Pp6.Connection Design Weld

8/11/2019 Pp6.Connection Design Weld

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0O1TED CONNECTIONS

Sli%critical and bearing t'e bolted connections.

Connections should be designed to be sli%critical (here2 stress reversal$ heav' imact loads$ severe vibration

3oint sliage (ould be detrimental to the serviceabilit' of the structure

4oints that must be designed to be sli%critical include 4oints sub3ect to fatigue loading or significant load reversal.

4oints (ith oversi5ed holes or slotted holes

4oints (here (elds and bolts sharing in transmitting load

4oints in a&ial tension or combined a&ial tension and shear

0earing%t'e bolted connections can be designed for 3ointssub3ected to comression or 3oints for bracing members


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S1I6%C7ITICA1 0O1TED CONNECTION

Sli%critical bolted connections can fail in t(o (a's2 8a9 sli at theconnection: 8b9 bearing failure of the connection

Sli%critical connection must be designed to2 8a9 resist sli at load

Service II; and 8b9 resist bearing ; shear at strength limit states


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Sli%critical bolted connections can be installed (ith such a degreeof tightness large tensile forces in the bolt clam the

connected lates together

Alied Shear force resisted b' friction

Tightened

P

P

TightenedTightened

P

P

P

P

Tb

N =Tb

N =Tb

N =Tb

P

F=N

Tb

N = Tb

F=N

N = Tb

N =Tb

P

Tb

N =Tb

Tb

N =Tb

N =Tb

N =Tb

P

F=N

N =Tb

N =Tb

P

F=N

Tb

N = Tb

Tb

N = Tb

F=N

N = Tb

N =Tb

P

F=N

N = Tb

N =Tb

N = Tb

N =Tb

P


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Slip-critical connectionscan resist the shear force using friction. If the alied shear force is less than the friction that develos bet(een

the t(o surfaces$ then no sli (ill occur bet(een them

Nominal sli resistance of a bolt in a sli%critical connection

7n< =h=sNs6t

>here$ 6t< minimum re)uired bolt tension secified in Table ?=h< hole factor secified in Table ?

=s< surface condition factor secified in Table /


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@a'ing surfaces nainted clean mill scale$ and blast%cleaned surfaces (ith Class Acoating

nainted blast%cleaned surfaces (ith Class Bcoating

Bot%di galvani5ed surfaces roughened b' (ire brushing Class C

Bolt diameter

(in.)

Required Tension

(kips)

A3! A"#$

!%& '# "

3%" & 3!

%& 3# "#' !' "

'*'%& ! &$

'*'%" ' '$

'*3%& &! ''

'*'% '$3 '"&

For standard holes '.$

For o+ersi,e and short*slotted holes $.&!

For long slotted holes -ith the slot

Perpendiular to the /ore diretion

$.$

For long*slotted holes -ith the slot

Parallel to the /ore diretion

$.$

Values of Kh

Values of Pt

For 0lass A sur/ae onditions $.33

For 0lass B sur/ae onditions $.!$

For 0lass 0 sur/ae onditions $.33

Values of Ks


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S1I6%C7ITICA1 CONNECTION

Connection sub3ected to tensile force 8Tu9$ (hich reduces claming

Nominal sli resistance should be reduced b' 8?% Tu;6t9

Sli is not a catastrohic failure limit%state because sli%criticalbolted connections behave as bearing t'e connections after sli.

Sli%critical bolted connections are further designed as bearing%t'ebolted connection for the alicable factored strength limit state.


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0EA7ING CONNECTION

In a bearing%t'e connection$ bolts are subjected to shearand theconnecting ; connected lates are sub3ected to bearing stresses 2

Bolt in shear

Bearing stresses in plate


TT

T

T

Bolt in shear



Bolt in shear



TT

T

T


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0EA7ING CONNECTION

0earing t'e connection can fail in several failure modesa9Shear failure of the boltsb9E&cessive bearing deformation at the bolt holes in the connected artsc9 Edge tearing or fracture of the connected lated9Tearing or fracture of the connected late bet(een t(o bolt holese9@ailure of member being connected due to fracture or bloc+ shear or ...


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0EA7ING CONNECTION

Nominal shear resistance of a bolt

Threads e&cluded2 7n< -. Ab@ubNs

Threads included2 7n< -./ Ab@ubNs>here$ Ab< area of the bolt corresonding to the nominal diameter

@ub< ?- +si for A/" bolts (ith diameters -." through ?.- in.

@ub< ?-" +si for A/" bolts (ith diameters ?.?" through ?." in.

@ub< ?"- +si for AF- bolts.

Ns< number of shear lanes

7esistance factor for bolts in shear < s< -.-

E)uations above % valid for 3oints (ith length less than "-.- in. If the length is greater than "- in.$ then the values from the e)uations

have to be multilied b' -.


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0EA7ING CONNECTION

S6ACING 7EHI7E*ENTS *inimum sacing bet(een centers of bolts in standard holes shall not

be less than three times the diameter of the bolt

@or sealing against enetration of moisture in 3oints$ the sacing on asingle line ad3acent to the free edge shall satisf' s 8.- J .- t9 !.-

*inimum edge distances

Bolt diameter

(in.)

1heared

edge

Rolled or

2as 0ut edge

!%& '*'%& %&

3%" '*'%" '

%& '*'% '*'%&' '*3%" '*'%"

'*'%& '*'%

'*'%" *'%" '*!%&

'*3%& *3%& '*3%"


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0O1TED CONNECTION

Example 1 Design a sli%critical slice for a tension member. @orthe Service II load combination$ the member is sub3ected to a

tension load of -- +is. @or the strength limit state$ the member is

sub3ected to a ma&imum tension load of /-- +is.

The tension member is a W8 x 28section made from *!-%Gr. "-steel. se A/" bolts to design the sli%critical slice.

Step I.Service and factored loads Service 1oad < -- +is.

@actored design load < /-- +is

Tension member is W8 x 28section made from *!- Gr."-. Thetension slice must be sli critical 8i.e.$ it must not sli9 at service loads.


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0O1TED CONNECTION

Step II.Sli%critical slice connection

Sli resistance of one full'%tensioned sli%critical bolt < 7n< =h=sNs6t < ?.- for sli%critical resistance evaluation

Assume bolt diameter < d < K in. Therefore 6t< +is from Table ?

Assume standard holes. Therefore =h< ?.-

Assume Class A surface condition. Therefore =s< -.//

Therefore$ 7n< ?.- & -.// & ? & < F. +is

Therefore$ number of K in. diameter bolts re)uired for slice to be sli%critical at service loads < -- ; F. < ?.L.

Therefore$ number of bolts re)uired M


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0O1TED CONNECTION

Step III:1a'out of flange%late slice connection

To be s'mmetric about centerline$ need the number of bolts < multile of .

Therefore$ choose full' tensioned /; in. A/" bolts (ith la'out above. Sli%critical strength of the connection < & F. +is < ?.! +is

*inimum edge distance 81e9 < ? in. from Table . Design edge distance 1e< ?." in.

*inimum sacing < s < / & bolt diameter < / & K < ." in.

Design sacing < ." in.


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0O1TED CONNECTION

Step IV:Connection strength at factored loads The connection should be designed as a normal shear;bearing

connection be'ond this oint for the factored load of /-- +is

Shear strength of high strength bolt < 7n< -.- & -./ & Ab& @ubNs

E)uation given earlier for threads included in shear lane.

Ab< /.? & -.!"; < -. in

@ub< ?- +si for A/" bolts (ith d ?%?; in.

N

s< ?

Therefore$ 7n < ?L.? +is

The shear strength of bolts < ?L.? +is;bolt & < /L.F +is


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0O1TED CONNECTION

0earing strength of /; in. bolts at edge holes 81e< ?." in.9

bb7n< -.- & ?. 1ct @u0ecause the clear edge distance < ?." 8/; J ?;?L9; < -./!" in. d

bb7n< -.- & ?. & -./!" & L" +is & t < ".L" +is ; in. thic+ness

0earing strength of of /; in. bolts at non%edge holes 8s < ."9 bb7n< -.- & . d t @u

0ecause the clear distance bet(een holes < ." 8/; J ?;?L9 < ?.L!" in. , d

bb7n< -.- & . & -.!" & L" +is & t < F/.L +is ; in. thic+ness

0earing strength of bolt holes in flanges of (ide flange section W8 x 288t < -.L" in.9

& ".L" & -.L" J?L & F/.L & -.L" < F +is


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>E1DED CONNECTIONS

Introduction The shielded metal arc (elding 8S*A>9 rocess for field (elding.

Submerged metal arc (elding 8SA>9 used for sho (elding automatic or semi%automatic rocess

Hualit' control of (elded connections is articularl' difficult because ofdefects belo( the surface$ or even minor fla(s at the surface$ (ill

escae visual detection.

>elders must be roerl' certified$ and for critical (or+$ secial

insection techni)ues such as radiograh' or ultrasonic testing must beused.


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>E1DED CONNECTIONS

T(o most common t'es of (elds are the fillet and the groove (eld. la 3oint fillet (elds laced in the corner formed b' t(o lates

Tee 3oint fillet (elds laced at the intersection of t(o lates.

Groove (elds deosited in a ga or groove bet(een t(o arts to be

connected e.g.$ butt$ tee$ and corner 3oints (ith beveled 8reared9 edges 6artial enetration groove (elds can be made from one or both sides (ith or

(ithout edge rearation.

Fillet weld

Fillet weld

Fillet weldFillet weld

Fillet weldFillet weld


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@I11ET >E1DED CONNECTIONS

The shear strength of the base metal must be considered2

7n< v& -." Ag@'

(here$ v< ?.-

@'is the 'ield strength of the base metal and Agis the gross area in shear

Strength of (eld in shear Strength of base metal

< -.- & -.L- & @e&&& -.!-! & a & 1( < ?.- & -." & @'& t & 1(

Smaller governs the strength of the (eld

T

6le+ation Plan

T

6le+ation Plan


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Lmtatons on !eld dmensons

*inimum si5e 8amin9 >eld si5e need not e&ceed the thic+ness of the thinner art 3oined.

amin deends on the thic+ness of the thic+er art 3oined

If the thic+ness of the thic+er art 3oined 8T9 is less than or e)ual to K in.amin < in.

If T is greater than K in. amin< ";?L in.

*a&imum si5e 8ama&9 *a&imum si5e of fillet (eld along edges of connected arts

for material (ith thic+ness -." in.$ ama& < thic+ness of the material for lates (ith thic+ness -." in.$ ama&< thic+ness of material % ?;?L in.

*inimum length 81(9 *inimum effective length of fillet (eld < & si5e of fillet (eld

Effective length of fillet (eld , ?." in.


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>eld terminations and end returns End returns must not be rovided around transverse stiffeners

@illet (elds that resist tensile forces not arallel to the (eld a&is orroortioned to (ithstand reeated stress shall not terminate at corners

of arts or members

>here end returns can be made in the same lane$ the' shall bereturned continuousl'$ full si5e around the corner$ for a length e)ual to

t(ice the (eld si5e 8a9


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@I11ET >E1D DESIGN

Example 1 Design the fillet (elded connection s'stem for a double

angle tension member !" & /P & ?; made from A/L steel to carr'

a factored ultimate load of "- +is.

Step I. Design the (elded connection

Considering onl' the thic+ness of the angles: amin< ?; in. Considering onl' the thic+ness of the angles: ama&< ?; % ?;?L in. < !;?L in.

"esi#n$ a < /; in. < -./!" in.

Shear strength of (eld metal < 7n < -.- & -.L- & @ENN& -.!-! & a & 1(

< .F & 1(+is

Strength of the base metal in shear < 7n< ?.- & -." & @'& t & 1(

< ?-. 1(+is

Shear strength of (eld metal governs$ 7n< .F 1(+is


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@I11ET >E1D DESIGN

Design strength 7n, "- +is Therefore$ .F 1(, "- +is

Therefore$ 1(, .? in.

Design length of /; in. E!- fillet (eld < /-.- in.

Shear stren#th o$ $illet %eld & 2'7 (ips

Connection la'out Connection must be designed to minimi5e eccentricit' of loading.

Therefore$ the center or gravit' of the (elded connection must coincide

(ith the center of gravit' of the member.

Tu

/ 5

/ 5'

5'

5

3." in.Tu

/ 5

/ 5'

5'

5

3." in.


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@I11ET >E1D DESIGN

Connection la'out

Connection must be designed to minimi5e eccentricit' of loading.

The c.g. of the (elded connection must coincide (ith c.g. of the member

Total length of (eld re)uired < /- in.

T(o angles assume each angle (ill have (eld length of ?" in.

Tu

/ 5

/ 5'

5'

5

3." in.Tu

/ 5

/ 5'

5'

5

3." in.


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@I11ET >E1D DESIGN

The tension force Tuacts along the c.g. of the member$ (hich is?.L" in. from the to and /./" in. from the bottom 8AISC manual9.

1et$ $be the strength of the fillet (eld er unit length.

Therefore$ fL1" fL2= #u

And fL2x $.$% & fL1x 1.'% = ( % ta+ing moments about the member c.g.

Therefore$ 1?< .- 10ut$ 1?J 1< ?".- in.

Therefore$ 1?< ?- in. and 1< " in.

Design2 1?< ?-.- in. and 1< ".- in.


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@I11ET >E1D DESIGN

Consider another la'out

Tu

/ 5

5'

5

/ 5'

!/ 3." iTu

/ 5

5'

5

/ 5'

!/ 3." i

f1?J f1

J "f < T

u

f1& /." J "f & -." % f1

?& ?.L" < - % *oment about member c.g.

Additionall'$ 1

?J 1

J " < ?".- in.

Therefore$ 1?< !.L in. and 1

< . in.

Design2 1?< .- in. and 1< /.- in.


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Groove >elded Connections

Connects structural members that are aligned in the same lane

0asic T'es2 Comlete 3oint enetration groove (eld2 transmits full load of the member the' 3oin

and have the same strength as the base metal.

6artial enetration groove (eld2 >elds do not e&tend comletel' through thethic+ness of the ieces being 3oined.

G


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Groove >elds

Comlete enetration groove (elded connections

Tension and comression loaded

@actored resistance < factored resistance of base metal

Shear loaded on effective area lesser of @actored resistance of (eld < -.L & e)& @e&&< -.L & -." & @e&& L-# of factored resistance of base metal in tension

6artial enetration groove%(elded connections

Tension or comression arallel to the (eld a&is and comression normalto effective area factored resistance of the base metal

Tension normal to the effective area lesser of

@actored resistance of the (eld < -.L e2@e&&< -.L- & -.- & @e&& @actored resistance of the base metal

Shear loaded lesser of @actored resistance of the (eld < -.L e2@e&&< -.L- & -.- & @e&&

@actored resistance of base metal < -." @'

Groove >elds


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Groove >elds

Documents

Pp6.Connection Design Weld