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


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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


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


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


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


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


WhenWhen = 0= 0

mmLTLT = 0.6= 0.6


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EC3 LTBEC3 LTB

Same approach as for CompressionSame approach as for Compression


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

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