strut and tie deep beam solution to aci si units
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StrutandTieModelofadeepbeam
01SaturdayDec2012
PostedbyNanGaoinCaseStudies
5Comments
Tags
concretestructure,geometricmethod,SAP2000,StrutandTie,truss
AsIdiscussedinthisblogarticleStrutandtieAtoZ,STMisausefulmethodintheanalysisoftheDregionsinconcretestructures.Todayscasestudyis
usingSTMtodesignadeepbeam.ThiscaseisfromProf.JamesK.WightspaperStrutandtiemodelfordeepbeamdesign.Firstofall,IrepeatedtheSTM
modelofProf.Wight,butconvertedalltheEnglishunitsintometricunits.Itisapracticeforme.Secondly,IchooseadifferentSTMmodelandtrytofigure
aboutwhetherthissimplertriangleSTMmodelcouldwork.Thirdly,Iusedtraditionalbeamtheorytodesignthisdeepbeamandcomparedtheresultwith
theSTM
models.
The
calculation
is
based
on
Chinese
code
GB
50010
2010.
Finally,
Iused
SAP2000
to
analyze
the
same
deep
beam
and
made
acomparisonwithresultsofSTM.
1.REPEATPROF.WIGHTSSTMMODELINMETRICUNITS
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2.TRYANOTHERVERSIONOFSTMMODEL
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ComparedwithformerSTMmodel,thelongitudinalreinforcementisabitlarger,buttheverticalreinforcementinthismodelismuchsmall.However,there
aresomeissues.Theinclinedangleisverysmallandisveryneartothelowerlimit.Consideringthedecreaseintheamountofreinforcementandthe
smallerinclinedangle,maybeabettersolutionistomaketheheightofthebeamalittlehigher.Thus,theanglecouldbeabitbiggerandtheamountof
reinforcementwillnotincreasesignificantly.
3.DESIGNTHESAMEDEEPBEAMFOLLOWINGCHINESEGB500102010
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Compared
with
STM
models,
the
longitudinal
reinforcement
is
similar.
However,
the
required
amount
of
vertical
reinforcement
is
much
larger.
The
traditional
beam
theory
is
much
more
conservative
in
the
shear
design
of
STM
models.
4.ANALYZETHESAMEDEEPBEAMWITHSAP2000
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Therequiredamountoflongitudinalreinforcementintheleftpartislargerthantherightpart.OnlythefirstSTMmodelreflectsthischaracteristic.The
secondSTMmodelandthecalculationbasedonGB500102010hasthesamerequiredamountofreinforcementinthewholespan.Thus,Prof.Wights
STMmodelismorerational.
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Inthisimage,wecanseethetwozoneswhichrequiredlargeramountofverticalreinforcement.TheyarethelocationsofStrutsinSTMmodels.Also,the
Tie34inProf.Wightsmodelisreflectedinthisimage.
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Wecanseethetwobottleshapedconcretestrutsveryclearly.Thestressintheleftstrutislargerthantherightstrut.Thiscorrespondswiththeanalysisof
theSTMmodel.
References:
Wight,J.K.,andParraMontesinos,G.Strutandtiemodelfordeepbeamdesign,ACIConcreteInternational,Vol.25,No.5,2003,pp.6370
Wight,J.K.KeynoteDevelopmentoftheStrutandTieMethodforAppendixAoftheBuildingCode(ACI31808),2008