Analysis and study of progressive collapse behaviour of reinforced concrete structure with Shear wal

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | August 2022 www.irjet.net p-ISSN: 2395-0072

Analysis and study of progressive collapse behaviour of reinforced concrete structure with Shear wall

1

2

1PG Student, Dept of civil engineering, K.L.S Gogte Institute Of Technology, Belagavi, Karnataka, India.

2Assistant Professor, Dept of civil engineering, K.L.S Gogte Institute Of Technology, Belagavi, Karnataka, India. ***

Abstract - Progressivecollapsecanbedefinedasthe failure of a structure due to the spread of a local failure of the structure. Progressive collapse is because of manmade, natural, which can be because of fires, explosions, earthquakes etc. causing failure of support elements which tendstocauseprogressivecollapsefailure.Thepurposeofthis study is to understand the nature and process of progressive collapse. This project involves the use of ETABS to perform analysis of a reinforced concrete structure. ETABS is used to observe local failure and its effect on the overall structure. Several column failure conditions are studied and as per General Service Administration (GSA) guidelines.

Key Words: Progressive Collapse, General Service Administration Guidelines, ETABS 2013

1.INTRODUCTION

Whenapartofastructurethatisassumedtohavecollapsed, orbeenseverelydamaged,byanyaccidentaleventtheterm is called localized failure. Localized failure leads to progressivecollapse. Progressivecollapseisainitiallocal failureofaverticalstructuralcomponentwhichfurtherleads to the collapse of adjoining members, which causes additionalcollapseofthestructure.Whenacolumnfails,it resultsinthefailureofadjoiningbeamandcolumns,which eventuallyleadstotheentirecollapseofthestructure.The failureofcolumnmightoccurbecauseofbombexplosion,a car colliding with column in a parking, fire explosion, earthquake. A shear wallis a vertical element that is designedtoresistlateralforces,likewindandseismicloads

2. GSA GUIDELINES

The General Services Administration (GSA) (2003) is an independentagencyoftheU.S.government.TheGSAlimits weresettodecreasethepossibilityforprogressivecollapse of a buildings and, assess the potential for progressive collapse of buildings, and develop potential upgrades to facilitiesifrequired.Theloadingcombinationaccordingto theGSAcodedependsontheanalysistype

2.1 ANALYSIS TECHNIQUE

Thefollowingstaticlinearelasticanalysisapproachmaybe used to assess the potential for progressive collapse. The

followinganalysisprocedureshallbeperformedusingwellestablished linear elastic, static analysis techniques. It is recommendedthat3-dimensionalanalyticmodelsbeusedto accountforpotential3-dimensionaleffectsandavoidoverly conservativesolutions.Nevertheless,2-dimensionalmodels may be used provided that the general response and 3dimensionaleffectscanbeadequatelyaccountedfor.

2.2 VERTICAL ELEMENT REMOVAL AS PER GSA

1) Exterior Considerations

a. Analyse for the sudden loss of a column for one floor above grade (1 story) located at or near the middleoftheshortsideofthestructure.

b. Analyse for the sudden loss of a column for one floor above grade (1 story) located at or near the middleofthelongsideofthestructure.

c. Analyse for the sudden loss of a column for one floorabovegrade(1story)locatedatthecornerof thestructure

2) Interior Considerations

a. Analyse for the sudden loss of 1 column that extendsfromtheflooroftheundergroundparking areaoruncontrolledpublicgroundfloorareatothe nextfloor(1story).Thecolumnconsideredshould beinteriortotheperimetercolumnlines.

3) SHEAR/LOAD BEARING WALLSTRUCTURE

Analyzefortheinstantaneouslossoftheentirebearingwall alongtheperimeteratthecornerstructuralbayortheloss of 30 linear feet of the wall (15ft in each major direction)(whicheverisless)foronefloorabovegrade.

3. PROBLEM DESCRIPTION

Atypicalreinforcedconcreteframedstructureof20storey height of height 3m is modeled in ETABS. This is a rectangular RC building containing :6 bays of 6m in X directionand10baysof6minYdirection.Thestoreyheight is3mandbasesupportarefixedandanalyzedusinglinear staticmethod.Theshearwallislocatedatthecornersofthe building

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | August 2022 www.irjet.net p-ISSN: 2395-0072

Theanalysisisdoneusinglinearstaticanalysismethod.The designofstructuralmembersisdoneasperIS456:2000.

Liveload:2kN/m2

Floorfinish:1.5kN/m2

Wallload:Exteriorwall=13.8kN/m Interiorwall=9kN/m

Load Combinations

Thecombinationofloadtakenintoaccountis Load=2(DL+0.25LL)

Where, DLisDeadLoadandLLisLiveLoad

2isdynamicfactor

3.2

Fig-1 planview(Shearwallsatthecorner)

3.1 DETAILS OF THE BUILDING STRUCTURE ARE

GIVEN BELOW:

Material Properties

Characteristiccompressivestrengthofconcrete(fck):30 N/mm2

YieldStrengthofreinforcingsteel(fy):500N/mm2

Section Properties

Beamsize:300x550mm

Slabthickness:150mm

Shearwallthickness:250mm Wallthickness:Exteriorwalls230mm Interiorwalls150mm

InteriorColumnssizes:

850x850mm(Baseto5th floor)

800x800mm(6th to10th floor)

650x650mm(11th to15th floor)

450x450mm(16th to20th floor)

ExteriorColumnsizes

800x800mm(Baseto5th floor)

600x650mm(6th to10th floor)

500x500mm(11th to15th floor)

450x450mm(16th to20th floor)

Loads

Deadload:Selfweightofthestructure

DEMAND CAPACITY OF RATIO (DCR)

Demand Capacity Ratio is the ratio between structural member force after removal of column to the member's ultimatestrengthorcapacityofthemember.

DCR=Qud/Que

Qud=demandingoractingforceinmemberorconnection orjoint.

Que = Un factored capacity of the member or expected ultimatestrengthofmember.

DCRacceptancecriteriaareasfollows,

DemandCapacityRatio<2.0forregularstructures.

DemandCapacityRatio<1.5forirregularstructures.

DemandCapacityRatio<3.0forsteelstructures.

Calculation of Mulimit to determine DCR for the structural members are given below.

DCR=Mu/Mulimit

Structurewithshearwall

Beam: Breadth,b=300mm Depth,D=550mm

Cover,d’=30mm

Effectivedepth,=D-d'=550-30=420mm fck=30N/mm2 fy=500N/mm2

Calculationofultimatemoment:

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Mulimit=0.133*fck*b*d*d =0.133*30*300*520*520 =323.66kN-m

Structurewithoutshearwall: Beam: Breadth,b=300mm Depth,D=500mm Cover,d’=30mm

Effectivedepth,=D-d'=500-30=470mm fck=30N/mm2 fy=500N/mm2

Calculationofultimatemoment: Mulimit=0.133*fck*b*d*d =0.133*30*300*470*470 =264.42kN-m

4 ANALYSIS AND RESULT

Reinforced concrete building is modelled in ETABS and is analyzed using linear static analysis method. Progressive collapsepotentialofabuildingisanalyzedfortwodifferent casesofcolumnremoval.

Case1:Exteriorcolumnremovalatgroundfloor

WhenColumnC66isremovedatBasefloor,mostcritically affectedcolumnsandbeamsare:

Columns:C65,67andC44andBeams:B74,B32,B75

Variations of Demand Capacity Ratios for above beams is given: BeamB74,75

Fig 4.1 PlanviewExteriorcolumnremovalatgroundfloor

Chart -1:DemandCapacityRatioV/Sstoreyofbeam BeamB32

Chart -2:DemandCapacityRatioV/Sstoreyofbeam

Case2:Interior(Central)columnremovalatgroundfloor.

Fig4.2 Planview(Interiorcolumnremovalatground floor.)

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WhenColumnC18isremovedatBasefloor,mostcritically affectedcolumnsandbeamsare:

Columns:C11,C17,C25,C19andBeams:B104,B105,B37, B36.

VariationsDCRvaluesfortheabovebeamsrespectivelyis givenasfollows

Beam36

Chart -6: DemandCapacityRatioV/Sstoreyofbeam

4.1 Comparison of DCR between structures with and without Shear wall Case 1: Exterior column removal at ground floor.

DCR value are compared for structures with and without Shearwall for

Beam74,75:

Structurewithshearwall

Chart -3: DemandCapacityRatioV/Sstoreyofbeam

Beam37

Chart -4: DemandCapacityRatioV/Sstoreyofbeam

Beam104

Chart-7:DemandCapacityRatioV/Sstoreyofbeam Structurewithoutshearwall

Chart-8:DemandCapacityRatioV/Sstoreyofbeam B74,75

Chart -5: DemandCapacityRatioV/Sstoreyofbeam

Beam105

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International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | August 2022 www.irjet.net p-ISSN: 2395-0072

Beam32: Structurewithshearwall

Chart-12:DemandCapacityRatioV/SstoreyofbeamB36

Beam37: Structurewithshearwall

Chart-9:DemandCapacityRatioV/SstoreyofbeamB32

Structurewithoutshearwall

Chart-13:DemandCapacityRatioV/SstoreyofbeamB37

Structurewithoutshearwall

Chart-10:DemandCapacityRatioV/SstoreyofbeamB32

Case 2: Interior (central) column removal at ground floor.

DCRvaluearecomparedforstructureswithandwithout Shearwall for

Beam36: Structurewithshearwall

Chart-14:DemandCapacityRatioV/SstoreyofbeamB37

Beam104: Structurewithshearwall

Chart-11:DemandCapacityRatioV/SstoreyofbeamB36

Structurewithoutshearwall

Chart-15:DemandCapacityRatioV/Sstoreyofbeam B104

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Structurewithoutshearwall

Chart-16:DemandCapacityRatioV/Sstoreyofbeam B104

Beam105:

Structurewithshearwall

Chart-17:DemandCapacityRatioV/Sstoreyofbeam B105

Structurewithoutshearwall

Chart-18:DemandCapacityRatioV/Sstoreyofbeam B105

5. CONCLUSION

Based on the analytical results, the following conclusions wereobtained:

1) Case1:Exteriorcolumnremovalatgroundfloor

i. Beams (B74,75) tends to fail from 1st to 5th storeyandbeam(B32)tendstofailfrom1stto 3rd storey, when a column is removed at 1st floor without shear wall, whereas in case of columnremovalwithshearwall(B74,75)fails at 1st storey and (B32) there was no failure observed.

ii. Axial force before and after column removal arecomparedfortheadjoiningcolumnsC65& C67,thepercentageincreaseisobservedtobe 30.9%atstorey1and18.57%atthestorey20 aftercolumnremoval.

iii. Axial force before and after column removal are compared for the columns C44 and percentageincreaseisobservedtobe19.4% at storey 1and 9.22% at the storey 20 after columnremoval

iv. ItwasobservedthattheDCRvaluesatbottom storeysexceedthelimit(2.0)comparedtotop storeys.

v. Itwasobservedthatstructurewithshearwall have higher progressive collapse resisting capacitythenstructurewithoutshearwall.

vi. Toresiststheprogressivecollapse,additional shearwallsandbracingscanbeprovided.

2) Case2:Interiorcolumnremovalatgroundfloor

i. Beam (B36) tends to fail from 1st to 19th storey,beam(B37)tendstofailfrom1st to5th storey, beam (B104) tends to fail from 1st to 19th storey,andbeam(B105)tendstofailfrom 1st to5th storey,whenacolumnisremovedat 1st floorwithoutshearwall,whereasincaseof columnremovalwithshearwallBeams(B36) tendsto failureisarrestedupto 13thstoreyfor beam(B37)failureisarrestedat1ststorey,for beam (B104)failureisupto12th storey,and beam(B105)tendstofailat1ststorey.

ii. Axialforcebeforeandaftercolumnremovalare comparedfortheadjoiningcolumnsC11&C25 andthepercentageincreaseisobservedtobe 21.93% & 21.95% at storey 1 and 12.23% & 12.25% at the 20th storey after column removal.

iii. Axialforcebeforeandaftercolumnremovalare compared for the adjoining columns C17,C19 and percentage increase is observed to be 21.96% and 21.94% at storey 1 and 12.26% &12.21% at the 20th storey after column removal

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iv. ItwasobservedthattheDCRvaluesatbottom storeysexceedthelimit(2.0)comparedtotop storeys.

v. Itwasobservedthatstructurewithshearwall have higher progressive collapse resisting capacitythenstructurewithoutshearwall.

vi. Toresiststheprogressivecollapse,additional shearwallsandbracingscanbeprovided.

ACKNOWLEDGMENT

IwouldliketothankKLSGogteInstituteofTechnology, Belagavi,Karnatakaforprovidingalltherequiredfacilities andspecialthankstofacultyforguidance.Iwouldalsoliketo thankalltherefereescitedinthispaper.

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