Comparative Study of an Educational Building by Linear Static Analysis and Response Spectrum Analysi

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

Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p ISSN: 2395 0072

Comparative Study of an Educational Building by Linear Static Analysis and Response Spectrum Analysis

1Assistant Professor, Department of Civil Engineering, Ilahia College of Engineering and Technology, Kerala 2,3,4,5 Pursuing B. Tech in Civil Engineering

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Abstract The increase in population and the scarcity of are in the expanding cities leads to the development of vertical buildings. The vertical construction helps in accommodate a huge amount of personnel in limited space. Natural hazards like earthquake, affects the stability of such structures. This requires advanced construction techniques as well as better design and analysis. Seismic analysis of such buildings should be done accurately and economically. This comparative study aims to find a median between static and dynamic analysis of a 3 storeyed building located in zone 3 in India. The main objective is to analyze and design such hazard resisting structures so, to save human life and avoid property damage and to choose an economical method of analysis.

Key Words: AUTOCAD, ETABS, Gravity Loads, Shear Force, Axial Force, Bending Moment, Displacement, Earthquake

1. INTRODUCTION

Structural analysis is basically used to determine the behaviourofastructurewhensubjectedtoloads.Theload maybedynamicorstatic.Loadduetotheweightofthings such as people, furniture, etc. are termed as static loads. Loads due to dynamic loads as wind, explosions and an earthquakeshouldalsobeconsidered.Theseismicresponse of the building depends on the type of analysis method adopted where the loads act linearly or in a non linear manner

Theanalysismethodswereconfinedtostaticapproachdue toitssimplicityandthelackinginadvancedtechnology

Staticanalysis isbasedonreplacingconceptoftheinertia forces at various considerable masses i.e. stories by equal horizontalforcesthatarecorrespondingtotheweightofthe structureanditsacceleration.Theloadsactlinearlyandthis isrepresentedintheelasticregionofastress straingraph.

Thedevelopmentoftechnologyhelpedintheadvancement ofanalysisprogramsthatenablestheresearcherstomove forwardtowardsamorerationalapproachbysimulatingthe actual effect of earthquakes on the building models. This helps to obtain the realistic seismic response and this method is categorized under dynamic analysis. Dynamic

analysis describes and expects the structural movement casesundertheinfluenceofdynamicloads

2. OBJECTIVES

TodrawtheplanofschoolbuildingusingAutoCAD2021 andthesectionsandlayoutofitsframesandslabs

To calculate and apply the gravity loads and different loadcombinationsasperIndianCodalprovisions

Toanalysethebuildingusinglinearstaticandresponse spectrumanalysisusingETABS

Todeterminethestorey displacementsfora3storeyed schoolbuilding.

Tomakecomparativestudyoftheresultsofparameters such as bending moment, shear force, axial force and displacement,obtainedfromstaticanddynamicanalysis.

3.

METHODOLOGY

PreparationofplaninAutoCAD2021

ExportingtoETABS

Assigningloadsandloadcombinations

LinearStaticAnalysishasbeenusedforstaticanalysis

Responsespectrummethodhasbeenusedfordynamic analysis

Comparisonoftheresult

3.1 Plan in AUTOCAD

AthreestoreyededucationalbuildingisdrawninAutoCAD keepinginmindtheIndianstandards.

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

Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p ISSN: 2395 0072

3.2 Design of Frames and Slabs

3.3 Exporting to ETABS

Fig. 6 Plan

Fig. 2 SlabandBeamCenterLineDrawings

Fig. 3 SectionofBeams

Fig. 7 Elevation

Fig. 8 3DView

3.4 Load Calculation for Frames

(DeadLoad=Unitweightof concrete XUnitvolumeofthe material)

Table 1 PlinthBeam

Fig. 4 FootingCenterLine

Plinth Beam

PB1

Dead Load

25×0.3×0.6=4.5kN/m

PB2 25×0.3×0.5=3.75kN/m PB3 25×0.3×0.5=3kN/m PB4 25×0.3×0.3=2.25kN/m

Table 2 Wall

Beam Dead Load

B1

25×0.25×0.6=3.75kN/m

B2 25×0.25×0.3=1.875kN/m

Fig. 5 SectionofFooting

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

Table 3 Beam Wall Dead Load

W1 25×0.3=7.5kN/m W2 25×0.3=7.5kN/m

Table 4 Slab

Floor Finish 1kN/m2

Slab Live Load (IS 875 Part 2: 2002)

Dead Load

S1 3KN/m 25×0.12×1=3kN/m2

S2 3KN/m 25×0.12×1=3kN/m2

3.8 Load Combinations

In the limit state design of reinforced and prestressed concretestructures,thefollowingloadcombinationsshallbe accountedfor: 1)DL+LL 2)1.5(DL+LL) 3)1.2(DL+LL+EQx) 4)1.2(DL+LL EQx) 5)1.2(DL+LL+EQy) 6)1.2(DL+LL EQy) 7)1.5(DL+EQx) 8)1.5(DL EQx) 9)1.5(DL+EQy) 10)1.5(DL EQy) 11)0.9DL+1.5EQx 12)0.9DL 1.5EQx 13)0.9DL+1.5EQy 14)0.9DL 1.5EQy 15)Envelope

3.9 Seismic Loading IS 1893.1.2016

1)

Directionandeccentricity

Theeccentricityofacircle=0

Theeccentricityofanellipse=between0 and1

Theeccentricityofaparabola=1

Theeccentricityofahyperbola>1

Theeccentricityofaline=infinity

XdirectionEqx

YdirectionEqy

Eccentricityratio=0.05

2) StoreyRange

Storey1 Storey4

3) Factors

Responsereductionfactoristhefactorbywhichthe actualbaseshearforceshouldbereduced,toobtain the design lateral force during design basic earthquakeshaking.Theresponsereductionfactor (R)isbasicallydependsonthestrength,Ductility, Redundancy. So, there is a need to come up with realistic R factors for different structural systems thatchangesindifferentregionsconsequently.

Responsereductionfactor=5

4) Seismic coefficients (IS 1893:2016 for Zone 4 Gujarat)

The Seismic coefficients aredimensionless coefficients which represent the maximum earthquake acceleration. It is represented as a fractionoftheaccelerationduetogravity.

Seismiczonefactor=0.24

Soilsitetype=II

Inseismicdesign,occupancyimportancefactor(IF) is a multiplier to increase or decrease the design base shear, according to different occupancy categoriesortheimportanceclassofabuilding.

Importancefactor=1.5

Timeperiod

3.10 Linear Static Analysis

Alinearstaticanalysisisananalysiswherealinearrelation holdsbetweenappliedforcesanddisplacements.Inpractice, this is applicable to structural problems where stresses remaininthelinearelasticrangeoftheusedmaterial.Ina linearstaticanalysis,themodel’sstiffnessmatrixisconstant, andthesolvingprocessisrelativelyshort.Therefore,fora firstestimate,thelinearstaticanalysisisoftenusedpriorto performingafullnonlinearanalysis.

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

Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p ISSN: 2395 0072

Fig. 9 LinearStaticAnalysis

Themaximumdisplacementobtainedis102944.203mmand theminimumdisplacementobtainedis 59002.072mm.The parametersthatweretakenintoaccountforthecomparison includes the bending moment, shear force and axial force values.

3.10.1 Bending Moment Diagram

Themaximumbendingmomentobtainedis129.6246kNm atstorey1.

Fig. 10 BendingMomentDiagram

3.10.2 Shear Force Diagram

Themaximumaxialforceobtainedis98.3727kNatstorey1.

Fig. 11 ShearForceDiagram

3.10.3 Axial Force Diagram

Themaximumaxialforceobtainedis 1461.6453kN.

Fig. 12 AxialForceDiagram

Fig. 13 DeformedShape

3.11 Response Spectrum

Theresponsespectrumanalysisoneofthemostimportant methodsofdynamicanalysis.Thisanalysisisalsoknownas modal method or the mode superposition method. It is definedasthecombinationofplotofacceleration,velocity anddisplacement.Theyareasymmetricalorhaveareasof discontinuityirregularity,intheirlinearrangeofbehavior and belong to the plastic region. From IS1893.1.2001 The designhorizontalseismiccoefficientAhforastructureshall bedeterminedbythefollowingexpression

Ah=����Sa/2����=0.0091

Fig. 14 ResponseSpectrumAnalysis

Themaximumdisplacementobtainedis3422.678mmand theminimumdisplacementobtainedis 3432.84mm.

3.11.1 Bending Moment Diagram

The bending moment force obtained is 68.7349kNm at storey4.

Fig. 15 BendingMomentDiagram

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

3.11.2 Shear Force Diagram

Thebendingmomentforceobtainedisat11.165kNatstorey 3.

4.2 Response Spectrum Analysis

Maximumdisplacementobtained=3422.5mm. 

Themaximumbendingmomentobtained=68.5kNmat storey4. 

Themaximumaxialforceobtainedis= 1451kN. 

The maximum shear force obtained is = 68.5 kN at storey3.

4.3 Comparison of Results

Fig. 16 ShearForceDiagram

3.11.3 Axial Force Diagram

Thebendingaxialforceobtainedis 1451.0105kN.

Fig. 19 DisplacementGraph

Fig. 17 AxialForceDiagram

Fig. 18 DeformedShape

4. RESULTS AND DISCUSSIONS

4.1 Linear Static Analysis

Maximumdisplacementobtained=102944mm.

Themaximumbendingmomentobtained=129.5Nmat storey1. 

Themaximumaxialforceobtained= 1461.5kN. 

Themaximumshearforceobtained=98kNatstorey1.

Fig. 20 BendingMomentGraph

Fig. 21 ShearForceGraph

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

Volume: 09 Issue: 06 | Jun 2022 www.irjet.net p ISSN: 2395 0072

Fig. 22 AxialForceGraph

5. CONCLUSIONS

ResultsfromLinearstaticanalysisandResponsespectrum analysisforaG+3storiedbuildinginseismiczone4andsoil typeII.Thebendingmomentis88.5%moreinlinearstatic analysisthanresponsespectrumanalysis.Theaxialforceis 0.73%moreinlinearstaticanalysisthanresponsespectrum analysis. The shear force is 43% more in linear static analysisthanresponsespectrumanalysis.Thedisplacement value, bending moment value, axial force value and shear forcevaluesoflinearstaticanalysisaremorethanthevalues of response spectrum analysis. So, response spectrum analysismayberecommended.

REFERENCES

1. Balaji.UandSelvarasanM.E“DesignandAnalysisofMulti Storied Building Under Static And Dynamic Loading Condition Using ETABS.” International Journal of TechnicalResearchandApplicationsVolume4,Issue4. (July Aug,2016)

2. AnirudhGottala,Dr.shaikYajdhani“ComparativeStudyof Static and Dynamic seismic Analysis of Multistoried Building.” IJSTE International Journal of Science Technology & Engineering | Volume 2 | Issue 01 | July 2015

3. MaheshN.Patil,YogeshN.Sonawane“SeismicAnalysisof Multistoried Building”, International Journal of EngineeringandInnovativeTechnology(IJEIT),Volume 4,Issue9,March2015

4. Mohammed Rizwan Sultan, D. Gouse Peera “Dynamic Analysis of Multi storey building for different shapes”, InternationalJournalofInnovativeResearchinAdvanced Engineering(IJIRAE),Issue8,Volume2(August2015).

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