1 34.1. Weld metal at full, penetration weld connectingI deck plate to rib section.

4.1

Table(4.1) Maximum Slenderness Ratio for CompressionMembers

where;A = The slenderness ratio,K = The buckling length factor:

For a compression member, K depends on therotational restraint at the member ends and the meansavailable to resist lateral movements.For tension members, K = 1.0

L = The unsupported length for tension or compressionmembers.

= The radius of gyration corresponding to the member'seffective buckling length (KL).

4.2.1 The slenderness ratio of a compression member, shall notexceed Am.. of Table 4.1

4.2 MAXIMUM SLENDERNESS RATIOS Am..

Member Amax

Buildinos:Compression members I 180Bracina systems and secondarv members I 200Bridqes:Compression members in railway bridaes 90Compression members in roadway bridaes 110Bracina svstems 140

4.1.2 The slenderness ratio of a member shall be taken as:- K·LA.=-

r

4.1.1 General stability shall be checked for the structure as a wholeand for each individual member.

E'

o

c

>--­o

M ~'

\ \ / /,

1

~"C

\ / __II<8~ "I

\

E'

"

LJ~ 0lJi

tJO

I if)iT

lJt E' \

s: 1 r::cJ~

\J

32.1 . Base metal at rib joints \made of full penetration weld \withOut backing plate. All weldsground nushto plate surface in I

the direction of stress. Slope ofthicknesstransition < 1:4.(Bendingstress range in the rib)

33. Base metal at connection ofcontinuous longitudinal rib tocross girder. (Equivalent stressrange in the cross girder web).

I31. Base metal at rib joints \made of full penetration weld

Iwith backlng plate.( Bending I,

stress range in the rib)

Fatigue 50S/abiJity andSlenderness Ratios 51

~" q

4.3 BUCKLING FACTOR (K)

4"' p

'~J.;V ""'''I''

BUCKLINGMOOE

/"'~ '" "'~ '" i'" ,,;

k 0.65 0.80 1.20 1.00 2.10 2.00

ENO i ROT~TION PR[v[NTED.TR~NSLATION PREVENTEDCONOITIONS

Y ROT~TION PERWmED.TR~NSLATION PREVENTED

"i RDT~TION PREVENTEO,TR~NSLATION PERMITTED

i RDT~TION PERWITTED.T~NSLATIDN PERMITTED

Table (4.3) Buckling Length Factor for Members with WellDefined End Conditions

The use of rods and cables in bracing systems or as a maintension member is prohibited in this code.

4.3.1 The recommended values for the buckling iength factor( K _ Equation 4.1 ) are given in Table 4.3 for members with well­defined ( ideaiized ) end conditions.

.Table (4 2) Maximum Slenderness Ratio for Tension Members

4.2.2 The slendemess ratio of a tension member shall not exceed

Am",ofTabte 4.2

Member 1 I..max

Buildinns:Tension members 300

Bridnes:Tension members in raiiwav bridnes 160

Tension members in roadwavbridoes 180

Verticai hanoers 300

Bracino svstems 200

4.3.2 Trusses End U-Frcme

4.3.2.1 The effective buckling length (KL) of a compression memberin a truss is either obtained from Tabies 4.4 and 4.5 for buildings andbridges respectively, or determined from an elastic critical bucklinganaiysis of the truss.

4.3.2.2 For a simply supported truss. with lateraiiy unsupportedcompression chords and with no cross-frames but with each end ofthe truss adequateiy restrained ( Figure 4.1 ). the effective bucklinglength (KL), shaii be taken equai to 0.75 of the truss span.

I<L=O.75L

KL=O.75L

Figure (4.1) Truss with a Compression Member LaterallyUnbraced

Stability and Slenderness Ratios S2 Stabmty and Slenderness Ratios 53

In case of symmetrical U-frame with constant moment of inertiafor each of the cross girder and the verticais through their ownlength, 0 may be taken from:

The U-frame is considered to be free and unconnected at allpoints except at each point of intersection between cross girder andvertical of the truss where this joint is considered to be rigidlyconnected.

4.3.2.3 For a bridge truss where the compression chord is laterallyrestrained by U-frames composed of the cross girders and verticalsof the trusses, the effective buckling length of the compression

chord (4) is

UilRrce

~IBI..

The distance from the centroid of the compressionchord to the centroidal axis of the cross girder of the U­frame.The second moment of area of the vertical memberforming the arm of the U-frame about the axis ofbending.

= The second moment of area of the cross girderabout the axis of bending .The distance between centres of consecutive maingirders connected by the U-frame.

yo , 0

~ r- ) ~~~I~

, / \ ,

I / ~ I11d:2 11,

1\ 12 /

" =-- - ._----:;

'- -----y -----

Rrce

Figure (4.2) Lateral Restraint of Truss Chords by U-Frame

B

4.3. . ...... ..... . ......•................

The distance from the centroid of the compressionchord to the nearest face of the cross girder of the U­frame.

e. = 2.5· ~E . " . a . 0 ~ a...... ...... 4.2

The Young's modulus (tlcm').The moment of inertia of the chord member about theY_Y axis shown in Figure 4.2 (ern").

= The distance between the U-frames (ern).The flexibility of the U-frame: the iateral defiection nearthe mid-span at the level of the considered chord'scentroid due to a unit load acting laterally at each chordconnected to tne U-frame. The unit load is applied oniyat the point at which c is being calculated. The directionof each unit load shall produce a maximum value for 0(cm).

Where:d,

aC

Where,EI,

Stability and Slendemess Ratios 54Stability andSlenderness Ratios 55

J[

rE~g.~

g:

Table (4.4) Buckling Length of Compression Members in Buildings and in

Bridge Bracing Systems

Out of Plane

Member In-Plane Compression Chord Compression ChordEffectively Braced Unbraced

f-----------

~

• e e 0.75 span

(Clause 4.3.2.2)

D1ggoog!s

-Single

~ e e 1.2eTriangulatedweb system

-MultipieIntersectedweb reetangula

~ 0.5 e 0.75 e esystemadequatelyconnected

~.'.""

'~

Out of Plane

totembe" In-Plane Cornp,..sslon ChOf'"d compression ChordEffectlve'v BrQced Unbraced

0199009's

-Multiple

~ e 0.8 edIntersected---

web trop.zoldalsystemadequately ,connected

- K-system ~ e 1.2 e 1.5 e

v-rtlsq'm.mb·D

~e e 1.2 e-Single

triangulatedweb system

-K-fntersected(0.75+0,25~')t (0.90+0.30 ~') tweb system

~t0.5 e , ,

~

~i Tobie (4.4) Buckling Length of Compression Members in Buildings and in

i Bridge Bracing Systems (Cont.)

fI

Ns = Smeller value of compression forceN

L= Larger value of compression force

Out-al-Plone

In-PlaneI--~ ----~

Member Compression Chord Compression ChordEffectively Braced Unbraced

-_.~----~-- -- --- -~._--~

~ ~0.75 Span

0.85 e(Clause 4.3.2.2)

~0.85 e or Equation 4.2 if

using U-Frames

-~-----~---f------~

-~-

Piggonals

-Single

~ 0.70 e 0.85 e 1.2eTriangulated

web system

l-- --f-~-------~

-MultipleIntersectedweb reetangula

~0.85 e/2 0.75 e e

systemadequatelyconnecled

'"ex>

~~ Table (4.5) Buckling Length of Compression Members in Bridges

~0-

r~i."

~~~~

Out-al-Plone

Member In-Planel-- -Compression Chord Compression Chord

-----Effeclively Braced Unbroced

------- -----~--~--~

- K-system

~0.9 e 1.2 t 1.5 e

-- f--~.---~--- ~

Verticglmembers

-Single

~0.7 e 0.85 e 1.2 e

triangulatedweb system

_K_interseeted . NS)f (O.90+0~30~s )fweb system~e

0.35 t \O.75+0.25 Nt, t.

:8

Ns= Smaller value 01 compression lorce

NL= Larger value of compression force

!!lJ Table (4.5) Buckling Length of Compression Members in Bridges (Can!.)

~

!l}

I~~

"

4.3.3 Columns in Rigid Frames

Table (4.6) G values for Columns with Special End Conditions

4.3.3.1 The buckling factor (K) for a column or a beam-column in arigid frame is obtained from the alignment charts given in Figure 4.3.

CIC

~U::llJl :l'-E.2!

11-

~:2OICI

tP~c-'-c .,., c

E EC ::lCI-

~8

e::lCI;;:

~~~~ :d = = ::l :! =co: 0: 0: .. .,8 0 0 0 0

0,"" M '"

I I I'" 11111 I I II II I II I I I I I I I I I't:J.,<!>

""E= :!

.,== =0 0 "' Q.do o.r;i .... M " >-N_

I I 01'" 8111[111 II ! I I I 1 1 1 II 1 I I I 1 I I :l:Ul

".:2In

<I I I I I I I III III I I II II I II I I I I<!>

=!C!'=!O:O: 0: '" 0 ::l '" =8Qe <;I 0

M -od d 0 ~=;r-.~ on ~

~..., M o;v

= ~cici :; ~ ci ~ N N ci 08:;:; ~~ " 0 0 0"'- II I I II I I I I I I I I ]l'" 1111111111 II I 1

<!> c:~l'!

'"Q.= e- = >-0 = 0 00 0 0 co-

I I ~'",

1I , I I I I I

1 i , .,:2In

< I I I I I I Io 1111111111 II I I I I I I I II I:!dd~ ~~ ~

.., N - =80:0: ~O:0

0 0~=: .,."..M " = 0

A

B

G. = 1.0

r777T7T

G, = 10.0G.

A

ColumnBase

Condition

4.3.3.2 The alignment charts are function of the ratio of the momentof inertia to length of members (IlL). Conservative assumption ismade that all columns in the portion of the frame underconsideration reach their individual buckling loads simultaneously.The charts are based on a slope deflection analysis. In Figure 4.3,the two SUbscripts A and B refer to the points at the two ends of thecolumn or beam-column under consideration, while G is defined by:

L (I I L) columnsG L(I1L)girders 4.4

Where, the ~ indicates a summation of (IlL) for all membersrigidly connected to that joint (A or B) and laying in the plane inwhich buckling of the column is being considered. L is theunsupported length and I is the moment of inertia perpendicular tothe plane of buckiing of the coiumns and the beams.

4.3.3.3 For a column base connected to a fooling or foundation by a.ricttoniess hinge, G is theoretically infinite, but shall be taken as 10n design practice. If the column base is rigidly attached to a properly"esigned footing, G theoretically approaches 0.0, but shall be taken:JS 1.0 in design practice (Table 4.6 ).

Stability and Slenderness Ratios 60

4.3.3.4 For beams with the far end hinged. the beam stiffness (Ul)gis multiplied by a factor equals 1.5 for sidesway prevented and 0.5

for side sway pennitted. For beams with the far end fixed the beamstiffness (Ul) g is multiplied by a factor of 2.0 for sidesway preventedand 0.67 for sldesway pennitted (Table 4.7 ).

Table (4.7) Beams With Special End Conditions

t""Beam End /"- r;Condition :;:,.,"'""'""$

Sidesway (IIL)g X 1.5 (IIL)g X 2.0prevented

Sidesway (IIL)g X 0.5 (lIL)g X 0.67permitted

The axial compressive strength of the it" rigidlyconnected column.The axial compressive strength of all columns in astorey.

4.3.4 Buckling Length of Compression Flange of Beams

4.3.4.1 Simply Supported Beams

The effective buckling length of compression flange of simplysupported beams-shall be considered as follows :

4.3.4.1.1 Compression Flange With No Intennediate LateralSupport

The following Table 4.8 defines the effective buckling length ofcompression flange of simply supported beams haVing nointennediate supports

Table (4.8) Buckling Length of Compression Flange of SimplySupported Beams Having no Intennediate Lateral

4.3.3.5 To account for the fact that a strang column (or column withlow axial farce) will brace a weak column (or column with high axialforce) a modification for the K factor shall be considered as follows:

Pci = AjFcWhere:

K', and K, ~ The modified value and the value determined framthe alignment charts for the buckling length factorrespectively.

A, and I, The crass sectional area and moment of inertiarespectively of the considered column.

F, The allowable axial compressive stress.Stability and Slenderness Ratios 62

Supports

Compression Flange EndBuckling

Beam Type LengthRestraint Conditions IKe)

End of compression flange ti. 2l.tunrestrained against lateral IE t .1

bendinoEnd of compression flange ti. 2l.

0.85tpartially restrained against lateral IE e'Ibendino

End of compression flange fully ti. 2l.restrained against lateral bending Ie t

'I0.70 t

2: Pc _I_i_Pci

" ~ K·Va I

4.5

stabilityand Slenderness Ratios 63

4.3.4.1.2 Compression Flange with Intermediate Lateral Support

Table 4.9 defines the effective buckling length of compressionfiange of simply supported beams haVing intenmediate supports.

Table (4.9) Buckling Length of Compression Flange of SimplySupported Beams Having Intermediate LateralSupports

Compression FlangeBuckling LengthEnd Restraint Beam Type

Conditions (Ke)

Beams where there is no The effectivebracing to support the buckling length iscompression flange f5. lJ. according to clauselaterally, but where cross

Ie l ;1 4.3.2.3beams and stiffenersforming U-frames providelateral restraintBeams where there is an Distance betweeneffective lateral bracing to f5. lJ. centers ofthe compression flange Ie l

) intersection of thebracing with thecompression chord

Beams where the Distance betweencompression flange is f5. lJ. centers of crossunbraced but supported Ie l ":j girdersbv riGid cross oirdersBeams where the compr-ession flange is supported f5. lJ.by continuous reinforced Ie l )1concrete or steel deck,where the frictional orconnection of the deck to K=Othe flange is capable toresist a lateral force of 2%of the flange force at thepoint of the maximumbendino moment

.~,

4.3.4.2 Cantilever Beams with Intenmediate Lateral Supports

The effective buckling length of compression flange ofcantilever beams with intermediate lateral supports shall be similarto that of simply supported beams having lateral supports as givenin Clause 4.3.4.1.2.

4.3.4.3 Cantilever Beams Without Intermediate Lateral Supports

The effective buckling length of compression flange ofcantilever beams without intenmediate lateral supports shall beaccording to Table 4.10. The loading condition (nonmal ordestabilizing) is defined by the point of application of the load.Destabilizing load conditions exist when a load is applied to the topflange of a beam or cantilever and both the load and the flange arefree to deflect laterally (and possibly rotationally also) relative to thecentroid of the beam. The type of restraint provided to thecantilever tip is detailed in Figure 4.7

Figure (4.4) Continuous Cantilever with Lateral Restraint Only

StabiMy andSlenderness Ratios 64Stability andSlenaemess Ratios 65

~I!

Figure ( 4.6) Cantilever Built-in Laterally and Torsionally

LateralandTorsionalRestraint

/

Torsional

Rest raint

~TopPranceRes t r aint

Figure (4.5) Continuous Cantilever with Lateral and TorsionalRestraint

Table (4.10) Effective Buckling Length of Compression Flangeof Cantilever Beams Without Intermediate Supports

Restraint Conditions Loadina Conditions

At support At tip Normal Destabilizing iFree 3.0 ! 7.5 !

ContinuousLaterally restrainedon top fiance onlv 2.71 7.5 !

with lateral Torsionally 2.4 ! 4.5 !restraint only restrained ontv(see Fig. 4.4) Laterally and

torsionally 2.11 3.6 erestrainedFree 1.0 ! 2.5 !

ContinuousLaterally restrainedon too flange onlv 0.9 e 2.5 !

with lateral Torsionally 0.8 1.5 eand torsionalrestraint (see

restrained onlv ,Laterally and

Fig. 4.5) torsionally 0.71 1.2 erestrainedFree 0.8 ! 1.4 !

Lateral restraint ontop flange only 0.71 1.4 t

Buill- inlaterally and

Torsionallytorsionally 0.6 ! 0.6 t I(see Fig. 4.6) restrained ontv

Laterally and

\torsionally 0.5 ! 0.5 trestrained

Figure ( 4.7) Type of Restraint Provided to the Cantilever Tip

Stability andSlendemess Ratios 67

stability andSlenderness Ratios 66

"~<'"'l-,~>

,

CHAPTERS

(l)<0

oOl..;

o~

..;

o..,...;

o..,.<'i

o..,.N

....M

iii

o<0<'i,

E EE E00~'"I\W

E EE E00on'"~'"1\ VI

VI

EEs­vEEo..,.

EEo..,.VI-

(~o) aJnleJadwa!lSB11\:I1

-

III.,Q...s:III

0;1----'-------+--+--+----1$III

'0~:c..'tl

~"'J----,---,,--r---+-t----t---1c:t;

~ ~III ~ •~ ~ u,

:e Ci5:59:! ~ g'- ""e >= ~Q. _ U)

~ 0"_

0 lfi 1U" E

~ ~ 5., - '"E 'E£;jl!!'3 0.,. z~-!2.1---'--.l---'----j--+-+-1.,:a~68Strucfural welding

5.2 STRUCTURAL WELDING PROCESS, WELDING POSITIONSAND ELECTRODES REQUIREMENTS

iii- For arc welding the weld metal is deposited by the electro-magneticfield. the welder is not limited to the flat or horizontal position,

The different welding positions are shown in Fig. 5.1 where:

5.2.1 Welding Positions

i- In the flat position weld metal can be deposited faster becausegravity is working with the welder, so large electrodes and high currentscan be used.

ii- In the vertical and overhead positions, electrodes diameters below4 mm (or at most 5 mm) are to be utilized otherwise weld metal runsdown,

• Weldability • is the capacity of a metal to be welded under thefabrication conditions imposed, into a specific, suitably designedstructure, and to perform satisfactorily in the intended service,

STRUCTURAL WELDING

The following Clauses regarding the welded connections areapplicable to structures loaded with predominantly static loads, while forfatigue loadings refer to Chapter 3.

Weldability is enhanced by low carbon, fine grain size and restricted(low) thickness. Conversely, it is reduced by high carbon, coarse grain,and heavy thickness. Tabie 5,1 abstracts the requirements coveringweidabiiity related variables,

5.1 WELDABILITY AND STEEL PROPERTIES

otructural welding

iv- The designer should avoid whenever possible the overhead positionsince It IS the most difficult one. '

v- Welds in the shop are usually in the nat position, where manipulatingdevices can be used to rotate the work in a nat position.

vi: Field welds that may require any welding position depending on thearrentation of the connection have to meet welding inspectionrequirements of Clause 5.9.

~!./ . tW r==v--=1",C(' Flat Position

LA=Jt

Over Head Position

Horizontal-Vertical Position

Figure (5.1) Welding Positions

5.2,2 Electrode Requirements

i- The common size of electrodes for hand welding are 4 and 5 mmdiameter. For the nat welding position 6 mm can be used.

Ii - 8 mm fillet weld size is the maximum size that can be made in onerun with 5 mm coated electrodes.

iii- For large sizes several runs of electrode in arc welding are to bemade, while for gas processesany size can be made in one run.

The appropriate electrode type regarding the weld process as well astheir yield and maximum tensile strength are given in Table 5.2.

The different welding processes and the important requirements foreach is as outlined in Clause 5.2.3.

5.2.3 Welding Processes

Weldable structural steels meeting the requirements of Table 5.1are welded by one of the following welding processes:

Shielded Metal Arc Welding (S.M.A.W.)Submerged Arc Welding (SAW.)Gas Metal Arc Welding (G.M.AW.)Flux Cored Arc Welding (F.C.AW.)

The electrode properties matching the welding process as well asthe appropiate welding position is as given in Table 5.2.

5.3 THERMAL CUTTING

Two cutting systems are available:i- Oxyfuel gas, which can cut almost any plate thickness used

commercially.ii- Plasma arc which will cut almost up to about 40 mm thickness is

much faster than Oxyfuel.

I" IIi~i "t

Structural welding70 Structural welding

71

E

£~.s ~ -g~~-g____ I:: Q) ttI- ttl:!: .oCe'-·- 01 0-jJ) f/)~.- .c. ~c ai 0 '0Q).Eai ~ g'c 'Eg- 0cnE~ f/)J ---0 Uctl a ca .9 Q)"C (I,) :t::~:::- ~ .c~ 5~ ~'c:.Q.)Q) as :::J -.c '0 .c f/) 'tn ta di- .coII)\- f/) :::JI- cO _

Q)~o 8 Eg{ =Ca> e~-- ~ e»E W:; 'tn~$Q) (/) .=~:l:1O 0c'-·- ai -'- -

OJ(1)co c: wcu 08,. (ij

-SEen ~ ss mE Q)'!:2a>c - '-II) coG) E,,-,,0 I- Q.c. 0.-'>:;:::cu.o. '0~-ctl Ol U)- Q)-.... Q)"C '- -c0Q)~.c ?!Q)Q)c: a:I - .c. -- ;;.=::1i'iQ) - Q)~- °0 viVJctl"CE 0 ~cuc: C:-c'OQ)

"E e l/'J,-,cu ctl'O:::J"iiieg>-c (ij :::Im- .r::.WOI:>O._-0 _ O.c. C -C(l,)~_

o~g Q) ~t--'(ij Q)iij.c'OU)8Q)'- E S...;E 5.'§.!:'l~;S_ 5 OJ :2 S ttl" .9 E ttl ~. 0) :­

o "E E 0>0c£,. 'cm'O) ctlco_sr s .. "in~:C~.§ Q) Q.1i) Q)

cu§6 E ,-O-a:lQ)·-.D')( ..... ulz'-.-=a ::J5r3 .=0::1 Q)CCIo E t - E OJ'I::: E U) e g..9 C Q)::'-,-.9 ·cCQ):::l~o.'-VlQ):E:u).- .E..!Q Q) ••- ~ E E 01 VI .- .c 1= 0-a::,'--o.ccE_ '-l/'IC'O -t:EO c ..... 0 (/) E c: .- .- - Q) C Q)

:::JQ) '-" '-E-'OQ)'-,,-<1II- tn 16 C;>. '__ ,>:::1 e-en' ::ICI.o.cOlIf) _Q):>1U'c.-O_ c: ttl 0 Q) -'m Q) Q) E ~ \- I- ~ Q) Q)c~o~'OmQ)jJ)fI)\-Q)o~1/)1/)1/)

>.9'~::> '0::> ~ g""6 LL E:s2:J:J-.;t mVl o Q) 1c:.cIQ,)Q) •.~vi E:.oo ..!..5:~:=:::J~·~_~:»

~

f1£

-- - ---- ------- -

Electrode Strength *Process Min, Yield Min, Tensile Chemical Composition Weld Position Remarks

~tre~J) ~:ren?\ht/crn 2 t/cm

Storage ofShield Metal Electrode: Low Carbon All weld

electrodes inArc \J\.'ELDING 3.45 - 6,75 4.25 -7.6 ~oatjng: Aluminium, Silicon, other

positionsdrying ovens

:S.M.A.W) deoxidizers near the pointsis a must.

Electrode: Medium Mn (1.0%) -Fluxes must beSubmerged Nominal Carbon (0.12%) Flat or kept in storage.~rcWELDING 3.45 - 6.7S 4_25 - 8.95 Flux: Finely powdered constituents horizontal weld - usually used inSAW) glued together with silitales. position shop.

gtect.r9..9.&.: Uncoated mild steel, C02 is the leastSas Metal

dioxidized carbon manganese steelFlat or shielding used

~rcWELDING 4.15 - 8.75 4.95 -7.6Shielding Gas: 75% Argon + 25%

horizontal weld in buildings andGM.A.W)

Co., or 10% CO, position bridges.

I--Useful for field

"lux Cored f~~troQ~: LoWCarbon (0.05% welding in~rc WELDING 3.45 - 6.75 1?5 - 8.6 Max.) 1\11 weld

severe coldFCAW)

Flux: Filled inside the electrode positionsweather

core (Self Shielded)conditions.

~ Table (5.2) Electrodes Used for Welding~ ._---- ---- --- - - -- -

~

~~

" The minimum stress depends on type of electrode

Structural welding72

5.5 DESIGN, STRENGTH AND LIMITATIONS OF BUTT (GROOVE)WELDED CONNECTIONS

5.5.1 Nomenclature Of The Common Tenms

Fig. 5.2 shows the nomenclature of the common terms for groovewelds.

5.5.2 Different Types Of Groove (Butt) Welds

Table 5.3 shows the different types of groove (butt) welds classifiedaccording to their particular shape and named according to their specificedge penetration requirement.

Table (5.3) Types of Groove Butt Welding

Stmcrural welding

Figure (5.21 Butt (Groove) Weld Nomenclature

Partial penetration(When reinforcing fdlet

is specifiad)

1. Iu " II ' ,1

2. I"" , i« &:ESi Ssquare- Butt

• VVelded rtom one side: SquareBun wil.h Backing Barup to 1.5 mm thick-no gap.

• Yt/eIded from both sides • Normal Electrodes ;using Normal Electrodes ; up to 5 mm. thick. 5mm gap.up 10 3 mm. Ihick-no gap. upto 13mm.lhick. 8mmgap.up 10 5 mm. thiclc-take1.5 mm gap. • Deep PenetrationElectrodes:

• IJVelded from both sides using up10 13irim. thiCk. 6mrn gap.deep penetration electrodes:up to 16 mm. -no gap.

I 3. ~~ 4. rP~,@'\\WlSingle "V' Butt Weld

Included Angle: Single V ButtYlfekl6d'rorflatposition. 'tWh BackingBar7riror verticalposition.

• Included angles as(3).ad'ror over head position.

Root Thickness: • Gap3mm.-5rrm.

().3 mm. • Thickness up to 25 mm .Thickness up to 25 mm .

Gap1.5mm-3mm.

5.~~ 6.~~Slngle·U" ButtVWId

Double 'V' Butt weld • Inculded angle 206• 40'

Induded angle gap oGap3mm._Smm.and root thickness as(3)

• Root thickness3rnm.-5mm.

• Thickness 13 mm. - 50 mm.• Root radius 3rmlAOrrm.

• Thickness 25nvn.-5Omm.

~,SP,oe' b~'

IRoot ,:openning

WeldsiZe Effective throat "

lytS,'0 I Root

faceRootopennmg------

Partial penteration

t

Groove (and" bevel) angle

<.~.

J:~ye'rj.diusI •

K:: l-i Root face

Rootooennmo

Preparation

Reinforcement

Groove size

1':"'-""',' Groove angle

aootjgceI! /: /"'-'''-,!,/ Fillet size-·...... Ir7' /" " r-

l__~~~~~·~tO~" l

Weld facer:':

Full penetration

74 :Structural welding

75

I ~ ~~"', , "7 ~~:~ ~. 8.

I Single "J" Butt Weld

Double "U" Butt Weld • Included angle 20_3Oa

•

Dimensionsas~).• Gap3mm. - 5mrn.• Root thickness 3mm.-5mm.

• Thickness 38 mm. upwards. • Root radius 5mm.-10mm.

• Thickness 25mm • SOmm.

~' ~~'" :\:9. ~~'<~ 10.

,-", <.

Double "J" Butt Weld Single Bevel Butt Weld

Dimensions as(8} • Included angle 45_506

•

Thickness 38 mm upwards. • Gap3mm.-6mm.

Root thickness 1.5mm-3mm.

• Thickness up to 25 mm.

I :>f»:J ~~4~11. v / / 12.!/ / ./[

fu~·Double Bevel Butt Weld Double Bevel Butt Weld

Dimensions as 10 . · Angles as shown.

Thickness 25 mm. upwards.• Gap 1.5 mm-3mm.

• Root thickness 1.5mm-3mrn.

• Thickness up to 38 mm.

Regarding the advantages, the economy, and the defects of eachtype, the following remarks are to be considered:

i- Double - bevel, double - vee, double J and double- V groove weldsare more economical than single welds of the same type because ofless contained volume.

ii- Bevel or Vee grooves can be flame cut and therefore are lessexpensive than J and V grooves which require planning or arc- airgouging.

iii- Single V welding is achieved from one side, it is difficult to preventdistortion, this type is usually economical over 25mm thickness.

Iv- Single U welding is achieved from one side, the distortion is lessthan the single - Vee and is not economical under 19 mm thickness.

v- Double -Vee is a balanced welding with reduced distortion, requiresreversals and is not recommended below 38 mm thickness.

vi- Double - U is a balanced welding with reduced distortion, requiresreversals and is not recommended below 38mm thickness.

vii- Groove welds joining plates of different thicknesses shall preferablybe made with a gradual thickness change not exceeding 1:4 as shownin Fig. 5.3a. for tension members. In compression members there is noneed for a gradual thickness transition.The difference in thickness maybe balanced by a slope in the weld metal rather than machining theparent metal as shown in Fig. 5.3b.

viii- Tee-Groove welds are accepted even if they are not completelywelded achieving a partial penetration groove weld if the total weldthickness is greater than the parent metal thickness, see Fig.5.3C.

Structural welding

Structural welding76 77

welding where all welds are examined to guarantee the efficiency of thejoint as given in Clause 5.9 :

i- Permissible stresses for static loading are shown in Table 5.4 :

Table (5.4) Pennissible Stresses for Static Loading in Groove (Butt)

n,Where F, , F, , and q," are the rmrumurn allowable compressand shear stresses of the base metals.

ii- For fatigue loading, refer to Chapter (3)

WeldsPermissible Stress For

Kind of StressGood Weld Excellent WeldType of Joint

Butt and Compression 1.0 F, 1.1 F,

K- weld -Tension 0.7 F, 1.0 F,

Shear 1.0 qall 1.1 qau

ion tensio

Figure (5.3) Groove Welds for Plates of Different Thicknesses

If these requirements are not fulfilled the Tee-Groove welds are tobe analysed as being fillet welds according to the provisions of Section5.6.

5.5.2.1 The Groove Weld Effective Area

The effective area is the product of the effective thickness dimensiontimes the length of the weld. The effective thickness dimension of a fullpenetration groove weld is the thickness of the thinner part joined asshown in Fig. 5.4a.

~~.~tg= tl

(a)

~Unsealed weld

(b)

Incomplete penetration groove weids and unsealed groove welds arenot recommended, but when it is impossible to avoid their use, theeffective thickness of weld is taken as the sum of the actual penetrateddepths as shown in Fig. 5.4b,c and d.

5.5.2.2 Strength Of Butt (Groove) WeldsIncomplete weld

(c)

Incomplete weld

(d)

The complete joint penetration groove weld is of the same strengthon the effective area as the piece being joined. For permissible stressestwo values are considered; the first for good welds fulfilling therequirements of the specifications, the second value for excellent

Figure (5.4) Incomplete Penetration and Unsealed Welds

Structural welding

Structural weldmg79

78

5.5.2.3 Constructional Restrictions And Remarks 5.6 DESIGN, STRENGTH AND LIMITATIONS OF FILLET WELDEDCONNECTIONS

1. Single V and U groove welds shall be sealed, whenever possible bydepositing a sealing run of weld metal on the back of the joint. Wherethis IS not done. the maximum stress in the weld shall be (except asprovided otherwise below) not more than one half of the correspondingpermissible stresses indicated in Clause 5.5.2.2.

5.6.1 Nomenclature of The Common Tenns

5 5 shows the-nomenclature of the common terms for filletFig..welds.

L penetration~;

Nonnal Throat Size

CONCAVECONVEX

3. When it is Impossible to deposit a sealing run of weld metal on theback of the joint, then provided that backing material is in contact withthe back of the joint, and provided also that the steel parts are beveled toan edge with a gap not less than 3 mm and not more than 5 mm, toensure fusion into the root of the V and the backing material at the backof the joint, the permissible stresses may be taken as specified in Clause5.52.2.

2. In the case of single and double V and U butt weld 18 mm . and overin Size, in dynamically loaded structures. the back of the first run shall becut out to a depth of at least 4 mm . prior to the application of subsequentruns. The grooves thus formed and the roots of single V and U groovewelds shall be filled in and sealed.

4. Possible defects that may result in discontinuities within the weld areto be avoided. Some of the more common defects are: incompletefusion, inadequate joint penetration, porosity, undercutting. inclusion ofslag and cracks (refer to Section 5.8)

5.a- Butt welds shall be built up so that the thickness of thereinforcement at the center of the weld is not less than the following:

Butt welds < 30 mm in size reinforce by 10%Butt welds > 30 mm in size reinforce by 3mm.

b- Where flush surface is required, specially in dynamic loading, thebutt weld shall be built up as given in (a) and then dressed flush.

Figure (5.5) Fillet Weld Nomenclature

Structural weldmg80 Structural welding 81

5.6.2 Different Types of Fillet Welded Connections

Fillet welds are made between plates surfaces which are usually at rightangles. but the angle between the plates may val)' from 60° to 1200

Tee joints. corner welds and cruciform joints are all combinations of fmetwelds and are as shown in Fig. 5.6.

The ideal fillet is normally of the mitre shape which is an isoscelestriangle as shown in Fig. 5.7. (h). The mitre and convex welds arestronger than a concave fillet weld of the same leg length when the weldis subject to static loadings. but the concave is stronger when subject todynamic loadings.

5.6.3 Strength of Fillet Welds

5.6.3.1 Effective Area of Fillet Welds

The effective weld section is equal to the largest triangle which canbe inscribed between the fusion surfaces and the weld surface. providedthere is as a minimum root penetration, this penetration is not taken intoaccount. The effective throat (t) is then the distance from the root to thesurface of the isosceles trianguiar weld along the line bisecting the rootangie as shown in Fig. 5.8.

Vertical welds made upwards in one run, are generally convex.Usually low currents produce the convex welds.

iSi~ ;-,90'

!~~i!

Figure (5.8) Dimensions of Size and Throat of Fillet Weld

Fillet welds are stressed across the throat (t) of the weld, while theirsize is specified by the leg length (s) where:

, kL't"Th~tS 0

--'- 0

,.s.I:,,

Lap-Joint

LOutside Corner Weld

The penetration of the weld should reach the root where the contourof penetration is usually as shown in (g) of Fig. 5.7.

~

Figure (5.6) Combinations of Fillet Welded Connections t = K.s,. .. 5.1

The value of "K" depends on the angle between the fusion faces andit may be taken as follows:

Degree 60' - 90' 91' _100' 101'_106' 07'-113' 114'-120'

K 0.7 0.65 0.6 0.55 0.5(h)

Mitre F,IIel

(f) Obtuse Fillet

_ 0

90

(g)Contour ofPenetration

Figure ( 5.7) Fillet Weld Configurations

(c~Lequa! Unequaleos iegs

(a) (b)Concave Fillet convex F'lIetEqua I Legs Equal legs (e)

~....LLL--L_ AcuteFII~t=~~~:==:j

Slni('/lIrll{ welding

82Structurot welding

83

..

5.6.3.3 Different Limitations Regarding Filfet Welds

5.6.3.2 Strength and Permissible Stresses

All kind of stresses Fpw ,; 0.2 F, 5.2

a- De'posited Fillet Weld Metal

i- The limiting angles between fusion faces for load transmissionshall not be greater than 1200 and not less than:-

- 60° for flat, and down hand welding- 70° for vertical welding- 80° for overhead welding

ii- The minimum leg length of the fillet weld as deposited shall not beless than the specified size. The throat of a fillet weld as deposited shallbe not less than 6/10 and 9/10 of the minimum leg length in the case ofconcave and convex fillets respectively as shown in Fig. 5.9.

~~~

Figure (5.9) Definition of Throat in a Fillet Weld5.3::; 1.1 Fpw

Where F, is the ultimate strength of the base metal (see table 5.1).

f L =the normal stress perpendicular to the axis of the weld.q 11 = the shear stress along the axis of the weld.q L =the shear stress perpendicular to the axis of the weld.

In case where welds are simultaneously subject to normal and shearstresses, they shall be checked forthe corresponding principal stresses.For this combination of stresses, an effective stress value f•• may beutilized and the corresponding permissible weld stress is to beincreased by 10 % as follows:

These stresses shall be related to the size (5) of the legs of theisosceles triangle inscribed in the weld seam if the angle between thetwo surfaces to be welded is between 60° and 90° . When this angle isgreater than 90° the size of the leg of the inscribed rectangularisosceles trianale shall be taken.

The permissible stresses Fpw for all kinds of stress for fillet weldsmust not exceed the following:

The stress in a fillet weld loaded in an arbitrary direction can beresolved into the following components:

b- Size of Fillet Welds

The effective length of a fillet weld is usually taken as the overalllength of the weld minus twice the weld size (5) as deduction for endcraters.

i- The maximum size of fillet weld should not exceed the thickness ofthe thinner plate to be welded.

Structural welding

Structural welding 84 85

No limitations

lh

i/orweldleng

~~

iii- There are no limitations for the length of fillet weld for beam- tocolumn connections as well as for the flange to web weld in welded builtup plate girders (see Fig. 5.11a,b.)

as shown in Fia. 5.10.t (max. of t, or t,) Size s

(mm) (rnrn)< 10 ~4

10-20 ~5

20·30 ~6

30-50 >850-100 >10

It is recommended that the following limitations in sizes of fillet weldsas related to the thickness of the thicker part to be joined should beobserved

ur-

Figure (5.11) Different Locations of Fillet Welds

d- Single Fillet Weld

1~T'iP'

<a) (b) (e)

Figure( 5.10) Thickness or Plates to be Welded

iii- The minimum size of fillet welds is 4 mm for buildings and 6 mm forbridges.

i- Single fillet weld subjected to normal tensile stress perpendicular to thelongitudinal direction of the weld is not to be utilized,(Fig. 5.11c.) .

ii- The single side fillet weld between the flanges and web in I girdersshall be made with a penetration of at least haif the web thickness.

c- Fillet Weld Length

i- The effective length for load transmission should not be less than 4times the weld size (s) or 5 cm whichever is largest.

iii- For the single side fillet flange - to- web weld, this fillet weld shall becompleted on the other side of the web and made symmetrical atsupports, and at the position of concentrated loads where the web is notstiffened by vertical stiffeners.

ii- The maximum effective length of fillet welds should not exceed 70times the size. Generally in lap joints longer than 70 s a reduction factor~ allowing for the effects of non- uniform distribution of stress along itslength rs to be utilized where:

~ =1.2 - 0.2 U (70 s) ..

WhereL = overall length of the fillet weld.~ ,;; 1

5.4

iv- Single side fillet welds may be utilized only for static loads.

e- Intermittent Fillet Weld

i- Intermittent welds shall not be used in parts intended to transmitstresses in dynamically loaded structures.

ii- The clear distance between effective lengths of consecutiveintermittent fillet welds, whether chained (L,) or staggered (L,), shall notexceed 12 times the thickness of the thinner part in compression or 16times in tension and in no case shall it exceed 20 ern. (See Fig. 5.12) .Structural welding

Structural welding 87

86

,- c

--c

- ,--- -

'-

:'-1 ::: =

v- Bridge stiffeners and girder connections are penmitted to be directlywelded with the compression flange. in the case of the tension flange,intermediate plates (not weided to the flange) shall be inserted betweenthe flange and the stiffener in order to prevent weakening of the flangeby transverse welds. Where intenmittent welds are used, the cleardistance between consecutive welds, whether chained or staggered shallnot exceed 15 times the thickness of the stiffener. The effective length ofsuch weld shall not be less than 10 times the thickness of the stiffener inthe case of staggered welds and 4 limes in the case of chained welds, orone quarter the distance between stiffeners whichever is smallest.

The stress transfer of plug and slot welds is limited to resisting shearloads in joints at planes parallel to the faying surface. The shearcapacity is calculated as the product of the area of the hole or slot andthe design shear stress as is previously mentioned in Clause 5.5.3.2.(Equations 5.2 and 5.3)

5.7 PLUG AND SLOT WELDS

iv- For a member in which plates are connected by means of intermittentfillet welds, a continuous fillet weld shall be provided on each side of theplate for a length (L 0) at each end equai to at least three quarters of thewidth of the narrower plate connected (see Fig. 5.12) .

For staggered welds this applies generally to beth edgJ's but neednot apply to subsidiary fittings or components such as intenmediatestiffeners.

iii- In a line of intermittent filiet welds, the welding shali extend to theends of the connected parts.

The proportions and spacing of holes and slots and the depth areillustrated in Fig. 5.13. - L 0 2: 0.75 b or 0.75 b, - whichever is smaller

_(L,) or (L,) s 15 t or 15 t, or 200 mm - whichever is smallest (Tension)

-(Lilor (L,l< 12t or 12t, or 200 mm-whi.;hever is smallest (Comoression)

Figure (5.12) Intenmittent Fillet Welds

Strncrural welding

88 Structural welding

89

5.8 GENERAL RESTRICTIONS TO AVOID UNFAVOURABLEWELD DETAILS

iii- The use of a welding procedure with low hydrogen weld and aneffective preheating minimize lamellar tear.

ii- The welding procedure should also establish a welding sequencesuch that the component restraint and the internal restraints in theweldment are held to a minimum.

i- Using small weld size providing the shrinkage to be accommodated.

Lamellar tearing is a separation (or crack) in the base metal. causedby through - thickness weld shrinkage strains.The probability of thisfailure can be minimized by:

5.8.1 Lamellar TearingR

R

p

~:

p

d"- I- ! /' !

)J .L, '-1.-, /

1y • T T1 !

'I i I-- I ,

p

Figure (5.13) Definition of Plug and Slot Welds Some joints susceptible to lamellar tearing can be improved by carefuldetailing as shown in Fig. 5.14. .

Improved detail

Plate Min. HoleThickness dia or Slot Hole and Slot Proportions Spacing and

t (mm) width dm1n Depth of Weld(mm)

d 2: (t+8)mm preferabiy rounded to5&6 14 next higher odd 2 mm; also d S 2.25 t

or dm1n +3mm whichever is oreater

7&8 16 P 2: 4d

9 &10 18pi 2: 21 Depth of filling of plug and

IS 10 w slot welds (w):

11 & 12 20Where t S 16mm, w =t

R = dl2 Where t 2:16mm, w=U2

13&14 22 R 2: t but not less than 16 mm.

15 &16 24

N.B. There are no limitations for the edge distances.

Suspectible detail

(e)Figure ( 5.14) Improved Welded Connections to Reduce

Lamellar Tear

Structuralwelding

Structural wetding 9190

5.8.2. Notches and Brittle FractureTable (5.5) Characteristics of Common Weld Inspection

Methods

5,9 WELD INSPECTION METHODS

Figure (5.15) Notches and Brittle Fracture

Inspection Characteristics and LimitationsMethod Applications

Mostcommon, most Detects surface imperfectionsVisual (VT) economical. Particularly good only.

for sirn:lte ease.

Detects surface imperfectionsonly.

Dye Penetrant Will detecttightcracks. opento Deepweldripplesand(OPT) surface. scratchesmaygivefalse

indications.

Will detectsurfacecracks and Requiresrelatively smoothsubsulfacecracks to about2 surface.

Magnetic mmdepth withproper Carelessuseof magnetizationParticle (MT) magnetization. prodsmayeeve false

Indications can be preservedon clearclastic tece.

indications.

Detectsmustoccupy morethan about 11/S%of

Detectsporosity, slag,voids, thicknessto register.Radiographic irregularities, lackof fusion. Only cracks partialto

(RT) Filmnegative is permanent impingingbeamregister.record. Radiation hazards

Exposure time increases withthickness.

Detects cracksin anyorientation, Surfacemust be smooth,Slag, lackof fusion, inclusions, Equipment must be frequentlylamellar tears, voids. calibrated.

UltrasonicCandetecta favorably Operator must be qualified.oriented planarreflector Exceedingly coarsegrainswill

(UT) smaiierthan1mm. give false indications.Regularly calibrateon 1 % mm certain geometricdiadrilledhole. configurationsgive falseCanscan almostany indicationof flaws.commercial thickness.

Backing

ba,(b)

(0)

Weld metal

c-----+;.-..•.~

Tacks are incorporated

in weld

Strong

(01

Notch

i--------'

Weak

The designer must specify in the contract document the type of weldinspection required as well as the extent and application of each type ofinspection.

ii- Backing bars can cause a fatigue weld notch if they are welded asshown in Fig. 5.15b. A remsdy would be to weld in the groove as in Fig.5.15c, where any undercut would be filled, or at least backed up by thefinai weld joint. The backing bars should also be continuous throughoutits length.

i- The one sided fillet welds can result in severe notches as shown in Fig.5.15a. The remedy is to use two fillets one on each side. A similarcondition arises with partiai penetration groove welds.

Table 5.5 summarizes the characteristics and capabilities of the fivemost commonly used methods for welding inspection.

Structural welding

92 93Structural welding

CHAPTER 6

BOLTED CONNECTIONS

6.1 MATERIAL PROPERTIES

6.1.1 Non- Pretensioned Carbon and Alloy Steel Bolts6.1.3 Rivets

The rivet steel is a mild carbon steel and is available in two gradesnamely grade 1 and grade 2 where the corresponding ultimate tensilestrength (F,,) is 5.0 Vcm' and 6.0 Vcm', respectively.

Structural riveting has essentially been replaced by welding andbolting. Taken space to the rivet is given for reference to dimensionsfor assistance in modifying older exlstinq buildinqs.

6.2.1 1'10les

i- Holes for bolts may be drilled or punched unless specified.

ii- Where drilled holes are required, they may be sub- punched andreamed.

iii- Slotted holes shall either be punched in one operation, or elseformed by punching or drilling. Two round holes are completed byhigh quality flame cutting, and dressing to ensure that the bolt canfreely travel.

6.2.2 Clearances in Holes for Fasteners

i- Excepi for fitted bolts or where low- clearance or oversize holesspecified, the nominal clearance in standard holes shallbe:-

1 mm for M12 and M14 bolts2 mm for M16 up to M24 bolts3 mm for M27 and larger

6.2 HOLES, CLEARANCES, WASHERS AND NUTSREQUIREMENTS

6.1.2 Pretensioned High Strength Bolts

High strength bolts of grade 8.8 and 10.9 are mainly used aspretensioned bolts with controlled tightening, where the forces actingtransverse to the shank are transmitted by friction (slip), and mustconform with requirements of section 6.5.

Grade 8.8 is of heat - treated high strength steel and Grade 10.9 isalso of heat - treated, but is of alloy steel.

Bolts of 9rades 4.6 up to 6.8 are made from low or mild carbonsteel. and are the least expensive type of bolts for light structures.

Bolts of grades lower than 4.6 or higher than 10.9 shall not beutilized.

These bolt grades are used in conjunction with structuralcomponents in steel up to St 52.

Table (6.1) Nominal Values of Yield Stress Fyb and UltimateTensile Strength F b for Bolts

For non - pretensioned bolts, where the forces acting transverseto the shank of the bolt are transmitted either by shear or bearing, the

nominal values of the yield stress Fyb and the ultimate tensilestrength FUb are as given in Table 6.1 :-

0

Bolt grade 46 4.8 5.6 5.8 6.8 8.8 109

FYb (Vcm') 2.4 3.2 30 4.0 4.8 6.4 9.0

Fob (Vcm') 4.0 4.0 50 5.0 6.0 8.0 10.0

Botted Connections 94SoltedConnections 95

ii- Holes with 2 mm nominal clearance may also be specified for M12and M14 bolts provided that the design meets the requirementsspecified In Clauses 6.4.1 and 6.4.2.

iii- Unless special clearances are specified, the clearance of fittedbolts shall not exceed 0.3 mm.

6.2.3 Nuts Constructional Precautions

i- For structures subject to vibration, precautions shall be taken toavoid any loosening of the nuts.

ii- If. non- pretensioned bolts are used in structures subject tovibrations, the nuts should be secured by locking devices or othermechanical means.

iii- The nuts of pretensioned bolts may be assumed to be sufficientlysecured by the normal tightening procedure.

6.2.4 Washers Utilities

[; Washers may not required for non-pretensioned bolts except asfollows:-

- A taper washer shall be used where the surface is inclined atmore than 3 0 to a plane perpendicular to the bolt axis.

- Washers shall be used where this is necessary due to arequirement to use longer bolt in order to keep Ihe bolt threads outof a shear plane or out of a filted hole.

ii- Hardened washers shall be used for pretensioned bolts under thebolt head as well as under the nut, whichever is to be rotated.

6.2.5 Tightening of Bolts

i- Non-pretensioned bolts shall be tightened suffiCiently to ensure thatsufficient contact is achieved between the connected parts.

ii- it is not necessary to tighten non-pretensioned bolts to themaximum tightening value given in Clause 6.5.3. However as anindication, the tightening required should be:

_That which can be achieved by one man using a nonmal prodgerspanner or

- Up to the point where an impact wrench first starts to impact.

iii- Pretensioned bolts shall be tightened in conformity with Clause6.5.3

6.3 POSITIONING OF HOLES FOR BOLTS AND RIVETS

6.3.1 Basis

i- The positioning of the holes for bolts and rivets shall be done suchas to prevent corrosion and local buckling, and to facilitate theinstallation of the bolts and rivets.

ii- The positioning of the holes shall be also in conformity with thelimits of validity of the rules used to determine the design bearingstrength of the bolts and the rivets as given in Clause 6.4.2.

6.3.2 Minimum End Distance

j_ The end distance e, from the center of a fastener to the adjacentend of any steel element, measured in the direction of load transfer(Fig. 6.1) should not be less than 1.5d, where d is the nominal boltdiameter.

ii. The end distance should be increased if necessary to provideadequate bearing resistance (Clause 6.4.2) .

6.3.3 Minimum Edge Distance

The edge distance ez from the center of a fastener to the adjacentedge of any steel element, measured at right angles to the directionof load transfer (Fig. 6.1) should not be less than 1.5d.

Bolted Connections 96Bolted Connections 97

t= jhe smallest connected thickness

.. .CompreSSIon

6.3.4 Maximum End or Edge Distance

The maximum end or edge distance shall be 12 times the thickness(t) of the smallest connected part under consideration.

6.3.5 Minimum Spacing

i- The spacing (s) between centers of fasteners in the direction ofload transfer (Fig. 6.1) should not be less than 3d.

ii- The spacing (g) between rows of fasteners, measuredperpendicular to the direction of load transfer (Fig. 6.1) shouldnormally be not less than 3d.

6.3.6 Maximum Spacing in Compression Members

The spacing (s) of the fasteners in each row and the spacing (g)between rows of fasteners should not exceed the lesser of 14t or 200mm. Adjacent rows of fasteners may be symmetrically staggered(Fig. 6.2).

6.3.7 Maximum Spacing in Tension Members

In ten~jon _members the center - to - center spacing .211,i offasteners In Inner rows may be twice that given in Clause 6.3.6. forcompression members, provided that the spacing .£f,.c in the outerrow along each edge does not exceed that given in Clause 6.3.6(Fig. 6.3) .

5 ~ 141andl~ 200mm :6 1,! I

~. -El--- ,-~-4--r,Direction of ' , I I9

.. load IranSf.';" ---T -4--~-? -- - ~ _L

r i \'-t----j--'1= The! smallest connected thfckn 5S

Figure (6.1) Spacing in Tension or Compression Members

1>--__.-+.,.,"''''< 14tand 5 200mm

,s > 3d

Figure (6.2) Staggered Spacing - Compression

I I ,.11o~ 14tand ~ 200mmI I'

outer ro~f- -4-1

- ~t==-=t-----:;;-,H2Bt and' 400mm

Inner row_ - -- - J;=--- --- -4= ~i.. ~---rAilS of symmetry-+- Tenslon--

t= The smallestconnected thickness

Figure (6.3) Maximum Spacing in Tension Members

6.3.8 Slotted Holes

i-The minimum distance (e3) from the axis of a slotted hole to theadjacent end or edge of any steel element should not be less than

1.5d (Fig.6.4).

il- The minimum distance (ea) from the center of the end radius of aslotted hole to the adjacent end or edge of any steel element should

not be less than 1.5d (Fig. 6.4) .

Bolted Connections 98Bolted Connections 99

l

6.3

6.2

RSh = qb . As .n

q. = 0.2 F'b

iii- For the determination of the design shear strength per bolt (R,,) ,where the shear plane passes through the threaded portion of thebolt:-

jj_ For bolt grades 4.8, 5.8 , 6.8, and 10.9, the allowable shear stressqb is reduced to the following:-R

p

! I I !i=- I R

i -L .L,

-,dT d!"---' 0

!Pi:

,

I

l

iv- For bolts where the threads are excluded from the shear planesthe gross cross sectional area of bolt (A) is to be utilised.

v- The values for the design of shear strength given in Equations 6.1and 6.2 are to be applied only where the bolts used in holes withnominal clearances not exceeding those for standard holes asspecified in Clause 6.2.2.

~-----'t-------,

eI !--'-~--j

~~:-+J-"3 1

I tJI· 0.5d

Where:A. =n =

The tensile stress area of bolt.Number of shear planes.

Figure ( 6.4) End and Edge Distances for Slotted Holes

6.4 STRENGTH OF NON-PRETENSIONED BOLTED CONNECTIONSOF THE BEARING TYPE

vi- M12 and M14 bolts may be used in 2mm clearance holesprovided that for bolts of strength grade 4.8., 5.8, 6.8 or 10.9 thedesign shear stress is to be reduced by 15%..

6.4.2 Bearing Strength Rb

i- The bearing strength of a single bolt shall be the effective bearingarea of bolt times the allowable bearing stress at bolt holes:-

In this category ordinary bolts (manufactured from low carbonsteel) or high strength bolts, from grade 4.6 up to and including grade10.9 can be used. No pre- tensioning and special provisions forcontact surfaces are required. The design load shall not exceed theshear resistance nor the bearing resistance obtained from Clauses6.4.1 and 6.4.2. Rb = Fb .d. min It . 6.4

6.1

6.4.1 Shear Strength R'h

i· The allowable shear stress q, for bolt grades 4.6, 5.6 and 8.8 shallbe taken as follows:

q, = 0.25 F'b

Where:Fb

dMin It

= Allowable bearing stress.= Shank diameter of bolt.= Smallest sum of plate thicknesses in the same

direction of the bearing pressure.

Boited Connections 100 Bolted Connections 101

Table (6.2) Values of a for Different Values of End Distance

As the limitation of deformation is the relevant criteria the a-valuesof Equation 6.5 are given in Table 6.2.

ii~ For distance center- to center of bolts not less than 3d, and for enddistance in the line of force greater than or equal to 1.5 d, theallowable bearing stress Fb (tlcm'):

R La

= The actual shearing force in the fastener due tothe applied shearing force.

= The actual tension force in the fastener due to theapplied tension force.

= The allowable shear and tensile strength of thefastener as previousiy given in Equations (6.3)and (6.6) respeclively.

6.5 HIGH'STRENGTH PRETENSIONED BOLTED CONNECTIONSOF THE FRICTION TYPE

6.5.1 General

Where:Rsh,a

6.5

Where:

F, = The ultimate tensile strength of the connected plates.

Fb = a Fu '" ..

6.4.3 Tensile Strength R,

When bolts are externally loaded in tension, the tensile strength ofa single bolt (R,) shall be the allowable tensile bolt stress (Fib) timesthe bolt stress area (As)

End distance in direction of force

" 3d " 2.5d " 2.0d " 1.5d

a 1.2 1.0 0.8 0.6

R,With Fib

= Ftb .s;= 0.33 FUb

6.66.7

'In this category of connections high strength bolts of grades 8.8and 10.9 are oniy to be utilized. The baits are inserted in clearanceholes in the steel components and then pretensioned by tighteningthe head or the nut in accordance with Clause 6.5.3 where adetermined torque is applied. The contact surfaces will be firmlyclamped together particularly around the bolt holes.

Any applied force across the shank of the bolt is transmitted byfriction between the contact surfaces of the connected components,while the bolt shank itself is subjected to axial tensile stress inducedby the pretension and shear stress due to the applied torque.

6.5.2 Design Principles of High Strength Pretensioned Bolts

6.5.2.1 The Pretension Force

6.4.4 Combined Shear and Tension in Bearing-Type ConnectionsThe axial pretension force T produced in the bolt shank by

tightening the nut or the bolt head is given by:- .When bolts are SUbjected to combined shear andfollowing circular interaction Equation is to be satisfied:

(~) 2 + [~J2S1R sh R t

tension, the

6.8 Where:FYb =As =

Yield (proof) stress of the bolt material, (Table 6.1).The bolt stress area. \ .'

Bolted Connections 102 Bolted Connections 103

6.5.2.4 Design Strength In Tension Connections

bolt and the service load joint shear are such that the coating willprovide satisfactory performance under sustained loading.

6.5.2.3. The Safe Frictional Load (Psl

Where the connection is subjected to an external tension force(Text) in the direction of the bolts axis, the induced extemal tension

force per bolt(Text,b) is to be calculated according to the followingrelation:-

The design frictional strength for a single bolt of either grade 8.8or 10.9 with a single friction plane is derived by multiplying the boltshank pretension T by the friction coefficient ~ using an appropriate

safety factor y as follows:-Ps = ~ T I y 6.10

The total number of baits resisting the external tensionforce T(ext)

T(ext,bl = T(exI)t a «0.6 T......... 6.11

=

=

Where:n =

Axial pretensioning force in the bolt.Friction coefficient.Safety factor with regard to slip.1.25 and 1.05 for cases of loading I and II respectivelyfor ordinary steel work.1.6 and 1.35 for case of loading I and II respectively forparis of bridges, cranes and crane girders which aresubjected mainly to dynamic loads,

Table 6.3 gives the pretension force (T) and the permissible

frictionai load (Ps) per one friction surface for bolts of grade 10.9.

Where:T =~ =y =

In class A:- Surfaces are blasted with shot or grit with any loose rustremoved, no painting.- Surfaces are blasted with shot or grit and spray metallized with

Aluminium.-.Surfaces are blasted with shot or grit and spray metallized with a

Zinc based coating.

In class B:- Surfaces are blasted with shot or grit and painted with an alkali­zinc silicate painting to produce a coating thickness of 50-80 urn.

In class C:- Surfaces are cleaned by wire brushing, or fiame cleaning, withany loose rust removed.

ii- The design value of the friction coefficient depends on thecondition and the preparation of the surfaces to be in contact. Surfacetreatments are classified into three classes, where the coefficient offriction ~ should be taken as follows:-

~ = 0.5 for class A surfaces.~ = 0.4 for class B surfaces.~ = 0.3 for class C surfaces.

6.5.2.2 The Friction Coefficient or The Slip Factor" p"

i-. The. friction coefficient between surfaces in contact is thatdimensionless value by which the pretension force in the bolt shank isto be. multiplied in order to obtain the frictional resistance Ps in thedirection of the applied force.

iii- The friction coefficient ~ of the different classes is based on thefollowing treatments:

iv- If the coatings other than specified are utilized, tests are requiredto determine the friction coefficient. The tests must ensure that thecreep deformation of the coating due to both the clamping force of the

BoJred Connections104 Bolted Connections 105

6.13

6.12

T +P<O.8Tt ext,b -

1p= Prying force

107

I' (T - Text,b)

T\e"'.b) + P S 0.8 T

t

Figure (6.5) Prying Force

T +-P<O.8Text.b - t

pe Prying force I

Balled Connections

In connections subjected to both shear (0) and tension (Text), thedesign strength for bolt is given by the following formulae:-

6.5.2.5 Design Strength in Connections Subjected to CombinedShear and Tension

The prying torce (P) depends on the relative stiffness and thegeometrical configuration of the steel element composing theconnection. The prying force should be determined according toClause 6.9 and hence the following check is to be satisfied:-

In addition to the applied tensile force per bolt T(exl.b) • the boltshall be proportioned to resist the additional induced prying force (P)(Fig. 6.5).

~•0M>-.c

"C.,0:::l"C.,~

e:- .c

t- O;.::

"- '"" '"• "e, :::l0;>e

~ >0,; .c

N.,

.,; .,s:

" -• co::; .;

<.,

"Ch ..

~~

'"u.;:::- 01

I/)e. :x:

"~

0t- U.

~""Il)MMcn_,....COlO "lfOLl')IOItD"l'""

c:i ~ N M Ml-.:t ..n cO

Bolt Area(A) em'

~: I(J) I Pretension en i en M co M _ ~ r-...

NCO~~<"!~~"I:t;"C r!OrCe tti aillO 0') N co l.l) _,

; Tl tons """ - ('II N M It)!

e"-toui

~ Stress Areat: (A,) em'1:

lI

6.5.2.6 Design Strength in Connections Subjected to CombinedShear and Bending Moment

The induced maximum tensile force T(ext.b,M) due to the appliedmoment (M) in addition to the prying force P that may occur, mustnot exceed the pretension force as follows:-

6.16r

11 (T - T.",-o)

6.5.3 Bolting Procedure and Execution

Bolts inay be tightened by calibrated wrenches, which canindicate either the applied torque or the angle of rotation of the nut.

i- For the first method, torque wrenches which have a cut-out-deviceto limit the required amount of the applied torque must be employed.Wrenches may be of the manual, pneumatic, or electric-type. Thetorque "M," (Table 6.3) required to induce the pretensioning force "T"shall be calculated as follows:

6.14

6.15

r-rr-

Tlext.b,M) • P ,; 0.8T

In moment connections of the type shown in Fig. 6.6, the loss ofclamping forces in region "A" is always coupled with a correspondingincrease in contact pressure in region "B". The clamping forceremains unchanged and there is no decrease of the frictionalresistance as given by the following :_

Pe ~ 11 T . y

Q

A

isI

)~..

I

Where:Ma ;;;

k =d =T =

Ma = k.d.T

Applied torque.Coefficient (about 0.2 for all bolts diameters)Diameter of bolt.Bolt pretension force.

6.17

Figure (6.6) Connections SUbjected to Combined Shear andBending Mome,lt

6.5.2.7 Design Strength in Connections SUbjected to CombinedShear, Tension, and Bending Moment

When the connecuon is SUbjected to shearing force (0), a tensionforce (Text ) and a bendinq moment (M). the design strength per boltis to be according to rhe following formulae:-

Bolted Conuecaans108

ii- The second method of tightening is based on a predeterminedrotation of the nut. The tightening can be achieved in different waysas follows:

a- The parts to be joined are first brought into contact bymaking the bolts snug tight by a few impacts of an impactwrench. Following this initial step each nut is tightened one halfturn.

b- The bolt is first tightened using a wrench until the severalplies of the joint achieve a " snug fit" after which the nut isfurther turned by the amount:-

Bolted Connections 109

1,

The contact surfaces must be free from dust, oil, paint, etc. Spotsof oil cannot be removed by flame cleaning without leaving harmfulresidues, and must be removed by chemical means. It is sufficient toremove any film of rust or other loose material by brushing with a softsteel brush.6.5.5 Protection Against Corrosion

6.5.4 Preparation of Contact Surfaces

a=900+t+d _.. 6.5.6.2 Friction Coefficient Check

It is desirable to make random checks of the friction coefficientachieved by surface preparation.

6.19q, =0.4 Fy

6.6 ALLOWABLE SHEAR RUPTURE STRENGTH

At beam end connections, where the top flange is coped and forsimilar situations where failure might occur by shear along a planethrough the' fasteners or by a combination of shear along a planethrough the fasteners plus tension along any perpendicular plane Atsuch as the end of a beam web or as thin bolted gusset plates insingie or double shear (Fig. 6.7) the allowabie shear stress ofChapter (2) acting on the net shear area A'h is to be increased by15% :

6.18

Rotation in degrees.Totai thickness of connected parts in mm .Bolt diameter in mm.

atd

Where:

Figure (6.7) Failure by Tearing Out of Shaded Area

Furthermore, the allowable tensile strength on the net tension areaAt is to be increased by 25% :

FIr =0.725 Fy 6.20

J

J

ii- The position of the nut on the bolt which is to be checked ismarked. The bolt is then held firmly and the nut is unscrewed by1/6 of a complete turn. To turn the nut back to its originaiposition, it must be necessary to apply the specified torque.

i- The bolt is turned a further 10° for which at least the specifiedtorque has to be applied.

Parts to be joined with high strength bolts of the friction type mustbe protected against corrosion, by suitable protection against entry ofhumidity between the contact surfaces as well as the bolt holes.

6.5.6.1 Tensioning Force

6.5.6 Inspection

One of the following two procedures may be adopted to check thatthe specified torque "Ma" has been applied:-

For structural components, where the contact surfaces have beenprepared for a prestressing process, and are stored for long periods,there is a risk of rusting. An inspection regarding the coefficient offriction is essential.

Bolted Connecunns110 Bolted Connections 111

6.7 ADDITIONAL REMARKS

6.7.1 Long Grip

iii- In case of high strength bolts of grades 8.8 and 10.9 hardenedwashers should be used for single lap joints with only one bolt.

Figure (6.8) Long joints

i- Bolts of grade 4.6 and 4.8, which carry calculated stresses fulfillingsection 6.4 with a grip exceeding 5 times the bolt diameter (d) shallhave their number increased 1% for each 1 mm increase in the grip.

ii- This provision for other grades of bolts shall be applicable only withgrip exceeding 8d.

6.7.2 Long Joints

i- Where the distance L, between the centers of end fasteners in ajoint, measured in the direction of the transfer of force (Fig. 6.8) ismore than 15d, the allowable shear and bearing stresses qb and Fb ofall the fasteners calculated as specified in Clauses 6.4.1 and 6.4.2shall be reduced by a reduction factor BL given by the following:

1.0,,--,-.._

0.8 0.75------------ ------

0.6 i0.4

0.2

15d 65d

I. Lj

Long joints

• I

BL

= 1- L,-15d200 d 6.21

Where 0.75' BL s 1.0 Figure (6.9) Single Lap Joint With One Bolt

6.23

i- Where bolts transmitting load in shear and bearing pass throughpackings of total thickness tp greater than one-third of the boltdiameter d, the allowable shear stress calculated as specified inClause 6.4.1 shall be reduced using a reduction factor Bb as follows:-

s,=~ Where Bb 5 18d+3tp

6.7.4 Fasteners Through Packings

i- In single lap joints with only one bolt, (Fig. 6.9) the bolt shall beprovided With washers under both the head and the nut to avoid oun­out failure

ii- Thrs provision is not to be applied, where there is a uniformdistnbution of force transfer over the length of the joint such as thetransfer from the web of I section to the column flange.

6.7.3 Single Lap Joints with One Bolt

ii· The bearing strength determined in accordance with Clause 6.4.2shall be limited to :

Rh 5 0.75 F,. d.tBolted Connections 112

6.22ii- For double shear connections with packings on both sides of asplice, to should be taken as the thickness of the thicker packing.

Bolted Connections 113

6.7.5 Anchor Bolts and Tie Rods

The allowable shear and tensile stresses through the threadedportion as prescribed in Clauses 6.4.1 and 6.4.3 are restricted tobolts of different grades.

6.9.2 Determination of The Prying Force P

In order to determine the prying force P, the connection is to betransformed to an equivalent Tee stub connection as shown in Fig.6.11. The prying force P can be determined using the follOWingrelation :-

For other threaded parts with cut threads as anchor bolts orthreaded tie rods fabricated from round steel bars, where the threadsare cut by the steelwork fabricator and not by a specialist boltmanufacturer, the allowable shear and tensile stresses given byEquations 6.1 and 6.7 are to be decreased by 15% .

6.8 HYBRID CONNECTIONS

1 wtp4

2 30ab2A.

( 3aX~ + 1) + wtp44 4b 30ab2A

s

6.24

i- When different forms of fasteners are used to carry a shear load, orwhen welding, and fasteners are used in combination, then one formof connector shall normally be designed to carry the total load.

ii- As an exception to this provision, prestressed high- strength boltsin connections designed as a friction type may be assumed to shareload with welds, provided that the final tightening of the bolts iscarried out after the welding is completed.

6.9 THE DETERMINATION OF THE PRYING FORCE (P) FORPRESTRESSED HIGH STRENGTH BOLTED CONNECTIONSSUBJECTED TO TENSION AND lOR BENDING MOMENT

6.9.1 Configuration

(Fig. 6.1Ga, b and c) illustrate the most common types ofconnections, where the outer overhangings may press on theircorresponding supports causing the prying force "P". The pryingaction depends on the fleXibility of the Tee stub flange, and the endplate which is denoted in (Fig. 6.1Oa, b and c) by the thickness (tp) .

Where:a,b =

w =

A. =Tellt,b' =Texl,b,M

Where

Bolt outer overhanging and inner bolt dimension withrespect to the stem Tee stub respectively in cm.Flange Tee stub breadth with respect to one column ofbolts.Bolt stress area.Applied external tension force on one bolt column dueto either an applied external tension force Te" (Fig.6.1Ga) or due to the replacement of the appliedmoment (M) by two equal external and opposite forces

MI'Tb=Cb= - (Fig.6.1Gb)orduetoanexactanayslsdb

of an end plate moment connection (Fig. 6.1Oc)

T ext,b = Text ( Fig. 6.1Ga)4

Text,b,M ;;;;Tb (Fig.6.1Gb)4

Bolted Conneclions114 Bolted Connections 115

(b) Tee- Stub

(a) Welded flange

Text orT b

i'

+ +

+ +

+ +

+ ii+

,

, ,P+Tbi4

,'''b

l'0drTb

Cb

Tb=Cb=Mld b'--

I 'II w!

Eq~lvalentTee stubr----

(b) Tee stub moment connection

t

1

rf?~~±h~f:

f

(a) Beam to beam connectionin orthogonal dimensions

1f----

(d) Corresponding BendingMoment

(c) Deflected Shape

Text orT b

I~\~I ~=P"IIA.."~,I~

fv\.2=P,a ~ (Text.b or T ext,b,M ),b

'I:+!i +

+ +

+ +

I,

If.. ~

Text,b,M +P - 1-" tb-",

I

o'!iTb

Texl.bM+P C, .-

t-

I

(C) End plate moment connection

Figure (6,10) Common Types of Connections Producing PryingForces

Figure (6.11) Equivalent Tee Stub Connection

6.9.3 Determination of The Tee Stub or The End Plate Thickness

(t p)

Bolted Connections116

a- The ideal situation shown in Fig. 6.12 is to place the rows of boltsat A-A and B-B as close as possible to the tension flange with notBolted Connecttons 117

! I. i

more than two bolts per row otherwise the uniform distribution offorces can no longer be valid.

be A row of bolts near the beam compression flange at C-C is to beutilized in order to prevent this part from springing.

c- Compute an approximate end plate thickness using the modelshown in (Fig. 6.12b) or using the following relation:

t p = 0.613

Half breadth of end plate = half breadth of Tas-stub• flange.Wfor case of two columns of bolts.=

=

Text,.,M + P ~ 0.8 T , 6.28

6.9.4 Safety Requirements for Beam to Column Connections

i. Column web' at the vicinity of the compression beam flange" crippling of the column web" :

Crippling of the column web is prevented if :

t :> ""t., 6.29we t.,+2t" +5k

Where

w

w

M(2b+2s+tb }

db W r,

Beam momentInternal distance with respect to the Tee- stub web orto the beam flange.

Where:M =b =

If Equation 6.29 is not satisfied, use a pair of horizontal stiffenersfulfilling the following condition:

= Fillet weld size.= Flange beam thickness and depth. (db= h - tb)= Height of beam cross section= Allowable bending stress of end plate steel material. 2bsttst :>""tb -(t., +2t" +5k}twe . 6.30

d- Compute the induced prying force P using Equation 6.24 wherethe end plate thickness corresponds to step (c).

In order to prevent the local buckling of these stiffeners:

e- Compute the exact induced bending moment in the end plate asfollows (Fig. 6.12c)

f· Hence compute the exact required end platesafety of bolts, using the following two Equations:

!6(gre.ter of M, or M2)t p = 11

V 2w Fb

If Equation 6.32 is not satisfied, use a pair of horizontal stiffenersfulfilling the condition of Equation 6.30:

6.32

6.31

............ " , .

. b fl ge" bendingii. Column flange at the location of the tension eam anof the column flange ": .Bending of the column flange is prevented if:6.26

6.27

thickness and the

}M, = P.a

M2 =P.a - Text,b,M .b

Boiled Connections 118Bolted ConnectIOns 119

=""...

a. a doubler plate to lap over the web to obtain the total requiredthickness.

b- a pair of diagonal stiffeners in the direction of the diagonalcompression having the following dimensions:

EQu.6,30

E 11.630

•

•

to

ICEJl\OOl

ld) Distortion of beam to column conneetio

p

p

Equivalent Teestub

EQuivalenl Tee slull;

rr::

(bl Approximate endplate model

k {a) Configuration

}-~6.34

6.33

2b"tst =[(M /q,) - (0.35 Fy ) he twcl/(0.58 Fy cos 8) .

tw e ~ (M /q,) I [ (0.35 Fy ) he 1

If Equation 6.33 is not satisfied, use either a or b :

iii. Distortion of the web at beam to column connection:

Distortion of the column web is prevented if:'

2b+ZS +t b

."sJi.. ,~~+S)

••

e=- EdgeDistancep= Pitch

~"' ,, .', t,, .a ,

l"p

Bolted Connections 120

Figure (6.12) Determination of The Tee Stub or The End Plate

Bolfed Connections 121

c. If a girder panel is subjected to simultaneous action of shear andbending moment with the magnitude of the shear stress higher than0.6 qb .according to Equations 2.8. 2.9 and 2.10, the allowable

bending stress shall be limited to :

CHAPTER 7

PLATE GIRDERS FOR BUILDINGS AND BRIDGES

7.1 GENERALFb = [0.8 - 0.36 (qact I qb )] Fy

.................. 7.3

Plate G.irders for Buildir;gsand Bndges 122

7.4...........................tw~ d,Jl; 1145> dl120

Grade lw~

of Steel t~ 40 mm40 mm < t ~ 100 mrn

St 37 d/120 d/130

St44 d1110 d1120

St 52 d1100 d1105

7.3.3 Girders Stiffened LongitudInally

a. The web plate thickness of plate girders with longitudinal stiffeners(with or without transverse stiffeners), placed at d/5 to d/4 fromcompression flange. shall not be less than that determined from:

Plate Girdersfor Buildings 123and BridgeS

b. Where the calculated compressive stress foe equals the allowablebending stress Foe, the thickness of the web plate shall not be less

than:lw~d.JFY/190 7.5

a. The web plate thickness of plate girders wtthout longitudinalstiffeners (with or without transverse stiffeners) shall not be less than

that detemined from:

Alternativeiy, the cross section may be designed assuming theflanges alone can resist the total bending moment in the girderwithout reducing the allowable bending stress.

7.3.2 Girders not Stiffened Longitudinally

7.1

.for(d/lwl~159/JFY

qb = [1.5 - (d/lwl JFY 1212)[0.35 FYI s 0.35Fy

- for (d/twl > 159/ JFY

qb = {119f[ (d/twl JFY I }{0.35 Fy} .............. 7.2

b- When transverse stiffeners are .that the actual shear stress will US~d, their spacing shall be suchEquations 2.8. 2.9 and 2.10. I no exceed the value given by

.Plate girder sections with no-Iar .usmq the moment of inertia m th ge openings shall be designedratiO,(d/t

w) should not exceed 8;0/~d. The web heiqht-to-thickness

tlcm , and the mini.num thickne y; where Fy

IS the yield stress inbuildings and 8 mm for brid ss a component plate is 5 mm for

ges.

7.2 ALLOWABLE STRESSES & EFFECTIVE CROSS·SECTIONS

The allowable stresses used for d .are as specified in Clause 26Th ;slgn of plate girder sectionsslender elements shall be ca'lcul t ~ e active cross-sectional area of

a e according to Clause 2.6.5.5.

7.3 WEB PLATE THICKNESS

7.3.1 Girders with Transverse Stiffeners

a· Transverse intermediate stiffenaverage calculated shear stress in ers shall be used when theIS larger than the value obtain d f the gross section of the web platewith k

q= 5.34: i.e.. e rom Equations 2.8. 2.9. and 2.10

tw " d,Jt;;; /'240 > d/240

= Maximum vertical shear at the stiffener position

= The buckling shear stress

7.6

b- W~ere the calculated compressive stressbending stress Fbc the thi k fbe equals the allowablethan: ,IC ness of the web plate shall not be less

Where:

Qaetq.

0.35 Fyc, =0.65 ( -1) Q.ctqb

......................... 7.8

7.4 WEB STIFFENERS

7.4.1 Transverse Stiffeners

i- Inte~medjate transverse stiffeners F .one stiffener connected on each slde Ig. 7.1, may be In pairs, i.e.;at the compression flange. They ma o~ the web plate, with a tight fitstiffener connected on one side of thY' owever, be made of a single

e web plate.

~i- Be~ring stiffeners at points of c .In pairs with tight fit at both fla~~~entrated loading shall be placedcolumns on the applied force or re - t

S, and should be designed as

ac Ion at the stiffener position

iii- The outstand of the stiff .d/3D + 5 em eners should not be less than'd/3D + 10 em :~r stiffeners on both sides; or .

where d is tho web heiqht ,rstiffeners on one side only~ In Cii1. '

.........

Gradeof Steel

tw >t ~ 40 mm 40 mm < t ~ 100 mm

St 37 d/206St44

d/218d/191

St 52d/20D

d/168 d/17S

7.7v- A part of the web equals to 25 times the web thickness and 12times the web thickness may be considered in the design of theintermediate and -theend stiffeners, respectively-

vi- Transverse stiffeners, bearing and/or intermediate should bedesigned as a column with a buckling length of 0.8d and meet therequirements of the compression elements given in Chapter 2.

vii- The connection between the transverse stiffener and the webshould be designed on the stiffener design force. For intermediatestiffeners, this connection is designed in such a way that thefasteners in either the upper or the lower thirds of the stiffeners

should transfer the design force.

7.4.2 Longitudinal Stiffeners

The moment of inertia of the longitudinal stiffener about the axisparallel to the web transverse direction should not be less than:

4 d(tw

)3 for longitudinal stiffeners provided at a distance of dIS to d/4

from the compression flange; andd(t

w)3for longitudinal stiffeners provided at the neutral axis of the

girder.

iv- Intermediate transverse stiffenforce C, equal to: ers should be designed to resist a

Plate Girders for Buildingsand Bridges

124 Plate Girders for Buildings 125and Bridges

..,

CHAPTER 8

Transverse Stiffeners

outstand I

I

-,-1outstand

TRUSS BRIDGES

8.1 GENERAL

For triangulated frames designed on the assumption of pinjointed connections, members meeting at a joint should, wherepracticable, have their centroidal axes meeting at a point; andwherever practicable the center of resistance of a connection shalllie on the line of action of load so as to avoid any moment due toeccentricity on the connection.

7.7 DEFLECTION

The allowable defiection of plate girders shallClause 9.1.3. be according to

Figure (7.1) Intermediate Transverse Stiffeners

7.5 SPLICES

8.2 SPACING AND DEPTH OF TRUSSES

Foot or pedestrian bridges shall be designed under the buildingrequirements as given in section9.2.

Where the design is based on non-intersecting members at ajoint, all stresses arising from the eccentricity of the members shallbe calculated and the stresses kept within the limits specified in

Clause 2.6.7.

The centroidal axes of the different chord sections shall bereplaced with an average axis for the whole chord.

The spacing between centers of main trusses should be sufficientto resist overtuming with the specified wind pressure and loadingconditions, otherwise provision must be specially made to preventsuch overtuming. In no case, shall this width be less than 1120 of theeffective span, not less than 1/3 of the depth. The depth of trussesshall be chosen such that the elastic deflection due to live loadwithout dynamic effect shall not exceed the values specified in

Clause 9.1.3.

Intermediate StiffenersEnd Stiffeners

7.6 UNSUPPORTED LENGTH OF COMPRESSION FLANGE

The unsupported length f .shall be according to Clause ~.3c:mpresslon fiange of plate girders

For simply supported parallel chord trusses, the depth shall·preferably be not less than 1/8 of the span for railway bridges or 1/10of the span for roadway bridges.

Plate Girders for Buildingsand Bridges

126 Tross Bridges 127

8.3 MINIMUM THICKNESS

The thickness of elements shall sal' fyof non-compact elements as given in T:ble ~. ~east the requirements

The minimum thickness of t Iaccording to Clause 9.1.4. gusse pates and other plates shall be

The critical sections of the gu t iresist safely the forces transmittedst"eth

Pates should be checked tomembers. a e gusset plates from the web

8.4 COMPRESSION MEMBERS

8.4.1 Slenderness Ratios

The maximum slender I'be according to Clause 4.;~ss ra 'as of compression members shall

8.4.2 Effective Buckling Length (KI)

be ia~:~~~~v;a~~~~i~~ ~~~1~~i~~~ ~f a compression.membermayanaiysis of the truss. rom an elastic critlcal buckling

8.4.3 Unbraced Compression Chords

~~~~:;£~a::?!~~e~~~~~ea~dt~~s:r~s;~;;~e~h~~~~~thn~a~~t:~~shall be taken adcOrdi~9r~~~~~:~~ 1h:.;~ect,ve buckling length (KI)

8.4.3.2 For a bridge where the .restrained by U-frames composed ~ompresslOn chord is laterallyto the verticals of the truss, the ~ff~~t~~eg,~ers ngldly connectedcompression chord (KI) shall be rdl uckhng length of thede . f acco 109 to Clause 4 3 23Th

sign a such U-frames will be according to CI 9 .... eause .3.2.3.

8.4.3.3 For continuous bridges, the effective buckling length of thecompression chord (KI) shall be determined from an elastic critical

analysis of the truss.8.4.4 Depth of Compression Chord Members

Compression chord members shall have a depth in plane of thetruss of 1/12 -1/15 of the panel length. The maximum depth may be1110 of the panel length; if this value is exceeded, secondarystresseswill have to be considered in the design. The recommendedwidth shall be 0.75 - 1,25 times the depth.

8.4.5 Depth of compression Web Members

For inclined compression web members the minimum depth inplane of the truss shall be determined to satisfy the buckling andslenderness ratio requirements. The depth may not be more than1115 of the unsupported length for these members; if this value isexceeded, secondary stresses will have to be considered in the

design.

8.5 TENSION MEMBERS

8.5.1 Slenderness Ratios

The maximum slenderness ratios of tension members shall

be according to Clause 4.2.2.

8.5.2 Effective Area

The properties of the cross section shall be computed from theeffective net sectional area, if bolls are used at splices orconnections of the member to other members. Effective net areashall be according to Clause 2.7.1.

8.5.3 Depth of Tension Members

For ncnzontat and inclined tension members the depth in planeof the truss shall not be less than 1130 of the unsupported length ofthese members in railway bridges and 1/35 of the said length inroadway bridges. The depth shall preferably not be more than 1/10

Truss Bridges 128 Truss Bridges 129

of the unsupported Iunsupported length f ength for chordor web members.

members or 1/15 of theCHAPTER 9

Ordinary grade steel and high tensile steel may be used joinly ina structure or in any member of a structure provided that themaximum stress in each element does not exceed the eppropriate

permissible stress.

9.1.2 Combined USe of Mild Steel and High Tensile Steel

(Hybrid sections) .

9.1.1.4 If connected on one side of a gusset plate, the effectivearea of sections in tension shall be taken as given in Clause 9.2.2.3 .

COMPLEMENTARY REQUIREMENTS FORDESIGN AND CONSTRUCTiON

9.1.1.1 All sections shall, as far as possible, be symmetrical aboutthe central plane of girder or truss. Web members shall preferably

have two planes of symmetry.

9.1.1.2 All welded, bOiled, riveted, or pinned connections should besymmetrically arranged so as to avoid eccentricity as far as

possible.

9.1.1.3 Members meeting at a joint should, as a rule, have their

center of gravllY lines intersecting at a point.

9.1.1 Symmetry and concentricity of Sections

The following Clauses shall apply equally to bUildings and

bridges.

9.1 GENERAL FOR BUILDINGS AND BRIDGES

8.6 LACING BARS, BATTEN PLATES AND DIAPHRAGMS

In double gusset s ctlmember shall b e Ions of a truss the two cand diaPhragmSe ~~:n~ct~ together by lacingo::~n~~parts of aChapter 9. e ails of such elements ' en platesare presented in

8.7 SPLICES AND CONNECTIONS

Splices in compression or .the maximum strength-of the ~;~~n members shall be designed 0er. . n

Except as otherwise .shall be designed for a prov~ded, connections for mainof the actual force in th~paClty based on not less than th members

~v~~~~~ I~~:~~~~ ~~ ~1~~~~~e~t~et~~i~~~e~~~~ct~~~_~~n~~~:e maximum strength in the n anymember.

Truss Bridges 130

Where L IS the span.

Lacing bars shall be connected such that there will be noappreciable interruption of the triangulation of the system.

Lacing bars shall be inclined at an angle of 50° to 70° to the axisof the member where a single intersection system is used and at anangle of 40° to 50° where a double intersection system is used.

As far as practicable, the lacing system shall not be variedthroughout the length of the compression member.

9.1.5.1 Lacing of Compression Members

The maximum unsupported length of the compression memberbetween lacing bars (l,) whether connected by welding, bolting orriveting, shall be such that the slenderness ratio of each component

9.1.5 Lacing Bars, Batten Plates and Diaphragms

An addition shall be made to the sectional areas required to resistthe computed stress, so as to allow for corrosion, when climateinfluences or other conditions may set up such a corrosion or whenthe steelwork is not accessible for painting on both sides. In suchcases the minimum thickness as given above shall be increased byat ieast 1 10m.

The minimum thickness (ln 10m) to be used in structuralsteelwork (except cold-formed steel sections) shall be as given inthe foliowing Table.

9.1.4 Minimum Thickness of Plates

Sections Railway Roadway BuildingsBridges Bridges

-Plates 8 8 5

-Gusset plates for 12 10 8

maintrusses

9.1.3 Deflection of Beams Portal FramI es and Trusses

The calculated deflection d .effect of any beam or trus ue to live load only without dynamicshown in Table 9.1. The def~e~~:~' s~~~ be greater than the valuestmparr the strength or efficiency of th ~ not, however, be such as tothe finishings. e s ructure or lead to damage to

Table (9.1) Maximum Deflection in Build' .lOgs and BndgesMember

Beams and trusses in buildingsMax. Deflection

plaster or other brittle finishcarrying U300

All other beamsCantilevers U200

HOri~ontal deflection at tops of columns inU180

~:~~:~storey bUildings other than portalHeight 1300

~~;~~~~tai't~eflection in each storey of a Height of storey under. WI more than one storevHorlzontat deflection at the to conSideration 1 300

buildmo With more than one storev p of a Total height of bUiiding

~orlzontal deflection at tops of colum .1500

ort.al frames without oantrv cranes ns In Heightl150

HOrizontal deflection at tops of col . Toportal frames with gantry cranes umns In be decidedaccording to therecommendations ofthe gantry cranemanufacturer, butshould not exceed the

Crane track oirders heioht 1150

Railwav bricoes U800

Roadwav'bndces U800

Overhanoino portions of bridoesU600U300

Complementary Requirementsfor OeSJgn and Construction

132 Complementary Requirementsfor Designand Construction 133

part between consecutive connections (t,/r,) shall not be more than50 in bridges and 60 in buildings or 2/3 times the slenderness ratioof the member as a whole about the x-x axis, whichever is thelesser.

. . hall be capable of carrying theBatten plates and the" fastenings sdesigned (considered as 2%

forces for which the lacing system I~ ,

of the force in the member under design ).

Bolten

r-, Botten Plate

. .'"' lacin9 bars: e ,, , ,

"}.\ lz,<, , ,,

lntarmidlole

-~ Plale

-(-l-tX __ -I x-\-z

y

lo~in9 bor~

_uf-=("r,x~_+_.:....x

, ' zl..-l-f

y

Figure (9.1) Laced Compression Members

The required section of lacing bars shall be determined by usingthe permissible stresses for compression and tension membersgiven in Chapter 2 .

ii- In welded connections: the distance between the inner ends ofeffective lengths of welds connecting the bars to the components insingle intersection lacings, and 0.7 of the length for doubleintersection lacinq effectively connected at the intersection.

i- in bolted or riveted connections: the length between the inner endbolts or rivets of the lacing bar in single intersection iacing and 0.7 ofthis length for doubie intersection lacing effectively connected at theintersection.

The ratio (Wr) of the lacing bars shall not exceed 140. For thispurpose the effective length (kl) shall be taken as follows:

Laced compression members shall be provided with batten platesat the ends of the lacing system, at points where the lacing system isinterrupted, and where the member is connected to anothermember.

The length of end batten plates measured between endfastenings along the longitudinal axis of the member shall be notless than the perpendicular distance between the centroids of themain components, and the length of intermediate batten plates shallnot be less than 3/4 of this distance, see Figure 9.1.

The thickness of the plates shall not be less than 1/50 of thedistance between the innenmost lines of welds, bolts or rivets.

Complementary Requirementsfor Design and Construcrion 134

9.1.5.2 Battening of Compression Members

s racticable, be spaced andThe battens shall, as far a T~ number of battens shall be

proportioned unifonmly throughout. e

Complementary Requifen:ents 135for Design and Construction

'~\I,

such that the member is divided into not less than three bays withinits actual center to center of connections. Battens may be plates,channels or othersections.

Battened compression members not complying .with theserequirements, or those subjected to bending moments In the planeof the battens, shall be designed according to the exact theory ofelastic stability.

a.d/a

rlr....::a / 2 t-01 2

Bolted

l'_L~zx j-H-xT

, y z

a.dl a

d

all

Welded

111--11 Id

-l11-----11 r

1z

J_~Zx j-H- x

T, y Z

1*·'. ' 1*"

1zT 1~l. 143/ 4•

.1143/4.

Intermediate Batten

The effective length for each component of the main memberbetween two consecutive battens parailel to the axis of the membershail be taken as the iongitudinal distance between the endfasteners, (l,). End battens shall have an effective length of not lessthan the perpendicular distance between the centroids of the maincomponents, and intermediate battens shail have an effective lengthof not less than 3/4 of this distance, but in no case shail the length ofany batten be less than twice the width of the smaller component inthe plane of the battens, see Fig. 9.2.

Where:d = The longitudinal distance center to center of battens.a ::; The minimum transverse distance between the centroids

of welding, bait groups, or rivets.o = The transverse shear force ( considered as 2% of the

force in the member under design ).n = The number of parailel planes of battens.

The member as a whole can be considered as a vierendeel _girder, or intermediate hinges may be assumed at mid distances tochange the system into a statically determinate system. Battens andtheir connections shail be designed to resist simultaneously alongitudinal shear force = (O.d I n.a) and a moment = (O.d I 2n) asshown in Fig. 9.2.

In battened compression members, the slenderness ratio l,/r, ofthe main component shail not be greater than 50 in bridges and 60in buildings or 2/3 times the maximum slenderness ratio of thememberas a whole, whichever is the lesser.

The thickness of batten plates shail be not less than 1/50 of theminimum distance between the innermost lines of connecting welds,bolts, or rivets.

Figure (9.2) Battened Compression Members

Complementary Requirementsfor Designand Construction 136

Complementary RequirementsforDesign andConstruction 137

In double gusset plane trusses, the two component parts oftension members shall be connected together by diaphragms as wellas lacing bars or batten plates simiiar to those of the compressionmembers, but their thicknesses may be reduced by 25 %.

9.1.5.5 Lacing or Battening of Tension Members

Diaphragms are transverse plates or channels connected to thetwo webs of the box section. They are necessary to ensure therectangular shape of the box section. In the chords, at least onediaphragm between the two panel points of the member is to beprovided. In the diagonals, at least one diaphragm near each end isalso to be provided.

In addition to the diaphragms required for the proper functioningof the structure, diaphragms shall be provided as necessary forfabrication. transportation and erection.

9.1.5.4 Diaphragms in Members

9.1

Latticed

1(' J2 (. J2V r; + ~:

9.1.5.3 Equivalent Slenderness Ratio of Battened orCompression Members

For battened or latticed compression members the slenderatio (k€) shall be modified as given below: ' mess

a- For buckling in plane (y-y) Figure 9.2, the permissible stress for~embers shall be obtained by using the slenderness ratios and theormulae for solid members given in Chapter 2.

b For b kr .- uc Ing 10 the plane (x-x), the slenderness ratio (€ /r) inthese formulae shall be replaced by the values given hereund~r.'

i. For members with lacing bars and batten plates at their ends:

139Complementary ReqUirementsfor Design and Construction

b. Structural buildings may also be provided with an erectioncamber, as indicated in the project specifications or the plans.

a. Main girders of bridges more ·than 15 m in length of truss or plategirder construction shall be provided with such a camber that, underthe effect of the dead load and haif the iive load (without dynamiceffect), the said camber shall be taken out by the deftection. Rolledbeams and plate girders 15 m or iess in length, need not to becambered.

d. Camber may be required to maintain clearance under allconditions oi loading, or it may be required on account ofappearance. Camber may also result from prestressing.

c. Camber diagrams and fabrication details shall be shown on theproject drawings and fabrication details.

9.1.6 Camber

9.2

138

Where:€z = Unsupported length of each separate part as defined

before.

rz : Radius of gyration for one part for the axis (z-z).

e- Members connected in both directions by lacing bars or battenil~es shall be desiqned similarly by calculating the value indicatedn quations s.j and 9.2 for the axis (x-x) or (y-y) giving the smallest

moment of mertia for the total section and (rz) for the axis (z-z)giving the least moment of inertia for one separate part.

Complementary Reauirementsfor Design and ConsfrucDon

9.2 STEEL BUILDINGS

9.2.1 Depth - Span Ratios

The depth of rolled beams in floors shall preferably be not lessthan 1124 of their span. Where floors are subject to shocks orvibrations, the depth of beams and girders shall preferably be notless than 1120 of their span. The depth of simply supported roofpurlins shall preferably be not less than 1140 of their span. Beams,girders and trusses supporting plastered ceilings and all other beamsshall be so proportioned that the maximum deflection due to liveioad without dynamic effect shall not exceed the values in Clause9.1.3.

9.2.2 Trusses

Provisions for bridge trusses Chapter 8 shall apply except asotherwise prescribed herein.

9.2.2.1 General

The gross sectional area shall be taken as the area of cross­section as calculated from the specified size.

The net sectional area shall be taken as the gross sectional arealess deductions for bolt holes, rivet holes and open holes, or otherdeductions specified herein.

In taking deductions for bolt and rivets holes, refer to Clause6.2.2 for details about the excess to the nominal diameter of the boltor nvet that should be deducted.

For calculation of the effective net sectional area. refer toClause 2.7.1.

9.2.2.2 Compression Members

In case of compression members unsymmetrically connected tothe gusset plate, the effect of eccentricity must be taken intoaccount, see Clause 2.6.4.

9.2.2.3 Tension Members

a. Tension members should preferably be of rigid cross sections,and when composed of two or more components these shall beconnected by batten plates or lacing bars.

For horizontal and inclined members, the depth shall be not lessthan 1160 of the unsupported length of these members.

b. The properties of the cross section shall be computed from theeffective sectional area.

When plates are provided solely for the purposes of lacing orbattening, they shall be ignored in computing the radius of gyrationof the section.

c. The effective sectional area of the member shall be the grosssectional area with the following deduction as appropriate:

i-Deductions for bolt and rivet holes; Chapter 2.ii- Deductions for members unsymmetrically connected to thegusset plates.

9.2.2.3.1 Effective Area of Unsymmetrical Simple TensionMembers

i- Single Angles, Channels and T-sections

For single angle sections connected through one leg only, singlechannel sections connected only through the web, and T-sectionsconnected only through the flange, the effective area should betaken as the net area of the conneced leg, plus the area of theunconnected leg multiplied by:

Complementary ReqUirementsfor Designand Construction 140

Complementary RequirementsforDesign andConstruction 141

.................................................

Gusset 7

A,")

Gusset 7

2. Connected by bolts or welding such that the slenderness ratio ofthe individual components does not exceed 80,

A,

L9.3

//

Gusset

3A,

./ 7

Gusset

A,

-~

/Gusset / Gusset 7

Figure (9.4) Double Angles Connected to Gusset Plates

then the effective area may be taken as the net area of theconnected legs plus the area of the outstanding legs multiplied by :

9.4

Where lug angles are used in the connection of single angle thenet area of the whole member shall be taken as effective.

The connections at ends of tension or compression members intrusses shall be designed on the actual forces in the members.

The full splices of members of the section shall be designed onthe maximum strength.

9.2.2.4 Connections and Splices

Where:A, = Net area of connected leg.A2 = Area of unconnected leg.

Figure (9.3) Single Angles, Channels and T-SectionsConnected to Gusset Plates

Where:A, =A2 =

Net area of connected leg.Area of unconnected leg.

Forback to back double angles connected to one side of a gussetor section, the angles may be designed individually as given above.

ii- Double Angles9.2.3 Columns and Column Bases

142

Proper provision shall be made to transfer the column loads andmoments, if any, to the foundations.For back to back double angles connected to one side of a gusset

or section which are:1. !n contact or separated by a distance not exceeding the thicknessof the parts with solid packing pieces, or

Complementary Requirementsfor Designand Construction

CompiementslY RequirementsforDesignand Construction 143

When the end of the column shafl and the base components arenot planed flush, the fasteners connecting them to the base plateshall be sufficient to transmit the forces to which the base issubjected.

Where the end of the column shaft and the base components areplaned flush for bearing, not less than 60 % of the transferable loadshall be considered as taken by the fasteners.

9.2.4 Bracing Systems

When floors, roofs, or walls are incapable of transmittinghorizontal forces to the foundations, the said forces shall betransmitted to the foundation through the steel framework.Triangulated bracing andlor portal construction shall be provided tothat purpose.

In bUildings where high speed travelling cranes are supported bythe structure or where a bUilding may be otherwise SUbject tovibrations or sway, additional bracing shall be provided to reduce thevibrations or sway to a suitable minimum. Bracing systems have tobe provided to support compression members against bucklingoutside the plane of the frame and to reduce the slenderness ratio oftension chord members.

9.3 STEEL BRIDGES

9.3.1 Bridge Floors

9.3.1.1 Types

Floors of railway bridges may be of the open timber floor type,the ballasted floor type, or the steel plate type with rails directlyseated on the steel plate.

Floors of roadway bridges may be constructed of reinforcedconcrete slab type, the steel plates type or the orthotropic plate type.

9.3.1.2 Floor beams

9.3.1,2.1 General 'ffFloor beams shall be designed with special reference.to sti ness

by making them as deep as economy or the limiting under clearancewill permit.

In the case of rolled steel sections the depth of stringers shallpreferably be not less than 1/12 of their span. However, thedeflection of such stringers should satisfy the deflectionrequirements asqlven in Clause 9.1.3.

The depth of cross girders shall preferably be not I~ss than 1110of their span. However, the deflection of s~ch cross girders shouldsatisfy the deflection requirements as gIven In Clause 9.1.3.

In the calculation of. continuous stringers, unless otherwiseobtained by a structural analysis, the following bending momentsmay be assumed: . . M

Positlve moment In end span 0.9 aPositive moment in intermediate spans 0.8 MoNegative moment at support 0.75 Mo

where M is the maximum bending moment for a simplysupported st~nger. The same value of bending moment. shall beassumed for stringers fitted between cross girders and provided Withtop and bottom plates resisting the full negative moment at thesupport. In all other cases, stringers shall be calculated as Simplysupported beams.

In railway bridges, the ends of deck plate girders and stringers atabutments of skew bridges shall be square to the track, unless aballasted floor is used.

9.3.1.2.2 Cross Girders

Cross girders shall preferably be at right ang.les to the maingirders and shall be rigidly connected thereto. Sidewalk brackets

Complementary Requirementsfor Design and Construction 144 Complementary Requirements

for Design and Construction 145

shall be connected in such a way that the bending stresses will betransferred directly to the cross girders.

Cross girders over the supports shall be designed to permit theuse of jacks for lifting the super structure. For this case thepermissible stresses may be increased by 25 %( see also Clau;e 2.5- erection stresses).

9.3:2 Bridge Bracings

9.3.2.1 Lateral Bracings

In all bridges rigid lateral bracing shall extend from end to endand be capable of transmitting, to the bearings of the bridge, th~honzontal forces due to wind pressure, or earthquake load, lateralshock, or centrifugal and braking forces.

Whenever possible, two systems of lateral bracing may be usedexcept in the case of deck spans less than 15 m long, the lowerlateral bracing may be omitted. Solid floors may replace the bracingsystem in its plane.

If the bracing is a double web system and if its members meetthe requirement for both tension and compression members, bothsystems may be considered acting simultaneously. It may beassumed as an approximate solution that both systems equallyshare the lateral forces. In such case, a further reduction for 20% inthe allowable stresses (of bracing members) prescribed in Clause2.3 shall be made in order to account for that approximation.

The depth of the compression bracing members shall be not lessthan 1/40 of their unsupported length.

In through bridges these portals shall generally be closed framesconsisting of the cross girders, the two end posts and an uppergirder as deep as possible. In deck bridges end cross frames areused and shall be of the rigid type, either crossed diagonals orWarren type.

In all railway and in road deck bridges there shall be at least twointermediate transverse bracings to increase the stiffness of thebridge. These intermediate transverse bracings are made lighter, incross section, than the end transverse bracings. Although theintermediate cross frames will release the end cross frames frompart of the horizontal reaction of the upper wind bracing, yet it isrecommended not to consider that release unless the bridge istreated as a space structure.

9.3.2.3 Lateral Support at Top Chords or Flanges of ThroughBridges (Pony Bridges)

In truss bridges without upper lateral bracing and in plate girderpony bridges, the upper chords or flanges shall be laterallyelastically supported by an open U-frame consisting of the crossgirder and the two posts or stiffeners rigidly connected to each otherby bracket plates as large as the specified clearance will allow.These open U-frames shall be designed to resist a horizontalforce equal to 1/100 of the maximum compressive force in the chordacting normal to the compression flange of the girder at the ievel ofthe centroid of these flanges. Generally, the U-frames are providedat every panel point or every second panel point.

9.3.2.4 Stringer Bracing and Braking Force Bracing Systems

146

To avoid lateral bending of stringers and cross girders in railwaybridges, bracing systems shall be provided to resist the lateral shockeffect and the braking forces. These bracing systems may beomitted in case of solid floors. The stringer bracing shall be providedas near as possible to the upper flanges of the stringers to supportthese compression flanges against lateral buckling.

9.3.2.2 Portal Bracing and Intermediate Transverse Bracing

In through bridges having upper and lower lateral bracings thereshall be provided at each end a portal frame capable of trans';'ittingto the beanngs, the horizontal reactions of the upper lateral bracing.

Compfemenlary RequirementsforDesignand Construction

Complementary ReqUirementsfor Design and Construction 147

Intermediate cross-frames or inverted U-frames may be providedbetween stringers of long spans to increase lateral stability due totorsion.

The braking force bracing system may be arranged at each crossgirder. In general two braking force bracing systems at the quarterpoints of each span are sufficient.

9.3.2.5 Additional Shear for Lateral Bracing

The lateral bracing between compression chords and end postsof trusses and between compression flanges of plate girders shall bedesigned to resist, in addition to the effect of wind and other appliedforces, a cross shear at any 'section equals to two per cent of thesum of the compression forces at the point considered in themembers connected.

9.3.3 Expansion - Bridge Bearings

9.3,3.1 The design of bridges shall be such as to allow for thechanges in length of the span, resulting from changes intemperature, live load stresses and small displacements of piers orabutments. A play of at least ± one em per 10m length shall beprovided to that effect.

End-bearings shall be so designed as to permit deflection of themain girders without unduly loading the edges of the bearing platesand the face of the abutment or pier.

9.3.3.2 Bearings of bridges of more than 15 m span shall beprovided with rollers at the expansion end, except when the spanrests on structural steel parts. In this case the structure may bearranged to slide on bearings with smooth curved surfaces, providedthe frictional forces are duly accounted for.

Expansion rollers shall be not less than 12 em in diameter, andthe number of rollers shall be either 1, 2, 4, or 6. Rollers withtruncated sides (rockers) may be used in special cases only.

All bearings shall be so arranged that they can be readilycleaned.

Rollers shall be"coupled together by means of strong side barsand provided with ribs, grooves or flanges so as to ensure theirprescribed longitudinal movement and prevent any lateraldisplacement.

The lower bearing plates shall rest on a 2 to 3 em thick layer ofgrout or on a 3 mm sheet of lead and shall be provided withmasonry ribs capable of transmitting the horizontal components ofthe bridge reaction. .

9.3.3.3 Modern bearings can be also constructed from newdeveloped materials such as Polytetra Flouroethylene PTFE, knownas Teflon and Synthetic Rubber, known as Neoprene. The designwill be according to the specifications of the producer.

9.3.4 Track on Railway Bridges

The fixation of sleepers and rails to the stringers of railwaybridges with open floors, shall preferably be as shown in Fig. 9.5.Rail joints shall be avoided, if practicable, or they should be welded.

For standard-gauge, (1.435mm) tracks, the weight of the rails,guard rails, fish plates and bolts, saddle plates, coach screws,attach-plates to sleepers, etc.., shall be taken equal to 250 kglm oftrack, unless otherwise specified.

The height of rail shall be measured as 15 em unless otherwisespecified.

The sleepers, preferably of oak or American pitch pine, shall benot less than 260 em long and spaced at not more than 50 em.Timber sleepers shall be designed on the assumption that themaximum wheel load on a rail is uniformly distributed over twosleepers, and is applied without dynamic effect. Laying of

Complementary Requirementsfor Design and Construction 148 Complementary Requirements

for Design and Construction 149

Slringar

1.50 m

~Ck2.6& m

II

Iflo! 250,7010

1.50 m

T

elastomeric pads between the rails and the sleepers shall beprovided for better absorption of impact effects. In ballasted floors,the rails must be levelled and the minimum thickness of ballastunder the sleepers should not be less than 20 em.

The alignment of curved tracks must be perfect. When leveldifferences in the rails are corrected by adding wooden wedges. theypresent often large ply that must be eliminated. Full sloped woodensleepers with suitable super elevation must be used.

'IHole 22 mm lcmtor boll 20 mm D.

Figure (9.5) Fixation of Sleepers on Steel Bridges

Complemenfary Requirementsfor Designand Construction 150

Complementary RequirementsforDesign and Construction 151

CHAPTER 10

COMPOSITE STEEl- CONCRETE CONSTRUCTION

This Chapter applies to steel beams supporting concrete slabsthat are interconnected such that they act together to resist bending.Provisions included herein apply to simple and continuouscomposite beams constructed with or without temporary shoring.Composite beams must be provided with shear connectors, or elsecompletely encased in concrete.

This Chapter also applies to column and beam-column compositemembers composed of rolled or built-up structural steel shapesencased in concrete or tubing filled with concrete.

10.1 COMPOSITE BEAMS

10.1.1 Scope

This section deals with simply supported and continuous beamsused in buildinqs and roadway bridges. It is related to beamscomposed of either rolled or buiit-up steel sections, with or withoutconcrete encasement acting in conjunction with an in-situ reinforcedconcrete slab. The two elements are connected so as to fonm acomposite section acting as one unit. Figure 10.1 shows somecommon cross-sections of composite beams.

10.1.2 Components of Composite Beams

10.1.2.1 Steel Beam

All steel parts used in the composite beams shall comply withtheir relevant specifications. The steel beam may be a rolledsection, a rolled section with a cover plate attached to the tensionflange, a plate girder, or a iattice girder. Composite construction ismore economic when the tension flange of the steel section is largerthan the compression flange. The compression flange of the steel

beam and its connection to the web must be designed for the shearflow calculated for the composite section.

Figure (10.1) Common Cross-Sections of Composite Beams

During construction, the compression flange must satisfy localbuckling and lateral torsional buckling requirements as per Clause2.6.1 and Clause 2.6.5.2, respectively. After construction, however,the composite section shall be exempt from such requirements.

10.1.2.2 Concrete Slab

The concrete used for composite construction shall comply withthe current Egyptian Code of Practice for the Design of ReinforcedConcrete Structures. The minimum accepted value for thecharacteristic cube concrete strength, f"" is 250 kg/em' for bUildingsand 300 kg/em' for bridges. For deck slabs subjected directly totraffic (without wearing surface), the value of f", shall not be lessthan 400 kg/em'.

The slab may rest directly on the steel beam or on a concretehaunch to increase the moment of inertia of the composite section. Itis also possible to use a fonmed steel deck with the deck ribsoriented parallel or perpendicular to the steel beam. The concreteslab may also be prestressed.

10.1.2.3 Shear Connectors

Composite Steel-ConcreteConstruction 152 Since the bond strength between the concrete slab and the steel

Composite Steel-Concrete 153Construction

beam is not dependable, mechanical shear connectors must beprovided.

They are fastened to the top flange of the steel beam andembedded in the concrete slab to transmit the longitudinal shear andprevent any slippage between the concrete slab and the steel beam.Furthermore, they prevent slab uplift.

10,1.4.1 Span to Depth Ratio

The ratio of the beam span, L, to the' beam overall depthincluding concrete slab, h, lies generally between 16 and 22. Forlimited girder depth, Uh may exceed 22 provided that the deflectioncheck as per Clause 10.1.4.7 is satisfied.

There are several types of the shear connectors such as:anchors, hoops, block connectors (including: bar, T-section, channelsection, and horseshoe), studs, channels, and angle connectors aswill be discussed in details in Clause 10.1.7.

10.1.3 Methods of Construction

Two different methods of construction are to be considered:

~~do

}

10.1.3.1 Without Shoring (Case I)

When no intermediate shoring is used under the steel beams orthe concrete slab during casting and setting of the concrete slab, thesteel section alone supports the dead and construction loads. Thecomposite section supports the live loads and the superimposeddead loads (flooring, walls, etc.) after the slab has reached 75% ofits required characteristic strength, f".

10.1.3.2 With Shoring (Case II)

s-s Centrol axis of steel section.e-r-e Centrol oxis of concrete slob (neglecting haunch).v-v Central axis of composite section.

Figure (10.2) Section Dimensions and Notations

10.1.4.2 Thickness of Concrete Slab

• For Buildings

10.1.4 Design of Cornposite Beams

Design of composite beams is based on the transformed sectionconcept. Both steel and concrete are considered to be acting as oneunit.

When an effective intermediate shoring system is utilized duringcasting and setting of the concrete slab, the composite sectionsupports both the dead and live loads. Shoring shall not be removeduntil the concrete has attained 75% of its required characteristicstrength, f,".

Compos;te Steet-ConcreteConstruction

154

The minimum concrete slab thickness is as follows:* For roof slabs t ~ 8.0 cm* For repeated floors t ~ 10.0 cm* For fioors supporting moving loads (e.g., garages) t ~ 12.0 cm

Slabs can be provided with haunches inclined wtth a slope notsteeper than 1:3 (tan B ,; 3, Fig. 10.3). The height of the haunchproper, dh, is normally chosen not more.than one and a half timesthe slab thickness, t. In addition, the total depth, h, of the compositesection is normally chosen not greater than two and a half times thedepth of the steel beam, h,.Composite SteeJ..Concrete 155Construction

• For Roadway Bridges:

t .0

The thickness of the deck slab shall not be less than 16 em. If theslab is subjected directly to traffic with no wearing surface, theminimum thickness shall be 20 ern. z10.1.4.3 Effective Width of Concrete Slab

a- For Buildings tThe effective width 2b., Fig. 10.4, shall be taken the least of: ...0 '"C..

1- (U4). ;;; CIl i:i:2- Spacing between girders from center to center. ..

tss:

3- 12ts1ab + bnange. '" u e~

~c U-'0 ::l C

TIn..

where L is the actual span between the supports. :I: 0.. 00 .0 OSCIl

Where adjacent spans in a continuous beam are unequal, the '" c s:0 -value of b. to be used for calculating bending stress and longitudinal -e- 'tI

v/ 'iii

t 3:shears in the regions of negative bending moments shall be the c., .,mean of the values obtained for each span separately. E >

C :;:;u

" ;:; .0 ~b- For Bridges0 w:::. ::t

The effective width b. of the concrete flange on each side of the e

t0

center line of the steel beam shall be taken as the actual width b for ~ ::l :::.'"values of b not exceeding U20 of the span of the beam where b is "1 L! e

'" ::leither half the distance from the center line of the beam to the VI '"s: .0 L!center line of the adjacent beam or the distance from the center lineof the beam to the edge of the slab where there is no adjacentbeam, Fig. 10.4.

t .0

In cases where b" is different from bj, then the effective widthb., will be different from b.,.

.0

Composite Sfeel-ConcreteConstruction 156 Composite Steel·Concrete

Construction 157

For values of b greater than U20 of the span, the effective widthon each side of the center line of the steel beam shall be calculatedfrom the formula:

..•.................• , ...., .••.........••......

But shall not be taken less than U20.

10,1 T=j;~~f'll -r!tJ-- 1$

O,L, + (D.L,+L.L) • (D.L, +O.I.,+L.L)

(a) Without Shoring (Case I)

10.1.4.4 Calculation of Stresses

According to the working stress design method, the compositebeam shall be transformed to an equivatent virtual section using themodular ratio, n. The value of n=E,/Ee may be taken as the nearestwhole number (but .not less than 7). Table 10.1 lists therecommended values of n for some grades of concrete.

Table (10.1) Recommended Values of the Modular Ratio (n)

Concrete Modulus ofCharacteristic Elasticity of

Modular Ratio, nCube Strength, Concrete, Ecfeu (kg/cm2

) (tlcm2)

250 220 10300 240 9400 280 8

;" 500 310 7

Bending stresses in the composite section (steel beam, concreteslab, and longitudinal reinforcement) shall be calculated inaccordance with the elastic theory, ignoring concrete in tension andassuming no slippage between the steel beam and concrete slab.Figure 10.5 illustrates the distribution of bending stresses forcomposite beams constructed with or without shoring.

(a) With Shoring (Case II)

D·l. t =D.od Loods, D.L'2= Super Imposed Oead LoadlL.L. = live Loads

Figure (10.5) Stress Distribution

Maximum bending stresses in the steel section shall comply withClause 2.6 except that the compression flange connected to thereinforced concrete slab shall be exempt from local and lateralbuckling requirements. Whereas maximum bending stresses in theconcrete slab shall not exceed the allowable limits permitted by theEgyptian Code of Practice for the Design of Reinforced ConcreteStructures. .

The steel web alone shall resist the vertical shear stresses of thecomposite beam, neglectingany concrete slab contribution.

10.1.4.5 Stress in Concrete Slab

The design of the concrete slab shall be carried out according tothe latest edition of the Egyptian Code of Practice for the Design of

Composite Steel-ConcreteConsrruction 156 Composite Steel-Concrete

Construction 159

""'"

Reinforced Concrete Structures. If the section is in the positivemoment zone, and where the neutral axis falls inside the concreteslab, the tensile stresses thus created in the concrete must notexceed the values listed in Table 10.2.

Table (10.21 Allowable Tensile Stress for ConcreteConcrete Characteristic

250 300Cube Strength, f,", kg/em' 400 ;, 500

Tensile Stress, kg/em' 17 19 23 27

10.1.4.6 Continuous Beams

The composite construction of continuous beams makes itpossible to further reduce the depth and dellection of the beams.Three methods may be adopted to design the section of thecontinuous beam at intermediate supports (i.e., zones of negativebending moments):

a- Steel section alone may be designed to support all loads, deadand iive.

The neutral axis is to be calculated from the following formula ifthe cooperation of concrete in tension is neglected (Fig. 10.6).

If the tensile stress in concrete exceeds the above limits, crackswill initiate and the concrete in this zone shall not be considered inthe calculation of the composite section inertia.

If in the zone of positive moment, the neutral axis falls inside theconcrete slab, the tensile stresses thus created in the concrete mustnot exceed the maximum allowable stress of the used concreteotherwise the longitudinal shear stresses will not be efficientlytransmitted to the dowels: c- Composite section may be designed to support all loads, dead

and live, provided that tensiie stresses in the concrete slab shallnot exceed values listed in Table 10.2.

b- Steel refnforcement within the concrete slab effective widthand extending parallel to the beam span, with an adequateanchorage length in accordance with the provisions of theEgyptian Code of Practice for the Design of Reinforced ConcreteStructures, may be used as a supplementary part of the steelsection. In such a case, shear connectors must be extendedabove supports.

In the negative moment regions, the lower lIange of the steelbeam shall be checked against lateral and local buckling provisionsaccording to Clause 2.6.5.5. The point of contraflexure maygenerally be treated as a brace point.

10.21+ 2bEys -1)

nA s

Figure (10.6) Calculation of the Neutral Axis

10.1.4.7 Deflections

If the construction is shored during construction. Case II, thecomposite section will support both the dead load and the live loaddeflections. However, if the construction is not shored, Case I, thetotal deflection will be the sum of the dead load deflection of thesteel beam and the live load deflection of the composite section.Deflection allowable limits shall follow the requirements of Clause9.1.3.

Composite Steel-ConcreteConstruction 160

Composite Steef.ConcrefeConstruction

161

10.1.4.8 Design for Creep and Shrinkage

If shoring provides support during the hardening of concrete, i.e.,Case II, the total deflection will be a function of the compositesection properties. Account must be taken of the fact that concrete isSUbject to creep under long-time loading (I.e., dead load) and thatshrinkage will occur. This inelastic behavior may be approximatedby multiplying the modular ratio, n, by a factor of two. The result is areduced moment of inertia for the composite section, which is usedin computing the dead load deflections and stresses. When the liveloads are expected to remain for extended periods of time, such asstorage structures and garages, the conservative approach is to usethe reduced composite moment of inertia (i.e., using 2n instead ofn).

For roadway bridges, one third of the concrete modulus ofelasticity, E,/3 instead of E, (I.e., using 3n instead of n) shall beused in computing sustained load creep deflections and stresses.

Besides minimizing grout loss du~ng :ng of n::tC:S\~b :~~closures enhance the shear connectIvity een costeel beams at zones of maximum shear forces. End closures alsohelp in resisting forces arising from shnnkage and creep.

teT ~~'51ct. (cd (b) (.)

(0) Uniform Temperature Change(b) Variable Temperature Change

(c) Variable Temperature Change

Figure (10.7) Temperature Distribution

If construction is without shoring, Case I, and live loads are not ofthe prolonged type, creep effect may be neglected.

10.1.4.9 Design for Temperature Effect

10.1.5 Concrete Slab Edges

Sleel beam

Concrete slab

163

End

End Closure

Sec. (A-A)

composite Steel-ConcreteConstruction

Figure (10.8) End Closure for Concrete Slab

10.1.6 Design of Encased Beams

A beam totally encased in concrete cast integrally wllh the slab,as shown in Fig. 10.9, may be assumed to be interconnected to.theconcrete by natural bond, without additional anchorage, provided

that:162

Composite Steel-ConcrefeConstruction

Concrete slab edges shall be provided with end ciosures, e.g.,channels, angles, or plates, as shown In Fig. 10.8. End closureshave to be fixed to the steel beams before casting the concrete slab.

The variation of temperature shall be assumed according to theEgyptian Code of Practice for Calculating Design Loads and Forceson Structures. In general, a 30°C uniform variation of the overalltemperature of the structure is assumed. Due consideration shall begiven for the fact that although the coefficient of thenmal expansionfor both steel and concrete is identical, the coefficient of thermalconductivity of concrete is only about 2% of that of steel. Thereforethe top of the concrete slab and other levels through the depth of thebeam shail be assumed as shown in Fig. 10.7c.

a- Concrete cover over the beam sides, top and bottom flange isat least 40 mm.

b- Top flange of the beam is at least 50 mm above the bottom ofthe slab.

C-, Con~rete encasement contains adequate mesh or otherrelnforclnq steel throughout the whole depth to prevent spallingof the concrete.

Prior to hardening of the concrete, the steel section alone mustbe proportioned to support all dead and construction loads accordingto Clause 2.6.5.

10.1.7 Shear Connectors

Except for totally encased beams. the horizontal flexural shearforce at the interface between the concrete slab and the steel beamshall be transferred by shear connectors, as shown in Fig. 10.10 toFig. 10.12, throughout simple spans and positive moment regions ofcontinuous beams. In negative moment regions, shear connectorsshall be provided when the reinforcing steel embedded in theconcrete is considered as part of the composite section or when theconcrete tensile stresses do not exceed allowable values listed inTable 10.2..

10.1.7.1 Horizontal Shear Force

After hardening of the concrete the completely encased steelbeam IS restramed from both local and lateral torsional buckling.Two alternatives can be used for the design in this case:

a- The composite section properties shall be used in calculatingbendrng stresses, neglectmg concrete in tension.

Shear connectors shall be designed to transfer the horizontalshear flow between the steel and concrete. The spacing between

-snear connectors, e the pitch, shall be determined such that theconnector shalt transfer the shear flow along the distance e.However, in buildings, in regions of positive moment, the averagespacing between shear connectors can be used.

Figure (10.9) Encased Beam

b- The steel beam alone is proportioned to resist the positivemoment produced by all loads, live and dead, using an allowablebending stress of 0.72 Fy , neglecting the composite action.

The longitudinal spacing of the connectors shall not be greaterthan 60 cm or three times the thickness of the slab, or four times theheight of the connector, including hoop if any, whichever is the ieast.

The minimum concrete cover above the top of the connectorshall not be less than 5 em.

10.1.7.1.1 Size and Spacing of Connectors

If the dead load stresses are carried by the steel section, shearconnectors may be designed to carry shearing forces due to liveloads only. However, to allow for the effects of shrinkage and creepand to give better security against slip, it is recommended to loadthe connectors by half the dead and the full live load shear stresses.

10.1.7.1.2 Design of Pitch of Connectors

I" .

:;"4Cmm~ l

~40mm

I ; I+ SOmm<

In~40mm +

=-: ~40mm

Composite Steel~Concrete

Construction 164 Composite Steel-ConcreteConstruction

165

Longitudinal shearing force per one em length of b. eam equals:

QAcyc/lv ." ".""." . .................... 10.3Where:

Q

Ac

yo.

==

=

=

Shear force.

Area of the concrete section without haunches.

Distance between central axis of the concrete sect'and that of the composite section. Ion

Moment of inertia of the composite section about itscentral axrs.

10.1.7.2.2 Uplift of Concrete Slab

a- Shear connectors shall be capable of providing resistance touplift of the concrete slab by designing it to support a tensileforce perpendicular to the steel flange of at least 10% of theallowable horizontal load, carried by the connector; Clause10.1.7.3. If necessary, shear connectors shall be provided withanchoring devices.

b- The surface of the connector that resists separation forces(i.e., the inside of a hoop or the underside of a head of a stud)shall extend not less than 40 mm clear above the bottomreinforcement of the slab.

Total horizontal shear to be transmitted by 0an interval or pitch e: ne connector along

=(Q A, y, e) Ilv =D

e = D ( 'v I Q Ac Yo) .................. , ....... . 10.4

10.1.7.2.3 Concrete Cover

a- In order to ensure adequate embedment of shear connectorsin the concrete slab, the connector shall have at least SO mm oflateral concrete cover (Fig. 10.3). On the other hand, theminimum concrete cover On top of the connector shall not beless than 20 mm.

Thus the pitch e is inversely proportional to Q and thconnectors are to be arranged closer to each other at th eand at bigger intervals near the middle of the beam. e supports

It is preferable to use sh .bearing front areas spaced at

e:rr~fa~~:e~O~m:::hPi~~~t:~e~rd:~~"

ensure a better dispersion of the pressure in the concrete mass. 0

10.1.7.2 Requirements of Shear Connectors

10.1.7.2.1 Connection to Steel Flange

The connection between the shear connectors

tfhlange shall be designed to resist the horizontal shear~~~ thect·beam

e connector: Clause 10.1.7.3. ,a 109 On

b- Except for formed steel stabs: the sides of the haunch shouldlie outside a line drawn at a maximum of 4So from the outsideedge of the connector. The lateral concrete cover from the sideof the haunch to the connector should not be less than 50 mm(Fig. 10.3).

10.1.7.2.4 Reinforcement in Concrete Slab

Reinforcement in the slab shall be designed as per the EgyptianCode of Practice for the Design of Reinforced Concrete Structuresto avoid longitudinal shear failure or splitting of the slab at the edgeof the steel beam upper flange.

10.1.7.2.5 Placement and Spacing

In builuings only, shear connectors required at each side of thepoint of maximum bending moment, positive or negative. may be

Composite Slee/·ConcrateConstruction 166 Composite Steel-Concrete

Construction167

Anchors

cf23rI

concrete cover ;" 3~L;,,4rr z 7.5~

h and concrete cover of anchors shail

~~ ~:~:~o~~:~~ ~efl~gtpwabctlec~o~~;e;~:o~~s~:s~~s~:i~f:~:~Egyptian Code 0 ra I

Concrete Structures.

distributed uniformly between that point and the adjacent points ofzero moment. However, the number of shear connectors betweenconcentrated loads and the nearest point of zero moment shail besufficient to develop the required horizontal shear between theconcrete slab and the steei beam.

• 60 cm

• Three times the total slab thickness (do)

• Four times the connector height includinq hoops or anchors, ifany.

Except for stud connectors, the minimum center to centerspacing of shear connectors shall not be less than the total depth ofthe slab inClUding haunch, do. The maximum center to centerspacing of connectors shail not exceed the least of the foilowing:

However, the maximum spacing of connectors may be exceededOver supports to avoid placing connectors at locations of high tensilestresses in the steel beam upper flange.

10.1.7.2.6 Dimensions of Steel Flange Hoops

10.1.7.2.7 Anchors and hoops

b- Hoop connectors (diameter =~) shall satisfy the foilowing(Fig 10.10)

a- Anchors and hoops (Fig. 10.1 O) designed for longitUdinalshear should point in the direction of the diagonal tension. Wherediagonal tension can OCCur in both directions, connectorspointing in both directions should be providert

The thickness of steel flange to which the connector is fastenedshall be sufficient to ailow proper welding and proper transfer of loadfrom the connector to the web plate without causing iocal failure orexcessive deformations. The distance between the edge of aconnector and the edge of the fiange of the beam to which it iswelded should not be less than 25 mm (Fig. 10.3).

189Composite Steel·ConcrefeConstruction

Figure (10.1a) Anchor & Hoop Shear Connectors

10.1.7.2,8 Block Connectors

a Block connectors (Fig. 10.11) shail be provided witha~choring devices to prevent uplift of concrete slab.

b- The height of bar connectors shall not exceed four times itsthickness.

c- The height of T-sections shall not exceed ten times the flangethickness or 150 mm, whichever IS the ieast.

b h t roiled with a web width notd- Channel sections Sh~1 W:b ~hickness. The height of theexceeding 25 times th d 15 times the web thickness nor 150connectors shall not exceemm, whichever is the least.

168comoosse Stee~ConcreteConstruction

e- The height of horseshoe connectors shall not exceed 20 timesthe web thickness nor 150 mm, whichever is the least.

10.1.7.2.9 Stud Connectors

The length of the stud connectors shall not be less than fourtimes its diameter, d, after installation. The nominal diameter of thestud head shall not be less than one and a half times the studdiameter, d, (Fig. 10.12). The value of d, shall not exceed twice thethickness of the top flange of the steel beam.

t !~ +A~]1c

~Block Connector with hoop

Block Connector with anchor

Figure (10.11) Block Shear Connectors

T-section with anchor

Channel section with hoop

Horseshoe connector with hoop

A1 A2

~/.::::'C::'

fDefinition of area (A2)

Figure (10.11) Block Shear Connectors (Cont.)

Composite Stee/~Concrete

Construction 170Composite Steel-ConcreteConstruction

-

171

Except for formed steel decks, the minimum center to centerspacing of studs shall be 6d, measured along the longitudinal axis ofthe beam; and 4d, transverse to the longitudinal axis of thesupporting composite beam, (Fig. 10.13).

~ 1.Sd,

o(a) Stud Connectors

If stud connectors are placed in a staggered configuration, theminimum transversal spacing of stud central lines shall be 3d,.Within ribs of formed steel decks, the minimum permissible spacingshall be 4d, in any direction.

10.1.7,2.1O'Angle Connectors

The height of the outstanding leg of an angle connector shall notexceed ten times the angle thickness or 150 mm, whichever is thesmaller. The length of an angle connector shall not exceed 300 mm(Fig. 10.12).

10,1.7.3 Allowable Horizontal Shear Load for Shear Connectors

Ie

(b) Channel Connectors

~3rz:;

~.'1

,./~' --::::;:EC=F=e-~

This section applies to the calculation of the allowable horizontalshear load, Roo, in tons, for one connector. The value of Roocomputed from the following formulas shall not exceed the allowablehorizontal load, Rw, provided by the connector connection to thebeam flange.

10.1,7.3.1 Anchors and Hoops

The allowable horizontal load for each leg of anchors and hoopssatisfying the requirements of Clause 10.1.7.2 shall be computed asfollows:

10.5

Allowable horizontal load per connector in tons.Cross-sectionalarea of anchor or hoop, em'.Yield stress of anchor or hoop material, Vcm'.Angle in horizontal plane between anchor andiongitudinal axis of the beam (Fig. 10.11).Angle in the vertical plane between anchor or hoopand the beam upper flange (Fig. 10.11).

=

=

=

• 2 Y2R,c = 0,58 A, Fy,cos ~ I (1 + Sin a] s Rw ...

Where:Rsc =A,Fys =

~

Figure (10.12) Stud Shear Connectors

(c) Angle Connector

Composite Steel-ConcreteConstruction 172 Composite Steel-Concrefe

Construction173

concrete section shall be taken in.to account.= Characteristic compressive' cube strength of

concrete after 28 days, kg/em'.

Figure (10.13) Minimum Spacing of Stud Connectors

10.1.7.3.2 Block Connectors

10.8

10.7

Roo = Rbi + 0.7 Rh" Rw

Where:Ran = Horizontal load supported by anchor (Clause 10.1.7.3.1)Rh = Horizontal load supported by hoop (Clause 10.1.7.3.1).

and

10.1.7.3.3 Stud Shear Connectors

Block connectors shall be provided with anchors or hoops sharingpart of the horizontal load supported by the connector, provided thatdue account shall be taken of the differences of stiffness of the blockconnector and the anchors or hoops. The allowable horizontal loadper connector can be computed from the following:

Norro" Ilon',l"

++ '.++•t,

"Wide Ilange

Block connectors such as bar, T-section, channel section andhorseshoe connectors meeting the requirements of Clause 10'1 72can be used as shear connectors. The front face shall not be ';'edgeshaped and shall be so stiff that a uniform pressure distribution onthe concrete can be reasonably assumed at failure. The allowablehonzontalload (Rbi In tons) transmitted by bearing can be computedfrom the tollowing Equation:

Rbi = 0.3 ~ A, fou xl0"

Composite Sfeel·ConcreteConstruction 175

= Cross-sectional area of stud connector, em'.= Concrete compressive strength, kg/em'.= Modulus of elasticity of concrete, Vern'.= The yield stress of stud shear connectors;' 3.40 Vcm'

and the tensile strength;' 4.20 Vern'.

Where:

The allowable horizontal load, R,e, for one channel shearconnector (Fig. 10.14), conforming to the requirements stated in

-3 %R'e=5.4xl0 A'elfeuEel "Rw 10.9

• s 0.58 A,e Fy

Composite Steet-ConcreteConstruction

10.1.7.3.4 Channel Shear Connectors

The allowable horizontal load, Roo, in ton, for one stud connectorconforming to the requirements stated in Clause 10.1.7.2 shall becomputed from the following formula:

10.6.......................

174

(A,/A,) '/2" 2.0.Area of connector front face. em'.Bearing area on concrete, in em', and shall be takenas the front area of the connector. A,. enlarged at aslope of 1:5 (see Fig. 10.11) to the rear face of theadjacent connector. Only parts of A, falling in the

==

=

Where:'1A,A,

Clause 10.1.7.2 shall be computed from the following Equation:

Flange thickness of channel shear connector. cm.

Web thickness of channel shear connector, em.Length of channel shear connector, em.Concrete compressive strength, kg/em'.Modulus of elasticity of concrete, t/crrr'.

10.1.7.3.5 Angle Connector

10.11

Lengthof angle shear connector, em.

Width of the outstanding leg of angle connector, em.Concrete compressive strength, kg/cm'.Allowable horizontal load per connector, tons.

Where:t, =t, =feu =RK =

The allowable horizontal load for an angle connector welded tothe beam top flange and satisfying the requirements of Clause10.1.7.2 shall be computed as follows:

10.10R,e = 3.80x10·'( tf + 0.5twl t; (feu s, 1' 12 ,; Rw

Where:If =tw =

L, =feu' =Ec :;

A-+

It is recommended to provide a bar welded to the angle toprevent uplift of the concrete slab. the minimum diameter of the barshall be computed from the following:

... 1/2'I' ;, 0.45 (Rse / Fy. ) 10.12

The length of the bar on each side of the angle connector'soutstanding leg shall be computed based on the allowable bondstrength of concrete according to the provisions of the EgyptianCode of Practice for the Design of Reinforced Concrete Structures.Sec (A-A)

Where:

<I>=

Fy, =R,e =

Diameter of the bar, em.

Yield stress of the bar, kg/em'.

Allowable horizontal load per connector, tons.

10.2 COMPOSITE COLUMNS

Figure (10.14) Channel Shear Connectors10.2.1 Scope

This section is applied to the design of steel columns fabricatedfrom rolled or buiit-up steel sections and encased in concrete or

Composife Steel-ConcreteConstruction 176 Composite Steel-Concrete

Construction 177

1

concrete-filled hollow steel pipes or tubing. Typical types ofcomposite columns are illustrated in Fig. 10.15.

10.2.2 Requirements

In order to qualify as a composite column. the followingrequirements shall be fulfilled:

a- The total cross-sectional area of the steel section shall not be lessthan four percent (4%) of the gross column area. If this condition isnot satisfied, the member will be classified as a reinforced concretecolumn and its design will be handled by the Egyptian Code ofPractice for the Design of Reinforced Concrete Structures.

e- To avoid local buckling, the minimum wall thickness of steelrectangular tubing filled with concrete shall be taken as b(Fy/3E.)"2for each face of widtn b of the tube section. The minimum wallthickness for circular sections of outside diameter, D, shall be takenas D(Fyl8E.)"2.

f- To avoid overstressing of concrete at connections, the portion ofthe load carried by the concrete shall not exceed the allowablebearing stress that will be computed as given by the Egyptian Codeof Practice for the Design of Reinforced Concrete Structures, Fig.10.16.

•Figure (10.15) Sections for Composite Columns

Ry

1 .- "1"(A2

Sec. (y-y)

t(ff)~

(c) Concrete filledcircular ttl be

b,

~RSJb'j 8.J

(b) Concrete filledrectangular tube

(0) Concrete encasedI-section

b- The characteristic 28-day cube strength of concrete, feu, shall notbe less than 250 kg/cm', nor greater than 500 kg/cm'.

c- Multiple steel shapes in the same cross-section shall beinterconnected with lacing, tie plates, or batten plates to preventbuckling of individual shapes before hardening of concrete.

d- Concrete encasement shall be reinforced with longitudinal loadcarrying bars and lateral ties (stirrups) to restrain concrete andprevent cover spalling. The spacing of lateral ties shall not exceedtwo thirds of the least dimension of the composite section, or 30 cm,whichever is smaller. The cross-sectional area of lateral ties andlongitudinal bars shall be at least 0.02 cm' per cm of bar spacing.Concrete cover over lateral ties or longitudinal bars shall not be lessthan 4 cm.

Fopp.=R/A,<0.3feu ~::

where ~ ~~ <; 2.0

Figure (10.16) Bearing on Composite Columns at Connections

10.2.3 Design

The allowable compressive axial stress, Fe, for symmetric axiallyloaded composite columns shall be computed on the steel sectionarea utiliZing a modified radius of gyration, yield stress and Young's

modulus, Im, Fym, and Em respectively, to account for the compositebehavior.

Composffe Sfeel-ConcreteConstruction 178

Composite Steel-ConcreteConstruction 179

Where:

F,m = F, + C, F" (A,/A,) + C, feu (Ac/As).Em = Es + C3 e, (Ac/A,).a = (0.58 x 10' F,m - 3.57 Em) I (10' F,m)'.feu = 28-day cube strength of concrete.A. = Slenderness ratio =kllrm.K! = Buckling length, bigger of in-plane and out-of-plane

buckling lengths.rm = Radius of gyration of the steel shape, pipe or tubing

except that for steel shapes encased in concrete itshall not be less than 0.3 times the overall width ofthe composite column in the plane of bending.

F,m = Modified yieid stress, t/crrr'.

F, = Yield stress of steel section, t/crn"

F" = Yield stress of longitudinal reinforcing bars, t/crn"

Em = Modified Young's rnoduius, t/crrr', ;, Es.Es = Young's modulus of steel, t/crn".

Ee = Young's modulus of concrete, tlcm' (see Table 10.1)

A, = Area of steel section, pipe or tubing. ern".

A, = Area of longitudinal reinforcing bars, crrr'.Ae = Area of concrete, cm/, excludinq As and Ar.

For inelastic buckling, A. ,;100

Fe = ( 0.58- CL F,m)..') F,m

For elastic buckling, A.;, 100

Fe = 3.57 Em I)..' .

181

Where:fea = Actual compressive stress due to axial force computed

on steel section only.Fe = Allowable compressive stress computed as per Clause

10.2.3,A, = Cmx I (l-fea/F.mx);' 1.0,A, = Cm, I (l-fea/F.my);' 1.0,Cmx, = Moment modification factors as per Clause 2.6.7.1.Cmy

fbxl fby = Applied bending stress based on moments about the xand y axes, respectively, and neglecting compositeaction.

Fy = Yield stress.Femx, = Modified elastic buckling stress for buckiing In x and yFemy directions, respectively.

Femx = 3.57 Em I)..x'.Ferny = 3.57 EmI)",',

10.3 COMPOSITE BEAM-COLUMNS

For cases when fea/Fe < 0.15, A, = A2 = 1.0

10.3.1 Axial Compression and Bending

Composite members subject to bending in addition to axialcompression may be proportioned to satisfy the following interactionEquation:

10.3.2 Axial Tension and Bending

The interaction Equation used in the design of a beam-columnmay be computed on the basis of the section properties of thecomposite section neglecting the concrete in tension. Alternatively,

Composite steel-ConcreteConstruction

10.13

10.14

180

c., C2, and cJ =numerical coefficients taken as follows:For concrete encased sections,

c. =0.7, c, =0.48, and C3 =0,20,For concrete filled pipes or tubing,

c, =1,0, ca =0,68, and C3 =0.40.

Composite Steel-ConcreteConstruction

composite members subjected to combined axial tension andbending shall be proportioned by neglecting the concrete.

1r

CHAPTER 11

COLD-FORMED SECTIONS

11.1 GENERAL

This Chapter shall apply to the design of members made of cold­formed steel sheet, strip or plate and used for load carrying purposesin bUildings.

11.2 CLASSIFICATION OF ELEMENTS

Cold-formed members generally have as their components flatslender thin plates with flat width-thickness ratios that do hot meet thenon-compact section requirements of Table 2.1. The individual plateelements are classified as stiffened, unstiffened and multiple stiffenedelements depending on the stiffening arrangement provided.

11.3 MAXIMUM AND MINIMUM THICKNESS

The provisions of this Chapter apply primarily to steel sections witha thickness of not more than 8 mm although the use of thickermaterial is not precluded. The minimum thickness of plates for cold­formed members used for load-carryingpurposes in buildings shall betaken as 1.25 mm while for sheets the minimum thickness shall beO.5mm.

11.4 PROPERTIES OF SECTIONS

The properties of sections shall be detenmined for the full crosssection of the member except that tile section properties forcompression elements shall be based on the effective design width asspecified in Table 2.3 for stiffened elements and Table 2.4 forunstiffened elements (see Clause 2.6.5.5), and the section propertiesfor tension elements shall be based on the net area. The effectivedesign width for compression elements with edge stiffeners ormultiple stiffened elements and the stiffener requirements aredetailed in Clause 11.9.

Composite Steel-Concrete­Construction 182

Cold-Formed Sections 183

l,

11.5 MAXIMUM ALLOWABLE FLAT WIDTH-THICKNESS RATIOSFOR COMPRESSION ELEMENTS Where I, and I, are the adequate and the actual moment of inertia of

the stiffener as detailed in Clause11.9.1.

The following Table gives the maximum allowable flat width­thickness ratios for compression elements. The definition of flat widthfor the different elements is shown in Fig. 11.1.

11.6 MAXIMUM ALLOWABLE WEB DEPTH-THICKNESS RATIOSFOR FLEXURAL MEMBERS

Figure (11.1) Definition of Flat Width of CompressionElements

Figure (11.2) Definition ofWeb Depth

185

Depth of flat portion ofweb measured along theplane of web.Web thickness.

Table (11.2) Maximum Allowable Web Depth-Thickness ~atiosfor Flexural Members

Where:dw =

Where a web consists of twoor more sheets, the d.,ltw ratioshall be computed for theindividual sheets.

Description Max. dwltwUnstiffened webs. 200Webs which are orovided with bearingstiffeners onlv. 260Webs which are provided with bearing stiffeners and

300intermediate transverse stiffeners.

11.7 MAXIMUM ALLOWABLE DEFLECTION

The fallowing Table gives recommended deflection limits for somestructural members. Circumstances may arise where greater or lesservalues would be more appropriate. Other members may also requirea deflection limit to be specified, e.g., sway bracing.

The determination of the moment of inertia, I, used in computingbeam deflection, shall be based on the effective section properties,for which the effective widths are computed for the compressivestresses developed from the applied bending moment. The actualcompressive stresses due to applied moment shall be used to

compute the normalized plate slendemess, i p . rather than Fy

Cold-Formed Sections

J[

184

t j, t"2

Table (11.1) Maximum Allowable Flat Width-Thickness Ratios forC pres ion Elements

Cold-Formed Sections

om s

Description Max. bitor Cit

Unstiffened compression eiements (C, and C,). 40Stiffened compression element having one longitudinaledge connect,:d to a web or flange element, the otherstiffened by: (b ,)

60Simple lip.Any other kind of stiffener:

60i) when 1$< l:a.90iI) when Is :2: la'

Stiffened compression element with both longitudinal300edges connected to other stiffened elements (b,I.

11.2

11.3

187

2- When S/3 < bit < S

I. = 399 { [ (b Itll S 1- 0.33 )' t4

C, = IJI.:S 1C, = 2-C,For simple lip stiffener with 140° <: e <: 40' and0.25 < 01b s 0.8 and 8 is as shown in Fig. 11.3, theeffective width for the flange is determined as:

b. = p b accordingto Table 2.3 with the fallowing k"ko = [4.82:" 5(D/b II (1,/1.)'12 +0.43,; 5.25 - 5(D/b IFor simple lip stiffener with 140° <: 8 <: 40° and0.25 <: Dlb, the value of k" becomes:

k" = 3.57 (1,/1.)'12+ 0.43,; 4

The effective width of the stiffener is determined fromTable 2.4 as: d', = P d with the value of k"=0.43do = C, d's = (VI.) d',A', = d's t; A.= (IJI.) A',

3- When b /t <: S

I. = {[115 (b/tll SI + 5 }t4

C, = IJI.:S 1C, = 2-C,For simple lip stiffener with 140° <: 8 <: 40° and0.25 < D/b :s 0.8 and 8 is as shown in Fig. 11.3, theeffective width for the flange is determined as:b. = P b according to Table 2.3 with the following k"k. = [4.82 - 5(D/b)] (1,/1.)'13+ 0.43'; 5.25- 5(D/blFor simple lip stiffener with 140° <: 8 <: 40° and0.25 <: Dlb, the value of k"becomes:

k" = 3.57 (1,/1.)'/' +0.43,; 4

The effective width of the stiffener is determined fromTable 2.4 as: d's = P d with the value of k"=0.43d, = C, d', = (IJI.) d'sA', = d', t; A.= (IJI.) A's

CoJd-Formsd Sections

11.9.1 Effective Width of Uniformly Compressed Elements withan Edge Stiffener1- When b/tSS/3

I, = 0 (no edge stiffener required)

b.=b 11.1d's = d; d, =d's for simple lip stiffenerA's=d'stA, = A', for other stiffener shapesI, = d't/12

Cold-FormedSections 186

11.9 EFFECTIVE WIDTHS OF COMPRESSION ELEMENTS WITHAN EDGE STIFFENER OR AN INTERMEDIATE STIFFENER

11.8 ALLOWABLE DESIGN STRESSES

The allowable stresses shall follow the slender section designrequirements as detailed in Clause 2.6.5.5. Thus, for members underaxial compression. axial tension, bending, shear, web crippling, orcombined axial compression and bending, the requirements ofChapter 2 shall apply. However the allowable stresses for cylindricalt..oular members shall be as given in Clause 11.13.

Table (11 3) Maximum Allowable Deflection

in Clause 2.6.5.5.

Deflection of beams due to live load without dynamic effectBeams carrying plaster or other Span 1300brittle finish.Ali other beams. soan 1200Cantilevers. Lenath / 180Puriins and side girts (rai's), To suit the characteristics of

the oarticular claddino svstem.!:leflection of columns other than portal frames due to live andwind loadsTops of columns in single-storey

Height / 300buildinas.In each storey of a building with Height of storey undermore than one storev. consideration / 300

1i

b

11.8

11.7

11.9

11.9.2 Effective Width of Uniformly Compressed Elements withOne Intermediate Stiffener

component element can behave as a stiffened element.I.. A', = Moment of inertia of the full section of the stiffener about

its own centroidal axis parallel to the element to bestiffened, - and the effective area of the stiffener,respectively For edge stiffeners, the round comerbetween the stiffener and the element to be stiffenedshall not be considered as part of the stiffener.For the stiffener shown in Fig. 11.3.1,=(d'tsin'O)/12 11.5A',=d',t 11.6

1- When bolt s SI, = 0 (no intermediate stiffener nequined) }be = bA, = A', =area of intermediate stiffener, Fig. 11.4b.

2- When S < bolt < 3SI. = { [50 (bolt) I SI- 50} t"The effective width for the flange is determined as:

be = P b according to Table 2.3 with the following I<.1<.=3(1,/1. )'12+ 1 '; 4

The reduced intermediate stiffener area is calculatedfrom:A, = A', ( 1,/1. ) SA',

Where I, is the moment of inertia of the intermediatestiffener about the x-xaxis, as shown in Fig. 11.4b.

3- When bolt;:: 3SI. = { [ 128(bolt) I SI - 285} t" }The eff~ctive width for the flange is determined as:

be = P b according to Table 2.3 with the following k.k. =3 ( I,/i. )"3 + 1,; 4

A, = A', ( Is/I. ) SA',

11.4

Dimensions defined in Fig. 11.3.

t :.~:--

b

=bd, =

D', =C11 C2 =

A, =

Reduced effective width of the stiffener. d, shall be usedin computing the overall effective section properties.Effective width of the stiffener according to Table 2.4.Coefficients defined according to Fig. 11.3 to calculatethe effective width instead of Table 2.3.Reduced area of the stiffener. It shall be used incomputing the overall effective section properties. Thecentroid of the stiffener is to be considered located at thecentroid of the full area of the stiffener.

I, = Adequate moment of inertia of the stiffener, so that each

Figure (11.3) Elements with Edge Stiffener

In the previous equations:

5 = 1.28JE/Fy

Fy = Yield stress.K. = Plate buckling factor.8, = Dimension defined in Fig. 11.4.D,d,

Cold-Formed Sections 188Cold-Formed Sections 189

Minimum moment of inertia of the full stiffener about its owncentroidal axis parallel to the element to be stiffened.

= Flat-width to thickness ratio of the larger stiffened subelement.

bit

Where:Imin =

( a )

bb.

I I I

( b )

11.9.3.2 Effective Design Width of Sub Elements

For multiple-stiffened compression elements, the effective widthsof sub elements are determined by the following Equations:

Figure (11.4) Elements with Intermediate Stiffener 1- If bit,; 60

2- If bit> 60

bern = beb.m=b.-0.10t[b/t-60] ..

11.11

11.12

- - -Where: a = [3- 2 bem/b]-1/30 [1- bemIb] [bit]

11.13

Aeff = a. A" 11.14

Aeff=[bem/b).A" 11.15

Aeff = A" .

bit;, 90

bit,; 60

2- If 60 < bit < 90

3- If

1- If

bem

Where'bit = Flat-width to thickness ratio of element or sub element.

= Effective design width of element or sub element to beused in design computations.

= Effective design width determ~ed for single-stiffenedcompression element (em) with b as shown in Fig. 11.5a(refer to Table 2.3).

11.9.3.3 Effective Stiffener Area

In computing the effective structural properties for a memberhaving intermediate stiffeners and when fhe ii It ratio of the subelement exceeds 60, the effective stiffener area (A.t,) (edge stiffeneror intermediate stiffeners) shall be computed as follows:

Figure (11.5) Sections with Multiple-Stiffened CompressionElements

Intermediate stiffeners of an edge stiffened eiement or thestiffeners of a stiffened element with more than one stiffener asshown in Figure 11.5 shall have a minimum moment of inertia (Imln inem') given by:

11.9.3.1 Minimum Intermediate Stiffener Inertia

11.9.3 Effective Width of Edge Stiffened Elements withIntermediate Stiffeners or Stiffened Elements with More thanOne Intermediate Stiffener

11.10

Cold-Formed Sections 190Cold·FormedSections 191

where A,t is the area of the relevant stiffener, Fig. 11.5.b.

In the above Equation, A.ffand A,t refer to the area of the stiffenersection, exclusive of any portion of adjacent element. In thecalculation of sectional properties, the centroid of the full section ofthe stiffener and the moment of inertia of the stiffener about its owncentroidal axis shall be that of the full section of the stiffener.

11.10 BEAMS WITH UNUSUALLY WIDE FLANGES

For beams with unusually wide flanges, special consideration shallbe given to the effects of shear lag and flange curling, even if thebeam flanges, such as tension flanges, do not buckle.

Table (11.4) Maximum Ratio of Effective Flange Width to ActualWidth

Effective Effective

Uw,Flange Width I

UWfFlange Width I

Actual ActualFlange Width Flange Width

30 1.00 14 0.8225 0.96 12 0.7820 0.91 10 0.7318 - 0.89 8 0.6716 0.86 6 0.55

11.10.2 Flange Curling

11.10.1 Shear Lag Effect

11.11 COMPRESSION MEMBERS

Flange thickness.Overali depth of the section.Average bending stresses in the flange in full, unreducedflange width.

=f"

Where:t =d =

The width of the flange projection beyond the web, Wf, for C­beams or similar, or half the distance between webs of multiple websections (whether the flange is in tension or compression, stiffened orunstiffened) shall not exceed the following to avoid flange cuning:

w,=0.37{tdE/f,,}'12 11.16rWf

r':Figure (11.6) Definition of (Wf) of Compression Elements 11.11.1 Slenderness Ratios

The ratio of effective flange width to the actual width as perClause 2.6.5.5 shall not exceed the values specified in Table 11.4.The effective span length of the beam, L, is the full span for simplebeams, the distance between inflection points for continuous beams,or twice the length of cantilever beams. The symbol, w" is defined asshown in Fig. 11.6.

The maximum slendemess ratios of compression members shallbe according to Clause 4.2.1.

11.11.2 Effective Buckling Length (KI)

The affective buckling length (KI) of a compression member maybe taken from Table 4.4, or obtained from an elastic critical bucklinganalysis.

CoJd·Formed Sections 192Cold-Formed Sections 193

11.19

11.18fb =[0.45+(2~~~y )}Y .

For 580 I Fy < Oil S 735 I Fy

Fb=[~~~] .

Where Fy is in Vern'

The elastic"section modulus to be used in the calculations shall befor the full, unreduced cross section.

11.13.4 Allowable Stress for Members under Compression

11.12 TENSION MEMBERS

11.12.1 Slenderness Ratios

The maximum slenderness ratios of tension members shall beaccording to Clause 4.2.2.

11.12.2 Effective Area

The properties of the cross section shall be computed from theeffective net sectional area, in case of using bolts for connections.Effective net area shall be according to Clause 2.7.1.11.13 CYLINDRICAL TUBULAR MEMBERS

The follOWing Equations shall be used to define the allowablecompressive stress, F" for circular tubes:

The thickness of the cylindrical tubular members shall be chosensuch that the ratio of outside diameter to wall thickness, DII, shall notexceed 735 I Fy .

11.13.1 Slenderness Ratios

The maximum slenderness ratios of cylindrical tubular membersshall be according to Clause 4.2.

For he S 1.5

For he > 1.5

F, = (0.658~r:F, = [0.~37]Fy

• A:c ,

11.20

11.21

11.13.2 Effective Buckling Length (KI)

11.13.3 Allowable Stress for Members under Bending

The allowable bending stress (Fbl in a cylindrical tubular membershall be calculated as follows:

The effective buckling length (KI) of a cylindrical tubular membermay be taken from Table 4.4, or obtained from an elastic criticalbuckling analysis.

Where:

he= ~Fy IF• •and

FAe. = [1-{1- -y- ){l-Ao1A)].A 11.22

2F.

,,2EF. = The flexural buckling stress =~)2

,Ki/r

The effective area to be used for calculating the axial strength, Ae.shall be detenmined as follows:

Where 'A= Area of the full, unreduced cross section.11.17.............................. " .

For DII S 140/FyFb = 0.64 Fy

For 140 I Fy < DII S 580 I FyCold-Formed Sections 194 Cold-Fanned Seclions 195

11.13.5 Allowable Stresses for Members under CombinedBending and Compression

Combined bending and compression shall satisfy the requirementsof Clause 2.6.7.1.

11.14 SPLICES

Splices in compression or tension members shall be designed onthe actual forces in the members.

11.15 CONNECTIONS

Connections of members at an intersection shall be designed onthe actual forces in the members.

11.15.1 WELDED CONNECTIONS

The following design criteria govern Arc welded connections usedfor cold-formed steel structural members in which the thickness of thethinnest connected part is 4 mm or less. For welded connectionswhere the thickness of the thinnest connected part is greater than 4mm, the provisions of Chapter 5 shall apply.

Resistance welds, which are produced by the heat obtained fromresistance to an electric current through the work parts held togetherunder pressure by electrodes, are possible.

11.15.1.1 Arc Welds

Several types of arc welds are generally used in cold-formed steelconstruction such as:

~t I o~~t B II t~

Figure (11.7) Groove Welds in BUll Joints

11.15.1.1.1 Groove Welds in BUll Joints

In the design of groove welds in butt joints, the allowable stress intension or compression is 0.7 times for tension or the same forcompression, as that prescribed for the iower strength base steel inconnection, provided that an effective throat is equal to or greaterthan tl.e thickness of the material, and that the strength of the weldmetal is equal to or greater than the strength of the base steel.

11.15.1.1.2 Arc Spot Welds

1- Arc spot welds should not be used to weld steel sheets where thethinnest connected part is over 4 mm thick, nor through acombination of steel sheets having a total thickness of over 4 mm.

2- Weld washers should be usedwhen the thickness of the sheet isless thar. 0.7 mm. Weld washers should have a thickness of between1.3 mm and 2 mm with a minimum prepunched hole of 10 mmdiameter.

3- The minimum allowable effective diameter d. is 10 mm.

4- The distance measured along the line of application of force fromthe centerline of a weld to the nearest edge of an adjacent weld or tothe end of the connected part toward which the force is directedshould not be less than the value of em'. as given by:

1- Groove welds, 2- Arc spot welds, 3- Arc seam welds. 4- Filletwelds, and 5- Flare groove welds.Cold-Fanned Sections 196 Cold-Formed Sections 197

5- The distance from the centerline of any weld to the end orboundary of the connected member should not be less than 1.5d. Inno case should the clear distance between welds and end of memberbe less than d.

Force transmitted by an arc spot weld.Thickness of thinnest connected sheet.Specified minimum tensile strenglh of sleel (base metal). de =

I =

Fy =

Fu =

Where:P =I =Fu =

P

0.4 Fu I.............................................

11.23

.,i

Where:d = Visible diameter of ouler surface of arc spot weld.

d = Averane diameter of arc spot weld at mid-thickness of I. '"(as shown in Figure 11.8) = d - I for single sheet. and= d - 21 for multiple sheets (not more than four lappedsheets over a supporting member).Effective diameter of fused area = 0.7 d -1.5 1:5 0.55 d.Total combined base steel Ihickness (exclusive ofcoaling) of sheets involved in shear transfer.Specified minimum yield stress of steel.

Specified minimum tensile strength of steel.

6- The allowable load on each arc spot weld between sheet or sheetsand supporting member shall not exceed the smaller value of theloads computed by the following Equations:

i- Allowable load based on shear capacity of weld

P.=0.3Fultd.'/4 11.24

ii- Allowable load based on strength of connected sheets

a- For 36 I.JF:; ? d. II

p. = 0.8 Fu d. I 11.25

b- For 36 I.JF:; < d. It < 64 I.JF:;

240 .p. = 0.105 Fu (1 + r;;- ) d. I

d./lvFu11.26

Figure (11.8) Definilion of d, d. and de in Arc Spol Welda- Single Sheel b- Double Sheel

c- For d. II ? 64 I .JF:;p. = 0.5 Fu d. I 11.27

11.15.1.1.3 Arc Seam Welds

For arc seam welds, the allowable load on each arc seam weldshall be laken as Ihe smaller of the values computed by the followingEquations:

Cold-Formed Sections 198Cold·Formed Sections 199

Figure (11.1OJ Fillet Welds

11.30

!--t>I

Pa = 0.2 Fu (s L)

i- Allowable load based on shear capacity of weld

Pa = 0.4 Fu (0.625 L + 2.4 da) t 11.29

i- 'Allowable load based on shear capacity of weld2 'Pa = 0.3 Fu (1t d. /4 + L d.) 11.28

ii- Allowable load based on strength of connected sheets

Figure (11,9) Arc Seam Weldsii- Allowable load based on strength of connected sheets

a- Longitudinal loading

b- Transverse ioading

Where:d = Width of arc seam weld.L = Length of seam weld not including circular ends, (L < 3d).

d., da, and Fu are as defined in arc spot welds.

when Ut < 25

when ut;" 25

Pa = 0.4 Fu ( 1 - 0.01 Ut) (t LJ

Pa = 0.3 Fu (t L)

11.31

11.32

Pa = 0.4 Fu (t LJThe requirements for minimum edge distance are the same asthose for arc spot welds.

11.15.1.1.4 Fillet Welds

The allowable load for a fillet weld in lap and T-joints shall notexceed the values computed by Equation 11.30 for the shear strengthof the fillet weld and by Equations 11.31,11.32, and 11.33 for thestrength of the connected sheets as follows:

Where:L =

11,33

Length of fillet weld.Leg sizes of fillet welds, use whichever is smaller.

Cold-Formed Sections 200Cold-Formed Sections 201

Figure (11.11) Leg Sizes of Fillet Weldsa- Lap Joint b- T-Joint "Pa (Longitudinal)

s, r-";

:F ~{L

(a)~

(b)

11.15.1.1.5 Flare Groove Welds

The allowable load for each flare groove weld shall be determinedas follows:

Figure (11.12b) Longitudinal Flare Bevel Weld

i- Allowable load based on shear capacity of weld

Pa=0.3FuLs 11.34

ii- Allowabie load based on strength of connected sheets

a- Transverse loading

p. = 0.33 Fu (t L)

b- Longitudinal loading

......................................... 11.35

Figure (11.12a) Transverse Flare Bevel WeldIf t s tw < 2t or if the lip height is less than the weld length,

p. = 0.3 Fu (t L) 11.36

If tw ;, 2t and the lip height is equal to or greater than L,Pa = 0.6 Fu (t L) 11.37

Cold-Formed Sections 202Cold~Fonned Sections 203

11.15.2.1 Minimum Spacing and Edge Distance in Line of Stress

thinnest connected part is 4 mm or less. For bolted connectionswhere the thickness of the thinnest connected part is greater than 4mm, the provisions of Chapter 6 shall apply.

11.38.............................................0.4

emin

The distance (e) measured in the line of force from the center of astandard hole to the nearest edge of an adjacent hole or to the end ofthe connected part toward which the force is directed should not beless than the value of emln determined by:

ad

Where:Figure (11.13) Effective Size Dimension t w for Flare Groove

Welds - Smaller of s, and s,

The definition of tw in such case is as shown in Figure 11.13.

ad

==

Bearing stress coefficient as given in Table 6.2.Bolt diameter.

11.15.1.2 Resistance Welds

Figure (11.14) Spacing and Edge Distance of Bolts

The nominal clearance in standard holes shalloutlined in clause 6.2.2 as follows:

1 mm for M12 and M14 bolts2 mm for M16 up to M24 bolts3 mm for M27 and larger

f gO ti ~I

"'m'\ \g/:~; e

The shear strength of spot resistance welding shall be determinedas given in the following Table:

Thickness Shear Thickness Shear Thickness Shearof Strength of Strength of Strength

Thinnest per Spot Thinnest per Spot Thinnest per SpotOutside Outside OutsideSheet Sheet Sheet(mm) (kg) (mm) (kg) (mm) (kg)0.50 77 1.75 450 3.10 11600.75 160 2.00 530 4.80 16251.00 225 2.25 640 6.40 24001.25 265 2.50 8001.50 360 2.75 975

11.15.2 BOLTED CONNECTIONS

The following design criteria govern bolted connections used forcold-formed steel structural members in which the thickness of theCold-Formed Sections 204

Cold-Formed SectiOns 205

be as previously

In addition to the previous requirement. the following requirementsconceming minimum spacing and edge distance in the line of stressshall also be considered:

1. The minimum distance between centers of bolt holes shall not beless than 3d.

2. The distance from the center of any standard hole to the end orother boundary of the connecting member shall not be less than 1.5d.

3. The clear distance between edges of two adjacent holes shall notbe less than 2d.

4. The distance between the edge of the hole and the end of themember shall not be less than d.

5. For slotted holes. the distance between edges of two adjacentholes and the distance measured from the edge of the hole to the endor other boundary of the connecting member in the line of stress shallnot be less than the value of (emi" • 0.5dh) , in which emi" is therequired distance computed from the above Equation and dh is thediameter of a standard hole.

11.15.2.2 Allowable Tensile Stress on Net Section of ConnectedParts

The allowable tensile stress on the net section of a boltedconnection shall be the smaller of F, or Fll • which is computed byusing the following Equations according to the conditions therein:

i- With washers under both bolt head and nut

Ftt = (1.0 - 0.9 r + 3 r dIg) 0.58Fy ~ 0.58Fy ...•.. 11.39

Where:r = Force transmitted by bolt or bolls at the section considered.

divided by tension force in member at that section. If r isless than 0.2 it may be taken as zero.

g = Spacing of bolts perpendicular to the line of stress. In thecase of a single bolt. g = gross width of sheet.

Ftt = Allowable tensile stress on the net section.

11.15.2.3 Allowable Bearing Stress between Bolts andConnected Parts

The allowable bearing stress Fb between bolts and the partsconnected to them Is taken as detailed in Clause 6.4.2.

11.15.2.4 Allowable Shear Stress on Bolts

The allowable shear stress qb on the gross sectional area of boltsis taken as detailed in Cause 6.4.1.

11.15.2.5 Allowable Tensile Stress on Bolts

The allowable tensile stress FIbon the net sectional area of bolts istaken as detailed in Clause 6.4.3.

11.15.3 SCREWS

The following requirements shall apply to self-tapping screws with2 mm S d S 6 mm. The screws shall be thread-fonming or thread­cutting. with or without a self-drilling point.

Screws shall be installed and tightened In accordance with themanufacturer's recommendations.

Fll = ( 1.0 - r + 2.5 r dIg) 0.58Fy ~ 0.58Fy ...•.. 11.40

li- Without washers under both bolt head and nut. or with only onewasher

Cold-Formed Sections 206

The nominal tension strength on the net section of each memberjoined by a screw connection shall not exceed the member nominaltensile strength from Chapter 2 or the connection nominal tensilestrength from this section.Cold-FormedSections 207

11.15.3.3.2 Shear in Screws

11.15.3.1 Minimum Spacing

The distance between the centers of fasteners shall not be lessthan 3d.

11.15.3.2 Minimum Edge and End Distance

The distance from the center of a fastener to the edge of any partShall not be less than 3d. If the connection is subjected to shear forcein one direction only, the minimum edge distance shall be 1.5d in thedirection perpendicular to the force.

po. =i, =12 =

FU1 =FU2 =

Allowable shear slrenglh per screw (ton).

Thickness of member in contact wittr the screw head (em).Thickness of member not in contact with the screw head(em).Tensile strength of member in contact with the screw head(Ucm').Tensile strength of member not in contact with the screwhead (Ucm').

11.15.3.3 Shear

11.15.3.3.1 Conneclion Shear

The allowable shear strength per screw, Po" shall be determinedas follows:

The allowable shear strength of the screw shall be provided by thescrew manufacturer. .

11.15.3.4 Tension

For screws which carry tension, the head of the screw or washer, ifa washer is provided, shall have a diameter dw not less than 8 mm.Washers shall be at least 1.2 mm thick.

For I,/t, 2 2,5, Po, shall be taken as the smallest of:

For I,/t,,; 1.0, po. shall be taken as the smallest of:

:~:: ~:: :,t~3~~:12 FU2} .

po. = 0.9 12 d Fu2

Po, = 0.91, d FU 1

po. = 0.91, d Fu2}

11.41

11.42

11.15.3.4.1 Pull·Oul

The allowable pull-out strength, POOl, shall be calculated as follows:

Pool= 0.28 te d FU2 11.43

Where r, is the lesser of the depth of penetration and thethickness, t2

11.15.3.4.2 Pull.()ver

The allowable pull-over strength, Poov, shall be calculated asfollows:

For 1.0 < 12/1, < 2.5, Po, shall be detenmined by linear interpolationbetween the above two cases, Pnov = 0.5 t1 dw FU1 11.44

Where:d = Screw diameter (em),Cold-Fanned Sections 208

Where dw is the larger of the screw head diameter or the washerdiameter, and shall be taken not larger than 12 mm.Cold-Formed Sections 209

11.15.3.4.3 Tension in Screws b- For beams

The allowable tension strength, Pnt, per screw shall be determinedby approved tests. The allowable tension strength of the screw shall

not be less than 1.25 times the lesser of Pnot and Pnov

11.15.4 BUILT-UP SECTIONS

11.15.4.11-5ections Composed of Two Channels

The maximum longitudinal spacing of connectors shall be limitedto the following values:

r's- J

SC·

i! "

'm

Ts- =

a· For compression members

Smax = L rcy I ( 2 r, ) 11.45 Figure (11.15) Forces on a Channel of a Built-Up Member

Where:Smax =

L =r, =

11.46

11.47

sm.x=L/62gTs

Smax~-­m.q

=

Span of beam.Vertical distance between the two rows of connectorsnearest to the top and bottom flanges.

= Tensile strength of connectors.Intensity of load.

= Distance between shear center of one channel and midplane of its web.

Where:L =g =

T.qm

Maximum permissible longitudinal spacing of connectors.Unbraced length of compression member.Radius of gyration of the I-section about the axisperpendicular to the direction in which buckling wouldoccur for the giverV conditions of end support andintermediate bracing, if any.

= Radius of gyration of one channel about the centroidalaxis parailel to web.

rcy

For simple channels without stiffening lips at the outer edges:

Cold-Formed Sections 210 CoJd-Formed Sections 211

wI2Wf +d/3

............................... .. 11.48 3- Three times the flat width b of the narrowestcompression element related to the connection .

unstiffened

For C-shaped channels with stiffening lips at the outer edges:

Where:

= Projection of flanges from inside face of web.= Depth of channels.= Thickness of channel section.= Overall depth of stiffening lip.= Moment of inertia of one channel about its centroidal axis

normal to web.

WfdtoI,

m = wfd.t [Wfd + 20(d - 402 J]

4.1. 3d 11.49

Buckled sheet. spacinggrea er an S max.

If Ihe length of bearing of a concentrated load or reaction issmaller than the spacing of the connectors, the required strength ofconnectors closest to the load or reaction Pis:

Figure (11.16) Spacing of Connectors in CompressionElements

Ts = P . m I ( 2 . g )

11.15.4.2 Spacing of Connectors in Compression Elements

11.50

The spacing s, in the line of stress of welds, bolts or rivetsconnecting the compression cover plate or sheet to another elementshould not exceed:

1- That which is required to transmit the shear between the connectedparts on the basis of the design strength per connector, nor

2- s = 50 t I Jf ,where s is the spacing, t is the thickness of the coverplate or sheet, and f is the design stress in the cover plate or sheet,nor

7

Cold-Fonned Secfions 212Cold-Formed Sections 213

CHAPTER 12

DIMENSIONAL TOLERANCES

12.1 GENERAL

Steel structures consist of prefabricated elements which areassembled together in the erection stage. In order to ensure the realsafety of the structure in comparison to the theoretical assumptionconcerning the geometry of the load application, the dimensionaltolerances specified herein shall be observed

12.2 TYPES OF TOLERANCES

12.2.1 Normal Tolerances

Normal tolerances are the basic limits for dimensional deviationsnecessary:

- To satisfy the design assumptions for statically loadedstructures.- To define acceptable tolerances for building structures in theabsence of any other requirements. .

12.2.2 Special Tolerances

Special tolerances are more stringent tolerances necessary tosatisfy the design assumptions:

• For structures other than normal building structures.· For structures in which fatigue predominates.

12.2.3 Particular Tolerances

Particular tolerances are more stringent tolerances necessary tosatisfy functional requirements of particular structures or structuralcomponents, related to:

· Attachment of other structural or non-structural components.- Shafts for lifts (elevators).- Tracks for overhead cranes.- Other criteria such as clearances.

- Alignment of extemal face of building.

12.3 APPLICATION OF TOLERANCES

1. All tolerance values specified in the following shall be treated asnormal tolerances.

2. Normal tolerances apply to conventional single-storey and multi­storey steel framed structures of residential. administrative,commerciai and industrial buildings except where special orparticular tolerances are specified.

3. Any speclal or particular tolerances required shall be detailed inthe Project Specification.

4. Any special or particular tolerances required shall also beindicated on the relevant drawings.

12.4 NORMAL ERECTION TOLERANCES

1. The following normal tolerance limits relate to the steel structurein the unloaded state, i.e., structure loaded only by its own weight,see the following Tables and figures.

2. Each criterion given in the Tables shall be considered as aseparate requirement, to be satisfied independently of any othertolerances criteria.

3. The fabrication and erection tolerances specified in Clauses 12.5to 12.7 apply to the following reference points:

_ For a column, the actual center point of the column at eachfioor level and at the base, excluding any base plates._ For a beam, the actual center point of the top surface at eachend of the beam excluding any endplate.

4. All elements should be checked after fabrication and beforeerection for the allowable tolerances according to Clause 12.5.

Dimensional Tolerances 214Dimensional Tolerances 215

12.5 PERMISSIBLE DEVIATIONS OF FABRICATED ELEMENTS

Deviation amax Fig.Deflection of column fh1 ' ± 0,001 hll generally, 12.1between points which will ± 0,002 hll for membersbe laterally restrained on with hollow cross-section,completion of erection. hl1 is the height between

points which will belaterallv restrained.

Deflection of column fh ± 0,001 h, generally. 12.1between floor slabs. ± 0.002 h, for members

with hollow cross-section.h, is the height betweenfloor slabs.

Lateral deflection of fl1 ± 0.001 Ib1 generally. 12.2compression flange of ± 0.002 Ib1 for membersgirder, relative to the weak with hollow cross-section.axis, between points which

I b, is the length betweenwill be laterally restrainedon completion of erection.

points which will belaterallv restrained.

Lateral deflection of girder. f, ± 0,001 Ib generally. 12.2± 0,002 Ib for memberswith hollow cross-section,{b is the total length ofoirder.

Maximum bow of web for fw hw 1150. 12,3girders and columns (depthof web hw , width of flangeb).Inclination of web between Vw hw/75, 12.3upper and lower flanges.Eccentricity of the web in vw1 b/40 S 10 mm. 12.3relation to the center ofeither flange.Positional deviation of parts e, 7 rnm in anydirection. 12,4connected to a girder orcolumn e.g., cover plate,base plate etc.

12.6 PERMISSIBLE DEVIATIONS OF COLUMN FOUNDATIONS

1- The deviation of the center line for anchor bolts within the groupof bolts at any column base shall not exceed the following:

3- With column rows. the sum of single deviations 32, refenredto thelength L of the row i shall not exceed the value (Fig. 12.8):

217

- For bolts rigidly cast in, between centers of bolts: 31 = 10 mm inany direction.- For bolts set in sleeves. between centers of sleeves: 31 = 20mm in any direction.

1331 s 15 mm for L s 30 m.1331 s 15 + 0.25 (L - 30) mm for L > 30 m (maximum 50 mm).

Dimensional Tolerances

2- The distance between two adjacent columns, measured at thebase of the steel structure, shall not exceed the value 32 = ± 10 mmof the nominal distance (Fig.12.8).

Deviation amax Fig.Positional deviation of e, 5 mm in any direction. 12.4adjacent end plates of

I oirders..Length of prefabricated AI, + 0.0 12.5components to be fllted Ahc

-5 mm.between other comoonentsMaximum bow of web for fw Least panel dimension 12.3plate girders with 1115 Fordllw < 150. andintermediate stiffeners Least panel dimension 12.6(depth of web d. thickness 190 For dllw ~ 150.of web t w) .

Flanges of plate girders. A A < C/250 < 6 mm. 12.7Unevenness of plates in 1 mm over a gaugethe case of contact bearing length of 300 rnm,surfaces.

216Dimensional Tolerances

12.7 PERMISSIBLE DEVIATIONS OF ERECTED STRUCTURES

Deviation amax Fia.Overall dimensions of the LAh ± 20 mm for L,; 30 m. 12.9building .. or ± 20 + 0.25 (L - 30) mm.

LAL For L > 30 m (maximum50 rnrn),

Level of top of floor slab. Ah ±5mm. 12.5Floor bearinu on column.Inclination of column in a Vh 0.003 h,. 12.10multi-storey building; h, = Floor height undermaximum deviation for consideration.the vertical line betweenadiacent floor slabs.Inclination of column in a v, . 0.0035( L h, )3/(0+2) 12.11multi-storey building;maximum deviation for n = Number of fioors .the vertical line through .

the intended location ofthe column base.Inclination of column in a Vhl 0.0035 h 12.12single-storey residentialbuilding; h = Single-storey floormaximum deviation for height.the vertical line.Inclination of column of a Vnp1 Individualportal frame in an Vhpl or Vhp2'; 0.010 h

12.13

industrial building, (not or orsupporting crane gantry), Vhp2 Mean = 12.14maximum deviation for

(VhPl + VhP2)< 0 002 hthe vertical line. 2 .

Unintentionai eccentricity ec 5mm. 12.15of oirder bearino.Distance between AI, ± 15 mm. 12.9adjacent steel columns atanvlevel.

Deviation lim", Fig.

Distance between Alt ±20mm. 12.5

adjacent steel girders atany level.Positional deviation of a e2 5 mm in any direction. 12.16

column base in relation tothe column axis throughthe head of the columnbelow (applied also in thecase of indirect loadtransmission).Deviation in level of Ahc +O.Omm. 12.17

bearing surfaces on steel -10 mm.columns (crane girderteven.Positional deviation of e, ±5mm. 12.18

bearing surfaces.

: '

Dimensional Tolerances 218Dimensional Tolerances 219

Figure (12.3) Deviations in Welded Girders

1Detail(1)

Detail(i)

Figure (12.1) Inclination and Deflections of Columns

c'f ~f-,i 1 ( 1 11

Detail 2

--I----'.O~/ ~---+-I •

Figure (12.4) Deviation in Connecting Pieces~bl

0'10;1(1)

I II"11=~

Figure (12.2) Deflection of Girders

Dimensional Tolerances 220CWnenswnafTolenances 221

I,

t.t6h 1hi Level of Top of Fleer Slab ~I

l,tM, Floor Bearing on Column

6

I Tr- 6h Deviation From ~

I,l,tM, t,:+6h 1:r6h) he Column Length With ~I' ,

Intermediate Componenls

';he Deviation From he

O'~It Distance Between Adjac.entGirders

:\I, Deviation From it

Figure (12.7) Deviation in Flanges of Welded Plate Girders

Figure (12.5) Deviation in Height and Length

Iu

1d

lfj ± 02 , I, ,

Figure (12.6) Welded Plate Girder Figure (12.8) Deviation in Length at Base of Steel Structure(Plan)

Dimensional Tolerances 222 Dimensional Tolerances223

Figure (12.9) Deviation in Length (Vertical Section)

-

Figure (12.11) Inclination of Column in a Multi-Storey Building

it, .1===-,

h

, /(/ /

I

Figure (12.12) Inclination of Column in a Single-Storey Building

Figure (12.10) Inclination of Column in a MUlti-Storey Building

Dimensional Tolerances 224 Dimensional Tolerances 225

Figure (12.13) Inclination of Column in a Portal Frame

Figure (12.14) Inclination of Column in a Portal Frame

Figure (12.15) Eccentricity of Girder Bearing

}[;fel.

2

'IJf--

ITFigure (12.16) Deviations in Columns Splices

Dimensional Tolerances 226Dimensional Tolerances 227

Figure (12.17) Deviations inLevel of Bearing Surfaces

IFigure (12.18) Deviation in

Position of Bearing Surfaces

CHAPTER 13

FABRICATION ,ERECTION AND FINISHING WORKS

13.1 GENERAL PRDVISIONS

13.1.1 Scope

Unless otherwise specified in the Contract Documents, the tradepractices that are defined in this Code shall govern the fabricationand erection of steel structures (temporary and permenant).

13.1.2 Responsibility for Design

13.1.2.1 When the Employe(s Designated Representative for Design(hereinafter called EDRD) provides the design, design drawings andspecifications, the Fabricator and/or the Erector shall be responsiblefor checking suitability, adequacy and building-code conformance ofthe design. The Fabricator and/or the Erector shall give promptnotice to the the employer and EDRD of any error, omission, fault orother defects in the design of or design drawings or specification.

13.1.2.2 When the Employer enters into a direct contract with theFabricator to both design and fabricate an entire completed steelstructure, the Fabricator shall be solely responsible for the SUitability,adequacy and building-code conformance of the structural steeldesign. The Employer shall be responsible for the SUitability,adequacy and building-code conformance of the non-structural steelarrangement.

13.1.3 Patents and Copyrights

The entity or entities that are responsible for the specificationand/or selection of proprietary structural designs shall secure allintellectual properly rights necessary for the use of those designs.

Dimensional TOlerances 228 Fabrication,ErectionAndFinishing Works 229

13.1.4 Existing Structures

Unless specifically otherwise specified in the tender documentsthe scope of works to be carried out by the Fabricator and lor Erectorshall Include:

13.1.4.1 Demolition and shoring of any part of an existing structure;

13.1.4.2 Protection of existing structures and its contents andequipment, So as to prevent damage from erection works.

13.1.4.3 Surveying or field dimensioning of relevantstructures; and existing

13.1.4.4 Abatement or removal of HazardousMaterials,

Such works shall be performed in a timely manner so as not toInterfere with or delay the Fabrication and/or the Erection works,

13.2 SHOP FABRICATION AND DEUVERY

All workmanship shall be of first classquality in every respect Thegreatest accuracy shall be observed to ensure that all parts ';i11 fitproperly togrther on erection,

13.2.1 Identification Of Material

13.2.1.1 Material ordered to special requirements shall be marked bthe Supplier pnor to delivery to the Fabricator's shop or other point o~use,

Material that is ordered to special requirements, but not so marked bythe Supplier, shall not be used until:

a~ its identification is established by means of testing in accordanceWith the applicable Egyptian standard SpeCifications; and

b- a Fabricator's identification mark, as described in Clause 1321 2and 13,2,1.3, has been applied, .. ,

13.2.1.2 During fabrication, up to the point of assembling members,each piece of material that is ordered to special requirements shallcarry a Fabricator's identification mark or an original Supplier'sidentification mark. The Fabricator's identification mark shall be inaccordance with the Fabricator's established identification system,which shall be made available prior to the start of fabrication for theEmployer's Designated Representative for Construction (hereinaftercalled EDRC), the Building-Code AuthOrity and the Inspector.

'13.2.1.3 Parts that are made of material that is ordered to specialrequirements shall not be given the same assembling or erectionmark as members made of other material, even if they are of identicaldimensions and detail.

13.2.2 Preparation of Material

13.2.2.1 Thermal cutting of structural steel by hand-qulded ormechanically guided means is permitted.

13.2.2.2 Surfaces that are specified as "Finished" in the ContractDocuments shall have a suitable roughness height value. The use ofany fabricating technique that produces such a finish is permitted.

13.2.3 Fitting and Fastening

13.2.3.1 Projecting elements of Connection materials need not bestraightened in the connecting plane.

13.2.3.2 Backing bars and runoff tabs shall be used as required toproduce sound welds. The Fabricator or Erector need not removebacking bars or runoff tabs unless such removal is specified in theContract Documents. When the removal of backing bars is specifiedin the Contract Documents, such removal shall meet therequirements in the relevant welding specification. In such cases,hand flame-cutting close to the edge of the finished member with nofurther finishing is permitted, unless other finishing is specified in theContract Documents,

Fabrication,ErectionAnd Finishing WOrks

230 Fabrication, ErectionIVld Flnishi1!9 Works 231

13.2.4 Fabrication Tolerances

The tolerances on structural steel tabncauon shall be inaccordanceWith the requirements in Chapter 12 of this Code.

13.2.5 Shop Cleaning and Painting

ahPP~~~~~sr~~~:~ep~fn~c:~~~,i~~:~~~Zns::e~~e~i~~~:~ocreoatt ~fsipped from the works. I IS

Surfaces not in contact but in 'blshall be painted three co~ts Th:~~~sl e atft~ assembly or erection,

painted. Field contact sUrf~ces shaIlPr~~~i:e :~~~~e~a~a~r"0tb~except main splices for chords of trusses a ' . pam ,involving multiple thickness of ten I h no large girder spliceswould make e cti " rna ena were a shop coat of paintthe h re Ion difficult. Field contact surfaces not painted with

s op coat shall be given a coat of a dprotective coating if it is expected that t~~~v='11 I~cquer or otherperiod of exposure before erection. I e a prolonged

pai~~~aces, which will be in contact with concrete, shall not be

:~~~E~~:~}e~~~~:~l~i~t~~~~i~:~':~~"i~~~~~~i~~~i~~~o~~fterShoP welding is finishe~. Ste~: ~~i~~lIi~~~~~efi~~::I~te~ p~inltle given one coat of boiled tinseed oll th ,s a

coating after shop welding and shop tb or °t' er approved protectivea rica Ion IS completed.

be ~~:~C:~eo~~~~fa~~i~:.eel castings, either milled or finished, shall

fini;;;~~ ~~~ae:e~e~~~~ ~~ :~:~~g joints and base.plates, machine-accepted, with a hot mixture as soon as practicable after beingcoating, before removal from t~:~~~~.Iead tallow or other approved

Erection marks for field indication of members and weight marksshall be painted upon surface areas previously painted with the shopcoat. Material shall not be ioaded for shipment untill it is throughlydl'i, and in any case not less than 24 hours after the paint has been

applied.Structural steel that does not require shop paint shall be cleaned

from any oil or grease with solvent cleaners. and of dirt and otherforeign material by sweeping with a fiber brush or other suitablemeans. For"structural steel that is required to be shop painted, therequirements in Clauses 13.2.5.1 through 13.2.5.4 shall apply.

13.2.5.1 The Fabricator is not responsibie for deterioration of theshop coat that may result from exposure to exceptional atmosphericor corrosive conditions that are more severe than the normal ones,

13.2.5.2 Unless otherwise specified in the Contract Documents, theFabricator shall, as a minimum, hand clean the structural steel ofloose rust, loose mill scale, dirt and other foreign mailers, prior topainting, by means of wire brushing or by other methods selected bythe Fabricator. If the Fabricator's workmanship on surfacepreparation is to be inspected by the Inspector, such inspection shallbe performed in a timely manner prior to the application of the shop

coat.

13.2.5.3 Unless otherwise specified in the Contract Documents, paintshall be applied by brushing, spraying, rolling, flow coating, dipping orother suitable means, at the election of the Fabricator. When theterm "shop coat", "shop paint" or other equivalent term is usedwith nopaint system specified, the Fabricator's standard shop paint shall beapplied to a minimum dry-film thicknessof one coat [40 micron].

13.2.5.4 Touch-up of abrasions caused by handling after paintingshall be the responsibility of the Contractor that performs fieldpainting.

Fabrication,ErectionAndFinishing WorKs 232

Fabrication,ErectionAndFinishing Works 233

13.3 ERECTION

13.2.7.5 If material anrives at its destination in damaged condition,the receiving entity shall promptly notify the Fabnc:'tor and cam~rprior to unloading the material, or promptiy upon discovery pnor 0

erection.

13.3.1 Method of Erection

Fabricated Structural Steel shall be erected using methods and asequence that will permit efficient and economical performance oferection and that is consistent with the requirements of the ContractDocum~nts. If the EDRC wishes to prescribe or control.the methodand/or sequence of erection, or specifies that certain memberscannot be erected in their normal sequence, the required method andsequence has to be specified in the .contract Documents. If theEDRC contracts separately for fabrication services and for erectionservices, the EDRC shall coordinate between contractors.

13.3.2 Job-5ite Conditions

The EDRC shall provide and maintain the following for theFabricator and the Erector:

a- Adequate access roads into and through the job site for the safedelivery and movement of the material to be erected and of derncks,cranes, trucks and other necessary equipment.

b- A firm, properly graded, drained, convenie~t and adequate space atthe job site for the operation of the Erector5 equipment. free fromoverhead obstructions, such as power lines, telephone lines or Similarconditions; and

c- Adequate storage space, when the structure does not occupy thefull available job site, to enable the Fabricator and/or the. Erector tooperate a practical speed. Otherwise, the EDRC shall inform the

23SFabrication,ErectionAnd FinishingWorks

13.2.7.4 Unless otherwise specified in the Conlract Documents, andSUbject to the approved Shop and Erection Drawings, the Fabricatorshall limit the number of fieid splices to that consistent with minimumproject cost. .Fabrication,ErectionAnd FinishingWorks 234

13.2.7.3 If any shortage is claimed relative to the quantities ofmaterials that are shown in the shipping statements, the EDRC or theErector shall promptly notify the Fabricator so that the claim can beinvestigated.

13.2.6 Marking and Shipping of Materials

13.2.6.1 Unless otherwise specified in the Contract Documents,erection marks shall be applied to the structural steel members bypainting or other suitable means.

13.2.6.2 Bolt assemblies and loose bolts, nuts and washers shall beshipped in separate closed containers according to length anddiameter, as applicable. Pins and other small parts and packages ofbolts, nuts and washers shall be shipped in boxes, crates, kegs orbarrels. A list and description of the material shall appear on theoutside of each closed container.

13.2.7 Delivei y of Materials

13.2.7.1 Fabricated structural steel shall be delivered in a sequencethat will permit efficient and economical fabrication and erection, andthat is consistent with the requirements of the Contract Documents. Ifthe Employer or EDRC wishes to prescribe or control the sequence ofdelivery of materials, that entity shall specify the required sequence inthe Contract Documents. If the EDRC contracts separately fordelivery and for erection, the EDRC shall coordinate betweencontractors.

13.2.7.2 Anchor Rods, washers, nuts and other anchorage or grillagematerials that are to be built into concrete or masonry shall beshipped so that they will be available when needed. The EDRC shallallow the Fabricator sufficient time to fabricate and ship suchmaterials before they are needed.

oq

236

13.3.5.4 All work that is performed by the EDRC shall be completedso as not to delay or interfere with the work of the Fabricator and/orthe Erector.

The EDRC shall conduct a survey of the as-built loeations of AnchorRods, foundation bolts and other embedded items, and shall verifythat all items covered in Clause 13.3.5.1 meet the correspondingtolerances. When corrective action is necessary, the EDRC shallobtain the guidance and approval of the EDRD.

13.3.7 Grouting

Grouting shall be the responsibility of the Erector. Leveling platesand loose base and bearing plates shall be promptly grouted afterthey are set, checked for line and grade, and approved by EDRC.Columns with attached base plates, beams with attached bearingplates and other similar members w~h attached bearing devices thatare temporarily supported on leveling nuts and washers, shims orother similar leveling devioes, shall be promptly grouted after theStructural Steel frame or portion thereof has been plumbed.

237Fabrication,ErectionAnd FinishingWorks

13.3.6 Installation of Bearing Devices

All leveling plates, leveling nuts and washers and loose base andbearing plates that can be handled without a derrick or crane are setto line and grade by the EDRC. Loose base and bearing plates thatrequire handling with a derrick or crane shall be set by the Erector tolines and grades established by the EDRC. The Fabricator shallclearly scribe loose base and bearing plates w~h lines or othersuitable marks to facilitate proper alignment. Promptly after thesetting of Bearing Devices, the EDRC shall check them for line andgrade. The variation in elevation relative to the established grade forall Bearing Devices shall be equal to or less than plus or minus 3 mm.The final location of Bearing Devices shall be the responsibility of theErector.

13.3.4 BUilding Lines and Bench Marks

The EDRC shall be responsibl f .bUilding lines and bench-marks at e or the accurate location ofErector with a plan that can' the Job site and shall fumish theestablish offset bUilding lin~~:Sn~lIr:~~h Infor~ation. The EDRC shallfor the Erector's usage in the .. renee e evations at each levelClause 13.3.13), if any. positioning of adjustable Items (see

13.3.5 Installation of Anchor B I .embedded Items 0 Is, Foundation Bolts and other

13.3.5.1 Anchor rods found f bshall be set by th~ EDR~ Ion olts and other embedded itemsEmbedment Drawin Th . In accordance with an approvedthe dimensions sh;'~n i~ ~~~atlon In location of these items frommentioned in Clause 12.6 Embedment Drawings shall be as

13.3.5.2 Unless otherwise specified .Anchor Rods shall be set with their In the Contract Documents,the theoretical bearing surface. longitudinal axis perpendicuiar to

Fabricator and the Erector of the actual" ..special delivery requirements in th t d Job-site conditions and/or

e en er documents.

13.3.3 Foundations, Piers and Abutments

The location, strength and suitabltfoundations, piers and abutments shal: ';e ~~' and access to, allEDRC. e responsibility of the

13.3.5.3 Embedded items and c . .the work of other trades but th onnecnon matenals that are part oflocated and set by th'e ED~~Will receive Structural Steel, shall beEmbedment Drawing. The van . I". accordance with an approvedlimited to a magnitUde that I'S ration In localion of these items shall be

. . consistent with th t Ispecified In Clause 13 3 5 1 f th . e a erances that are. .. or e erection of the Structural Steel.

Fabrication,ErecDonAnd Pinishing Works

---------------------------.-------------------~- ~-

13.3.8 Field Connection Material

13.3.8.1 The Fabricator shall provide field connection details that areconsistentwith the requirements of the Contract Documents and thatwill result in economical fabrication and erection.

13.3.8.2 When the Fabricator is responsible for erecting theStructural Steel, the Fabricator shall furnish all materials that arerequired for both temporary and permanent Connection of thecomponent parts of the Structural Steel frame.

13.3.8.3 When the erection of the Structural Steel is not performedby the Fabricator, the Fabricator shall furnish the following fieldConnection material:

a- Bolts, nuts and washers of the required grade, type and size insufficient quantity for all Structural Steel-to-Structural Steel fieldconnections that are to be pemnanently bolted, including an extra 2percent of each bolt size (diameter and length);

b- Shims that are shown as necessary for make-up of permanent.structural steel-to-structural steel connections; and,

c- Backing bars and run-off tabs that are required for field welding.

13.3.8.4 The Erector shall furnish all welding electrodes. fit-up boltsand drift pins used for the erection of the Structural Steel.

13.3.9 Loose Material

Unless otherwise specified in the Contract Documents, looseStructurai Steel items that are not connected to the Structural Steelframe shall be set by the Erector.

13.3.10 Temporary Support of Structural Steel Frames

13.3.10.1 The EDRD shall identify the following in the ContractDocuments;

a- The lateral-load-resisting system and connecting diaphragmelements tljat provide for lateral strength and stability in thecompleted structure; and,

b- Any special erection conditions or other considerations that arerequired by the design concept, such as the use of shores, Jacks orloads that must be adjusted as erection progressesto set or maintaincamber, positionwithin specified tolerances or pre-stress.

13.3.10.2 The EDRD shall indicate to the Erector , in the tenderdocuments the installation schedule for non-Structural Steelelements 'of the lateral-load-resisting system and connectingdiaphragm elements identified in the Contract Documents.

13.3.10.3 Based upon the infomnation provided in accordance withClauses 13.3.10.1 and 13.3.10.2, the Erector shall detemnine, furnishand install all temporary supports, such as temporary guys, beams,falsewor1<, cribbing or other elements required for the erectionoperation. These temporary supports shall be sufficient to secure thebare Structural Steel framing or any portion thereof against loads thatare likely to be encountered during erection, including those due towind and those that result from erection operations.

13.3.10.4 All temporary supports that are required for the erectionoperation and furnished and installed by the Erector shall remain theproperty of the Erector and shall not be modified, moved or removedwithout the consent of the Erector. Temporary supports provided bythe Erector shall remain in place unlil the portion of the StructuralSteel frame that they brace is complete and the lateral-load-resistingsystem and connecting diaphragm elements identified by the EDRDin accordance with Clause 13.3.10.1 are mstalled. Temporarysupports that are required to be left in place after the completion ofStructural Steel erection shall be removed when no longer needed bythe EDRC and returnedto the Erector.

Fabrication,ErectionAndFinishing Works 238 Fabricafion,Ereclion

AndFinishing Works 239

13.3.11 Safety Protection

13.3.11.1 The Erector shall provide floor coverings, handrails.walkways and other safety protection for the Erectors personnel asrequired by iaw and applicable safety regulations. Unless otherwisespecified in the Contract Documents, the Erector is permitted toremove such safety protection from areas where the erectionoperations are completed and approved by EDRC.

13.3.11.2 When safety protection provided by the Er<lctoris left in anarea for the. use of other trades after the Structural Steei erectionactivity is completed, the EDRC shall:

a- Indemnify the Fabricator and/or the Erector from damages thatmay be incurred from the use of this protection by other trades;

b- Ensure that this protection is adequate for use by other affectedtrades;

c- Ensure that this protection complies with applicable safetyregulations when being used by other trades; and

d- Instruct the Fabricator and/or the Erector remove this protectionwhen it is no longer required.

13.3.11.3 Safety protection for other trades that are not under thedirect empioyment of the Erector shall be the respcnsitnhty of theEDRC.

13.3.11.4 When permanent steel decking is used for protectiveflooring and is installed by the EDRC all such work shall bescheduled and performed in a timely manner so as not to interferewith or delay the work otthe Fabricator or the Erector

13.3.11.5 Unless the interaction and safety of activities of otherssuch as construction by others or the storage of materials that belongto others, are coordinated with the work of the Erector by the EDRC,such activities shall not be permitted until the erection of the

Structurai Steel frame or portion thereof is completed by the Erectorand accepted by the EDRC.

13.3.12 Structural Steel Frame Tolerances

The accumulation of the mill tolerances and fabrication tolerancesshall not cause the erection tolerances to be exceeded.

13.3.13 Erection Tolerances

Erectionjolerances shall be defined relative to member workingpoints and working lines, which shall be defined as follows:

a- For members other than horizontal members, the member workpoint shall be the actual center of the member at each end of theshipping piece.

b- For horizontal members, the working point shall be the actualcenterline of the top flange or top surface at each end.

c- The member working line shall be the straight line that connectsthe member working points.

The substitution of other working points is permitted for ease ofreference, provided they are based upon the above definitions. Thetolerances on Structural Steel erection shall be in accordance withthe requirements in Chapter 12 of this Code.

13.3.14 Correction of Errors

The correction of minor misfits by moderate amounts of reaming.grinding, welding or cutting, and the drawing of elements into line withdrift pins, shall be considered to be normal erection operations. Errorsthat cannot be corrected using the foregoing means, or that requiremajor changes in member or connection configuration, shall bepromptly reported to the EDRD and EDRC and the Fabricator by theErector, to enable the responsible entity to either correct the error orapprove the most efficient and economical method of correction to beused by others.

n

Fabn"cation,ErectionAnd Finishing Works 240 Fabrication,Erecffon

AndFinishing Works 241

13.3.15 Cuts, Alterations and Holes for other Trades

Neither the Fabricator nor the Erector shall cut, drill or otherwisealter their work, nor the work of other trades, to accommodate othertrades, unless such work is cleariy specified in the ContractDocuments. When such work is so specified, the EDRD and EDRCshall furnish complete information as to materials, size, location andnumber of alterations in a timely manner so as not to delay thepreparation of Shop and Erection Drawings.

13.3.16 Handling and Storage

The Erector shall take reasonable care in the proper handling andstorage of the Structural Steei during erection operations to avoid theaccumulation of excess dirt and foreign matter. The Erector shall beresponsible for the removal from the Structural Steel of dust, dirt orother foreign matter that may accumuiate during erection as the resultof job-site conditions or exposure of the elements.

13.3.17 Field Painting

The Erector is responsible to paint field bolt heads and nuts orfield welds, nor to touch up abrasions of the shop coat, norlo performany other fieid painting.

13.3.18 Final Cleaning Up

Upon the completion of erection and before final acceptance, theErector shall remove all of the Erector's talsework, rubbish andtemporary buildings.

13.4 QUALITY ASSURANCE

13.4.1.2 The Erector shall maintain a quality assurance program toensure' that the work is performed in accordance with therequirements of this Code and the Contract Documents. The Erectorshall bear the costs of performing the erection of the Structural Steel,and shall provide all necessary equipment,material, personnel andmanagement for the scope, magnitude and required quality of eachproject .

13.4.2 Inspection of Mill Material

Certified mill test reports shall constitute sufficient evidence thatthe mill product satisfies material order requirements. The Fabricatorshall make a visual inspection of material that is received from themill, but need not perform any material tests unless the EDRDspecifies in the Contract Documents that additional testing is to beperformed.

13.4.3 Non-Destructive Testing

When non-destructive testing is required, the process, extent,technique and standards of acceptance shall be clearly specified inthe Contract Documents.

13.4.4 Surface Preparation and Shop Painting Inspection

Inspection of surface preparation and shop painting shall beplanned for the acceptance of each operation as the Fabricatorcompletes it. Inspection of the paint system, including material andthickness, shall be made promptly upon completion of the paintapplication. When wet-film thickness is to be inspected, it shall bemeasureddUringthe application.

13.4.1 General

13.4.1.1 The Fabricator shall maintain a quality assuranceprogram toensure that the work is performed in accordance with therequirements of this Code and the Contract Documents

243Fabrication,ErectionAnd Finishing Works 242

13.4.5 Independent Inspection

When inspection by personnel other than those of the Fabricatorand/or Erector is specified in the Contract Documents, therequirements in Clauses 13.4.5.1 through 13.4.5.6 below shall bemet.Fabtication,ErectionAnd FinishingWorks

13.4.5.1 The Fabricatgr and/or the Erector shall provide the Inspectorwith access to all places where the work is being performed. Aminimum of 24 hours notification shall be given prior to thecommencement of work.

13.4.5.2 Inspection of shop work by the Inspector shall be performedin the Fabricator's shop to the fullest extent possible. Suchinspections shall be timely, in-sequence and performed in such amanner as will not disrupt fabrication operations and will permit therepair of non-conforming work prior to any required painting while thematerial is still in-process in the fabrication shop.

13.4.5.3 Inspection of fieid work shall be promptly completed withoutdelaying the progress or correction of the work.

13.4.5.4 Rejection of material or workmanship that is not inconformance with the Contract Documents shall be permitted at anytime durmq the progressof the work.

13.4.5.5 The Fabricator and/or the Erector shall be informed ofdeficiencies that are noted by the Inspector promptly after theinspection. Copies of all reports prepared by the Inspector shall bepromptly given to the Fabricator and/or the Erector. The necessarycorrective work shall be performed in a timely manner.

13.4.5.6 The Inspector shall not suggest, direct, or approve theFabricator and/or Erector to deviate from the Contract Documents orthe approved Shop and Erection Drawings, or approve suchdeviation, without the written approval of the EDRD and EDRC.

13.5 CONTRACTS

13.5.1 Types of Contracts

13.5.1.1 For contracts that stipulate a lump sum price, the work thatis required to be performed by the Fabricator and/or the Erector shallbe completely defined in the Contract Documents.

13.5.1.2 For contracts that stipulate a price per ton, the scope ofwork that is required to be performed by the Fabricator and/or theErector, the type of materials, the character of fabrication and theconditions of erection shall be based upon the Contract Documents,which shall be representative of the work to be performed.

13.5.1.3 For contracts that stipulate a price per item, the work that isrequired to be performed by the Fabricator and/or the Erector shall bebased upon the quantity and the character of the items that aredescribed in the Contract Documents.

13.5.1.4 For contracts that stipulate unit prices for various categoriesof Structural Steel, the scope of work required to be performed by theFabricator and the Erector shall be based upon the quantity,character and complexity of the items in each category as describedin the Contract Documents, and shall also be representative of thework to be performed in each category.

13.5.2 Calculation of Weights

Unless otherwise specified in the contract, for contracts stipulatinga price per ton for fabricated Structural Steel that is delivered and/orerected, the quantities of materials for payment shall be determinedby the calculation of the gross weight of materials as shown in theShop Drawings.

13.5.2.1 The unit weight of steel shall be taken as 7850 kg/m3. The

unit weight of other materials shall be in accordance with themanufacturer's published data for the specific product.

Fabrication,ErectionAndFinishing Works 244

Fabrication,ErectionAndFinishing Worlcs 245

13.5.2.2· The weights of Standard Structural shapes, plates and barsshall be calculated on the basis of Shop Drawings' that show theactual quantities and dimensions of material to be fabricated, asfollows:

a- The weights of all Standard Structural shapes shall be calculatedusing the nominal weight per meter and the detailed overall length.

b- The weights of plates and bars shall be calculated using thedetailed overall rectangular dimensions.

c- When parts can be economically cut in muitiples from material oflarger dimensions, the weight shall be calculated on the basis of thetheoretical rectangular dimensions of the material from which theparts are cut.

d- When parts are cut from Standard Structural shapes, leaving anon-standard section that Is not useable on the same contract, theweight shall be calculated using the nominal weight per meter and thedetailed overall length of the Standard Structural shapes from whichthe parts are cut.

e- Deductions shall not be made for material that is removed for cuts,copes, clips, blocks, drilling, punching, boring, slot milling, planing orweld joint preparation.

1

13.5.4 Contract Price Adjustment

13.5.4.1 When the scope of wor1l and responsibilities of theFabricator and/or the Erector are changed from those previouslyestablished in the Contract Documents, an appropriate modificationof the contract price shall be made. In computing the contract priceadjustment, the Fabricator and the Erector shall consider the quantityof work that-is addedor deleted, the modifications in the character ofthe work and the timeliness of the change with respect to the statusof material ordering,detailing, fabrication and erection operations.

13.5.4.2 Requests for contract price adjustments shall be presentedby the Fabricator and/or the Erector in a timely manner and shall beaccompanied by a description of the change that is sufficient topermit evaluation and timely approval by the Employer.

13.5.4.3 Price-per-ton and price-per-item contracts shall provide foradditions or deletions to the quantity of work that are made prior tothe time the work Is released for construction. When changes aremade to the character of the work at any time, or when additionsand/or deletions are made to the quantity of the work after it isreleased for detailing, fabrication or erection, the contract price shallbe equitably adjusted.

248

13.5.5 Scheduling

Design Drawings will be released for construction, if such DesignDrawingsare not available at the time of bidding, and/or when the jobsite, foundations, piers and abutments will be ready, free fromobstructions and accessible to the Erector, so that erection can startat the designated time and continue without interference or delaycaused by the EDRC or other trades.

13.5.5.2 The Fabricator and/or the Erector shall advise theEmployer'S EDRC and EDRD, in a timely manner, of the effect anyrevision has on the contract schedule.

13.5.2.3 The weights of shop or field weld metal and protectivecoatings shall not be included in the calculated weight for thepurposesof payment.

13.5.3 Revisions to the Contract Documents

Revisions to the Contract Documents shall be confirmed byvariation or change order or extra work order, Unless otherwisenoted, the issuance of a revision to the Contract Documents shallconstitute authorization by the Employer that the revision is releasedfor construction. The contract price and schedule shall be adjusted inaccordance with Clauses 5.4 and 5.5.FabricaDon,ErectionAndFinishing Works

Fabrication,ErectionAndFinishing Works 247

---------------~~l

13.5.5.3 If the fabrication or erection is significantly delayed due torevisions of the requirements of the contract. or for other reasonsthat are the responsibility of others, the Fabricator and/or Erectorshall be compensated for the additional time and/or costs incurred (ifany).

13.5.6 Terms of Payment

Terms of payment for the contract shall be as stated in theContract Documents.

CHAPTER 14

INSPECTION AND MAINTENANCE OF STEEL BRIDGES

14.1 GENERAL

Steel Bridges are SUbject to gradual deterioration due tocorrosion, mechanical wear, impact, and fatigue damage frommoving loads, that require periodic maintenance throughout theirservice life. .

The damage likely to get worse or to expose the security of thestructure to danger, should be repaired as quickly as possible in allcases.

14.2 INSPECTION

The inspection of steel bridges may be classified as periodicinspection and special or detailed inspection.

14.2.1 Periodic Inspection

This kind of inspection should be made at frequent, scheduledintervals depending on the condition, age of the bridge, and type oftraffic. Generally this inspection is made annually or every other yearand covers the following points:

a- General condition of paint on the entire steel structure.

b- Condition of the parts of the frame wort<. with which theconstruction design allows water to rest in contact for prolongedperiods or parts which may undergo the aggressive action of outsideagents as smok~ of trains.

e- The state 'Of rivets, bolts, welds in floor beams' connections, andalso those in splices of main girders or connecting web members toupper and lower chord member in trusses.

Fabrication,ErecfionAnd Finr.shing Works 248

d- Condilion of the gusset plates especially in old bridges whereInspection, andMaintenance 24901SteelBridges

pitches and edge distances of rivets may be found to exceedallowable maximum values.

e- State of end components of the bridge in contact with theabutments or supported on piers causing destruction of these walls orcomponents directly supported on piers.

f- Condition of bearings as well as the components of the machineryof movable bridges.

g_State of the retaining walls and piers, and their foundations.

h- State of the track especially its aiignment and location withreference to the steel structure at ends and at centre of each span.

i- Condition of the deck concerning:

1 - guard rails.2 - side walks and railings.3 - ballast bedding and its depth.4 - waterproofing.

14.2.2 Special or Detailed Inspection

Steel bridges shall undergo detailed inspection at least onceevery 4-6 years. This inspectionshall cover the following points:

a- Location and number of rivets and i,.'"",',, that are loose and ofrivets that have badly corroded heads, paying special attention tofloor connections.

noting exact location and extent of such action. Measurement ofremaining section if members are badly corroded and paYingattention to loss of metal in girders, beam flanges, webs, as well asparts of lateral bracing system.

e- Check of piers and abutment levels, especially for bridgescrossing rivers.

f- Permanent deflection shall be measured for bridge decks morethan 15.0 m span, and compared with previous values to ensure thatthere is no creep.

14.2.3 Inspection Sketch for Identification of Members

Typical sketches are to be prepared by inspector to show correctidentity and location of parts or members described in theirinspection report. Photographs shall be used to show criticalconditions and to amplify the value of the report.

14.2.4 Files of Bridges

There must be a flIe for each bridge containing the following:

1- Type and origin of materials and tests carried out beforeconstruction.

2- Type of foundation and soil investigation report.

3- Detailed as built drawings of all parts of the bridge.

4- The calculation notes.

b- Welds on lateral bracing and cross frames, stiffeners and otherwelded details must be examined.

c- State of movable bearings and the clearance between expansionends, sub-structures or adjoining spans. Special care must be givento investigate if there is any apparent movement (rotation,displacement,...) of the sub-structures.

d- Condition of membersInspection, andMaintenanceof Steel Bridges

as to loss of section due to corrosion,250

5- The priced bill of quantities used.

6- Results of tests and comparison with,theoretical calculations.

7- Possible incidencestaking place during construction.

8- Maintenance carried out especially dates when the bridge wasrepaired or strengthened.Inspection, andMaintenance 251orSteel Bridges

9- Repairs or alterations made during services.

10-Reports of inspections carried out.

11- Photographic documents on the construction phases as those,which may concern different defects or damage.

14.3 MAINTENANCE OF STEEL BRIDGES

14.3.1 Maintenance of Structural Elements

14.3.1.1 Normal maintenance must include periodical cleaning of allexposed surfaces by compressed air.

14.3.1.2 Parts which are exposed to direct attack by smoke or theprojection of aggressive products as salts. solvents.. etc., should beprotected.

14.3.1.3 Holes or cracks in the substructure can be maintained byappropriate grouting or proper use of epoxy or epoxy mortar.

14.3.1.4 Scouring in river bed must be stopped. Special measures ofriver treatment and requlation might be necessary.

14.3.1.5 It is necessary to ensure that neither water can exist onsurface of the bridge nor be allowed to accumulate in any member ofthe structure. Drainage holes with reasonable diameters must beprovided to this effect.

14.3.1.6 Painting

a- For structures not greatly exposed to corrosion, the life of wellapplied paint is at least (8-10) years. Intermediate maintenanceoperations may be resorted to, for paris of the structure which areseverely exposed to rust or for which this period would be harmful.

relevant Egyptian Standard Specification.

e- Structures where paint is wom off before the 8-10 years period,shall undergo special inspections to decide if the time between twosuccessive general painting operations should be reduced or if itwouid be necessary to apply special paint.

d- The bearing areas of the stringers for wooden sleepers should berepainted every time the wooden parts are replaced and every timethe structure is. repainted. For this purpose bituminous paints givebest resuits.

14.3.1.7 Riveting and Bolting

Loose rivets are detected by the finger and hammer test. Veryloose rivets are recognised by the visible ring of rust they havearound their heads. Loose rivets must be replaced by high-strengthbolts as these give stronger connections. If there are some looserivets in a splice, it is better to replace all the rivets in the splice bynew high strength bolts to get a horroqeneous splice. After the finaltightening of the bolts, they mu-. be painted by the usual paint.During the detailed inspectior. of bridges with high-strength boltconnections, the torque of the tightening of these bolts should bechecked by a calibrated wrench.

14.3.1.8 Play in the Assembled Units

The increase of the traffic loads leads to higher stresses in rivetsof old bridges, as, they have often badly reamed holes or badly filledholes. Under impact, these holes take an oval shape and theconnected parts slide in the direction of their own stress, developinga sort of play.

These faults should be discovered at an earty stage as theyappear during the running of traffic, and may often need thereplacement of the defected parts.

b- Where the paint is to be maintained on steel surfaces, the steelshall be prepared and painted with the recommendations of the

Inspection, andMaintenanceatSteelBridges

252

14.3.1.9 Cracks in Old Bridges

It is not recommended to weld a crack in a riveted girder, since,Inspection, andMaintenance 253of SteelBridges

with time this shall cause other cracks, however welding may beused in cases where riveting or bolting is not possible. The crackedpart can be replaced by a new part or the crack can be covered witha riveted or bolted cover plate. The crack propagation may bestopped by drilling 15 mm holes at either end of tha crack. Besides,the spiice plate ends must be in low stress range areas.

14.3.1.10 Bearings

a- Sliding bearings

During periodic maintenance the sliding plate must be cleaned toeliminate all deposits or rust which might lessen their function. Forbridges 15 m span or more, the sliding bearings must be lubricated.The main girders should be well seated on the bearing plates. Anyplay should be eliminated by putting temporary steel packing of athickness corresponding to the amount of play, to provide thenecessary contact. It is also important to ensure the anchorage ofthe bridge and the maintenance of the level of the track at both ends.

The use of elastomeric bearings should be generalised instead ofthe steel bearings, as they are found to stop dislocation of bearingwith respect to abutments. Broken bearing plates must be replaced,unlessthe break isolates only a negligible part of the surface.

b- Roller bearings

During periodic maintenance all roller surfaces and their joints aswell as the bearing plates must be cleaned and lubricated. When thebridge is repainted care must be taken to prevent any deposits orprojection of paint blocking the bearings when it dries. Badly locatedrollers or rockers, which have fallen over, should be placed in theircorrect position, after lifting the bridge. The engineer should decidethe suitable time and the ambient temperature for which the rollersshould be placed in their correct mean position. If the roller bearingsare not provided with end wider discs, or strong side bars, they areliable to move sideways, and thus it is recommended to provide suchfittings.

14.3.1.11 Jacking of Bridges for Bearing Replacement

It is recommended to foresee in the initial design of steei bridgessome reservations to allow for lifting operations required to replacedamaged bearings. If, as for old bridges, jacking- up is notforeseeable, it may be necessary to add new temporary structuralelements such as: short corbels, lifting brackets or niches toaccommodate the jacks. In case the available under beams heightdoes not allow the positioning of normal jacks, flat jacks may be usedinstead. Steel bridge components may require strengthening beforethe start-up of jacking in order to prevent damage of the existingstructure. The lifting-up and bringing down into position operationsshould be carried out under continuous monitoring, follow-up andengineering supervision by qualified personnel making available tothem the appropriate equipment.

Splitting of bearing, broken rollers may result in cracks andsettlement of the superstructure. Deciding on the type of newbearings should be carefully studied considering the followingfactors: the height of old versus the new bearings, force transmissionparticularty those acting in the horizontal direction, also the stabilityof the sub structure components. Jacks should preferably rest onTeflon plates to eliminate any horizontal reactions that may induceadditional stresses in the superstructure. The cylinder capacity of thejack is to be calculated from the maximum reaction inciuding liveload and impact, if the works are performed under normal trafficconditions and only for dead loads if traffic is interrupted. Should thecalculated reactions exceed the actual values, one has to consider,for safety purpose, the highest of them both.

Inspection, andMaintenancsof SteelBridges

254Inspection, andMaintenanceofsteel Bridges

255