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8/13/2019 Eurocode 3 for Dummies
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EurocodeEurocode 3 for Dummies3 for Dummies
The Opportunities andThe Opportunities andTrapsTraps
a brief guide on element design toa brief guide on element design to
EC3EC3
Manchester Centre forCivil & Construction Engineering
Tim McCarthy
Email [email protected]
2221/03/200321/03/2003
Slides available on the webSlides available on the web
http://www2.umist.ac.uk/construction/staff/http://www2.umist.ac.uk/construction/staff/
mccarthy/index.htmmccarthy/index.htm
Follow the link from my home pageFollow the link from my home page
From 21 March 2003From 21 March 2003
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OverviewOverview
EurocodeEurocode 33
nn Current statusCurrent statusnn CoverageCoverage
PitfallsPitfalls
nn Major and minorMajor and minordifferences withdifferences withBS5950BS5950
Element DesignElement Design
nn Beams, StrutsBeams, Struts
Capacity comparisonsCapacity comparisons
Manchester Centre forCivil & Construction Engineering
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EC3 Current StatusEC3 Current Status
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EE--SCI News March 2003SCI News March 2003
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EurocodeEurocode terminilogyterminilogy
ENEN EuroNormEuroNorm
nn mandatory standardmandatory standard
ENVENV EuroNormEuroNorm VoluntaireVoluntaire
nn You can use it if you wishYou can use it if you wish
DDDD Draft for developmentDraft for development
DCDC Draft for public commentDraft for public comment
prENprEN
nn PrePre--EuroNormEuroNorm between DD and ENbetween DD and EN
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Potential pitfallsPotential pitfalls
TerminologyTerminology
nn Restricted vocabularyRestricted vocabularyChange in symbolsChange in symbols
nn More logical symbol nameMore logical symbol name
conventionsconventions
nn Lots of subscriptsLots of subscripts
Changes in valuesChanges in values
nn YoungYoungs Modulus etcs Modulus etc
Multiple documentsMultiple documents
nn Need to consult more thanNeed to consult more than
one partone part
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TerminologyTerminology
ForceForce
CapacityCapacity
nn MMcc
Design strengthDesign strengthnn ppyy
Dead loadDead load
Live loadLive load
Wind loadWind load
ActionAction
ResistanceResistance
nn MMc,Rdc,Rd
Yield strengthYield strengthnn ffyy
Permanent loadPermanent load
Variable loadVariable load
Another variable loadAnother variable load
Manchester Centre forCivil & Construction Engineering
BS5950BS5950 EC3EC3
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TerminalTerminalogyogy
Words evolved overWords evolved over
timetimeInconsistent at timesInconsistent at times
No link with concreteNo link with concrete
structural codesstructural codes
Vocabulary consistentVocabulary consistent
with meaningwith meaningConsistent across allConsistent across all
EurocodesEurocodes
Easy to translateEasy to translate
Manchester Centre forCivil & Construction Engineering
BS5950 in wonderlandBS5950 in wonderland EC3EC3
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SymbolsSymbols BBSS55995500 EEuurrooccooddee
EEllaassttiiccMMoodduulluuss ZZ WWel
PPllaassttiiccMMoodduulluuss SS WWpl
RRaaddiiuussooffGGyyrraattiioonn
rr ii
TToorrssiioonnccoonnssttaanntt JJ IItt
WWaarrppiinnggccoonnssttaanntt HH IIww
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Changes in ValuesChanges in Values
YoungYoungs Moduluss Modulus
nn BSBS -- 205000 N/mm205000 N/mmnn ECEC -- 210000 N/mm210000 N/mm
Shear modulusShear modulus
nn BSBS 79000 N/mm79000 N/mm
nn ECEC -- 81000N/mm81000N/mm
Changes in loadChanges in load
factorsfactorsnn BS 1.4Gk + 1.6BS 1.4Gk + 1.6 QkQk
nn EC 1.35Gk + 1.5EC 1.35Gk + 1.5 QkQk
Many extra loadMany extra load
combinations in ECcombinations in EC
nn Main variable actionMain variable action
nn Secondary variableSecondary variableactionaction
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Axes redefined inAxes redefined in EurocodesEurocodes
Major axis isMajor axis is yy--yy
Vertical axis isVertical axis is zz--zz
X direction is alongX direction is along
the memberthe member
This is consistent withThis is consistent with
most FE and Framemost FE and Frame
analysis softwareanalysis software
EC3 DefinitionsEC3 Definitions
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BS Section classificationBS Section classification
= (275/p= (275/pyy))0.50.5
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prEN1993 ClassificationprEN1993 Classification
DifferentDifferent
outstandoutstand
DifferentDifferent
= (235/f= (235/fyy))0.50.5
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Multiple documentsMultiple documents
The DD ENV 1993:1The DD ENV 1993:1--1 contained all the1 contained all the
information in one 300 page document.information in one 300 page document.
It also contained the National ApplicationIt also contained the National Application
DocumentDocument
prEN1993prEN1993--11--1 Contains member and1 Contains member and
frame design but omits fastenersframe design but omits fasteners
prEN1993 must be read in conjunctionprEN1993 must be read in conjunction
with the UK National Annexwith the UK National Annex
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Element DesignElement Design
BeamsBeams
nn Moment capacity/resistanceMoment capacity/resistance
nn ShearShear
nn DeflectionsDeflectionsCompression membersCompression members
LateralLateral TorsionalTorsional BucklingBuckling
Manchester Centre forCivil & Construction Engineering
y
zx
u
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Moment ResistanceMoment Resistance
Class 1 and 2
n Mc = pyS
Class 3 semi-compact
n Mc = pyZ or
Mc = pySeff
Class 4 slender
n Mc = pyZeff
Low shear
n Fv < 60 % Pv
Class 1 and 2Class 1 and 2
nn MMc,Rdc,Rd = f= fyy WWplpl //M1M1nn M1M1 == 1.05 in UK1.05 in UK
Class 3Class 3
nn MMc,Rdc,Rd = f= fyy WWel,minel,min //M1M1
Class 4Class 4
nn MMc,Rdc,Rd = f= fyy WWeff,mineff,min //M1M1Low shearLow shear
nn VVEdEd < 50% V< 50% VplRdplRd
BS5950BS5950 EC3EC3
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Shear ResistanceShear Resistance
PPvv = 0.6= 0.6 ppyyAAvv
Shear areaShear area
nn AAvv == tDtD
Shear buckling ifShear buckling if
nn d/td/t > 70> 70
VVpl,Rdpl,Rd = A= Avv ((ffyy// 3)/3)/M1M1Shear areaShear area
nn AAvv = A= A 2bt2btff +(t+(tww+2r)t+2r)tff
nn Approx = 1.04tDApprox = 1.04tD
Shear buckling ifShear buckling if
nn hhww//ttww > 72> 72
BS5950BS5950 EC3EC3
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Compression MembersCompression Members
PPcc = Ag p= Ag pcc fromfrom
Tables 23 and 24Tables 23 and 24ppcc is a function ofis a function of
BS5950 requires aBS5950 requires a
large number oflarge number of
tablestables
NNb,Rdb,Rd==A fA fyy//M1M1
is a reduction factoris a reduction factor depends ondepends onnn nonnon--dimensionaldimensional
slendernessslenderness
nn PerryPerry--RobertsonRobertson
approachapproach
?
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Compression membersCompression members
[ ]
1?but
?ff
1?
0.522
+
=
( ) 2?0,2?a10,5f ++=
1, MyaRdb fAN =
[ ] ycrya fENfA === 115.0
,
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Compression membersCompression members
Manchester Centre forCivil & Construction Engineering
1, MyaRdb fAN =
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ExampleExample
UC 203x203x60 of grade S275 is axially loaded andUC 203x203x60 of grade S275 is axially loaded andpinned at each end of its 6m length.pinned at each end of its 6m length.
A = 76.4 cmA = 76.4 cm, flange thickness,, flange thickness, tftf= 14.2mm, radius of= 14.2mm, radius ofgyration about minor axis,gyration about minor axis, iizzzz = 5.2 cm, depth, h == 5.2 cm, depth, h =209.6mm, width b = 205.8209.6mm, width b = 205.8 h/bh/b= 1.01 => H section= 1.01 => H section
Table 3.1Table 3.1:: ttff = 14.2mm < 40mm therefore= 14.2mm < 40mm therefore fyfy=275N/mm=275N/mmfor S275 gradefor S275 grade
E = 210000 N/mmE = 210000 N/mm
SlendernessSlenderness --zzzz= 600/5.2 = 115
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ButBut
EC loads are typically 5% lower than BSEC loads are typically 5% lower than BS
Scaling the capacity by this figure gives:Scaling the capacity by this figure gives:
EC3 = 760/0.95 = 800EC3 = 760/0.95 = 800 kNkN
EC3 stronger than BS at 786EC3 stronger than BS at 786 kNkN
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LTB BS5950:2000LTB BS5950:2000
MMxx MMbb//mmLTLT andand MMxxMMcxcxMMbb == ppbb modulusmodulus
ppbb fromfrom LTLTLTLT == uvuvWWClass 1 & 2:Class 1 & 2: WW = 1.0= 1.0
Class 1 & 2:Class 1 & 2: MMb =b = ppbbSSxx
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LTB BS5950:2000LTB BS5950:2000
MMxx MMbb//mmLTLT andand MMxxMMcxcxMMbb == ppbb modulusmodulus
ppbb fromfrom LTLTLTLT == uvuvWWMMb =b = ppbbSSxx
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BS 5959 Table 18BS 5959 Table 18 mmLTLT
Manchester Centre forCivil & Construction Engineering
WhenWhen = 0= 0
mmLTLT = 0.6= 0.6
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EC3 LTBEC3 LTB
Same approach as for CompressionSame approach as for Compression
Manchester Centre forCivil & Construction Engineering
1Myy.plwLTRd.b /fWM =
[ ] 5,0221
LTLTLT
LT? +
=
++= 2)2.0(15,0 LTLTLTLT
1.051.05
1.0 For UB, UC1.0 For UB, UC
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EC3 LTBEC3 LTB
LT= 0,34 for rolled UCsections
LT= 0,49 for rolled UB sections
++= 2)2.0(15,0 LTLTLTLT
The non-dimensional slenderness crRdplLT MM /.=
z
t
z
wzcr
EI
GIL
I
I
L
EICM
2
2
2
2
1
+= Where C1 results from theWhere C1 results from the
bending moment diagrambending moment diagram
WWplyply.f.fyy
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EC3 LTBEC3 LTB
Moment factor, CMoment factor, C11 loaded betweenloaded between
restraintsrestraints
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EC3 LTBEC3 LTB
Moment factor, CMoment factor, C1,1, due to end momentsdue to end moments
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Same curves as before!Same curves as before!
1Myy.plwLTRd.b /fWM =
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ExampleExample
Uniform momentUniform moment unbracedunbraced length 3mlength 3m
UB 610x229x140 S275UB 610x229x140 S275
BS MBS Mbb = 1100= 1100 kNmkNm
EC3EC3 MMbRdbRd = 960kNm= 960kNm
For comparison scale by 1/0.95For comparison scale by 1/0.95
nn MMbRdbRd scaled = 1010scaled = 1010 kNmkNm < than BS< than BS
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Summary of LTBSummary of LTB
BS5950 splits calculations betweenBS5950 splits calculations between
strength and equivalent momentstrength and equivalent momentEC3 combines equivalent moment andEC3 combines equivalent moment andsection properties to give a reductionsection properties to give a reductionfactorfactor
EC3 uses EXACT same buckling curvesEC3 uses EXACT same buckling curvesfor LTB and Strut bucklingfor LTB and Strut buckling
EC3 look awful but is easily programmedEC3 look awful but is easily programmed
in a spreadsheetin a spreadsheet
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ConclusionsConclusions
EurocodesEurocodes are not that difficultare not that difficult
They are just a little differentThey are just a little different
Rationalises terminology across materialsRationalises terminology across materials
and countriesand countries
The EFTA region is 10 times bigger thanThe EFTA region is 10 times bigger than
UKUK
EurocodesEurocodes are not going to go away thisare not going to go away this
timetime
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Questions??Questions??
1.1. How quickly will the take up be in theHow quickly will the take up be in the
UK?UK?
AnsAns: It should be quicker than the: It should be quicker than theswitch from BS449 to 5950 was sinceswitch from BS449 to 5950 was since
both EC3 and BS5950 are limit statesboth EC3 and BS5950 are limit states
codes. EC3 will become mandatory.codes. EC3 will become mandatory.
2.2. What does EC3 say about effectiveWhat does EC3 say about effective
lengths?lengths?
AnsAns: The EC3 guidance is not as: The EC3 guidance is not as
helpful as BS5950 Table 22. EC3helpful as BS5950 Table 22. EC3
gives the general approach for effectivegives the general approach for effective
lengths in frames which results in thelengths in frames which results in the
same values as Table 22same values as Table 22
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Questions??Questions??
1.1. How is Europe progressing withHow is Europe progressing with
using EC3?using EC3?
AnsAns: The German speaking countries: The German speaking countries
have already adopted the DDENV as ahave already adopted the DDENV as a
DIN. Benelux countries are wellDIN. Benelux countries are well
advanced. The rest are planning theadvanced. The rest are planning the
implementation.implementation.
2.2. WhatWhats in EC3 about sway, lambdas in EC3 about sway, lambda
critcrit etc?etc?
AnsAns: There is a lengthy section in the: There is a lengthy section in the
prENprEN on frame stability. On initialon frame stability. On initial
viewing, this looks very like theviewing, this looks very like the
BS5950:2000 approach. See Section 5BS5950:2000 approach. See Section 5
of theof the prENprEN for the full detailsfor the full details