Seismic & Torsional Instability Evaluation of Multistoried Irregular RCC Building Integrated with Sp

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

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

Seismic & Torsional Instability Evaluation of Multistoried Irregular RCC Building Integrated with Special Shaped Columns

1 , Binu P2

1M.Tech student, Structural Engineering & Construction Management, SNGCE, Kadayiruppu, Kolenchery, Kerala 2Associate professor, Civil Department, SNGCE, Kadayiruppu, Kolenchery, Kerala ***

Abstract Due to visual reasons and restricted availability of land cause for irregular shaped construction and has been increased in nowadays. Irregularly structured structures will be damaged by strong earthquakes. Structural irregularities are an important factor which reduces the seismic performance of structure. There will be uneven dispersal flow and torsion in buildings with structural irregularities. In this study, normal columns of L shaped buildings werereplacedby columns of special dimensions and it would be in alternate ways, this would improve the seismic action of buildings. The best arrangement of column combinations will be identified for irregular L shaped buildings.The structural responses of building are measured in terms of story displacement, story drift, and normalized base shear force and overturning moment.

Keywords: Irregular building, strong ground motion, Structural irregularities, story drift, torsion, irregular & shaped buildings.

1. INTRODUCTION

1.1 MODELLING AND ANALYSIS OF THE BUILDING IN ETABS-2018

ThebuildingsweremodelledusingETABS.Column replacementsisconsidered:

Replacingthenormalcolumnsinthecornersbyspecial shaped columns,replacingallnormalcolumnsinbuilding byspecialshapedcolumns.

1.2 Building Geometry

Tocarryoutthestudyofseismicelasticconcertofdifferent shapedstructurethroughplanirregularitiesanLshapedplan asymmetric building has been modeled in ETABS 2018. ETABS is an engineering software product that caters towardsmultistoriederectionanalysisanddesign Planand 3DviewofthemodeledbuildingareshowninFig1.

Fig

1

:Planofthebuildingmodel

Thebuildingshaveninestorieswithatotalheightofthe28m above ground level and 1.5 m below the ground level. All storiesareof3mheightexceptgroundfloorwhichis4m. Thedimensionsoftheregularmodelfloorsare45m×45m Thedecreaseintheareaoftheirregularmodelfromaregular modelrepresentstheincreaseintheplanirregularityofthe model

Fig 2:3Dviewofthebuilding

2. MATERIAL PROPERTIES

Theconcretemixwell definedforthebeamandslabistaken as M25 and M20 respectively. Fe 500 and Fe 415 grade rebar is used as a longitudinal and confinement bar. The

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

beams are having a specific weight density about 24.9926Kn/m3andmassperunitvolumeofabout2548.538 kg/m3. The modulus of Elasticity (E) of beam is about 25000Mpa,poisonsratio(U)isabout0.2andshearmodulus (G)isabout10416.67Mpa.

Table 1: DimensionsofnewlydesignedTcolumns

Dimension (mm) Total depth (mm)

Total Width (mm)

Thickness(mm)

350*350 410 410 200 450*450 550 550 250 550*550 600 600 320

Table-2: DimensionsofnewlydesignedCrossColumns

Dimension (mm) Total Depth (mm)

Total Width(mm) Thickness(mm)

350*350 400 400 200 450*450 500 500 280 550*550 650 650 300

Table 3: Dimensions ofnewlydesignedLColumns

Dimension (mm) Total Depth(mm) Total Width (mm)

Thickness(mm)

350*350 400 400 200 450*450 480 480 320 550*550 580 580 390

3. RESULTS AND DISCUSSIONS

3.1 Seismic performance of L shaped building with T shaped columns at corners

Fig -3 : PlotofStoryOverturningMoment

Fig-4: PlotofStoryDisplacement

Fig- 5 : PlotofStoryDrift

Fig 6 : PlotofStoryShear

3.2 Seismic Performance of L shaped building with Cross shaped columns at corners

Fig 7 : PlotofStoryDisplacement

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal |

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

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

Fig -12 : PlotofStoryDrift

Fig 8 : PlotofStoryOverturningMoment

Fig -9: PlotofStoryDrift

Fig 10 : PlotofStoryShear

3.3 Seismic Performance of L shaped building with L -shaped columns at corners

Fig 13 : Plotof StoryOverturningMoment

Fig 14 : PlotofStoryShear

3.4 Seismic Performance of L shaped building whose normal columns are fully replaced with special shaped columns

Fig 15 :PlotofStoryDisplacement

Fig -11: PlotofStoryDisplacement

2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal

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

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

Table 5: ResultobtainedfromTorsionalandBuckling analysisofCrosscolumns

Location Cross shaped columns

Torsional Result (kN m)

Fig 16 :PlotofStoryOverturningMoment

Fig 17 : PlotofStoryDrift

Fig 18 : PlotofStoryShear

From figure 3 to Figure 18 shows the result of different shapeofthecolumnreplacedbycornerColumns.Fromthese analysisresultswecanseethatreplacingthefullcolumnsin buildingbydifferentshapesconsumestorydisplacement 89.733mm,storydisplacement 0.008, storyshear 8565.8 kNandoverturningmomentof55.3877kN m,hencewecan say that the building with special designed column performsbetterwhenexposedtoseismicforces.

Table 4: ResultobtainedfromTorsionalandBuckling analysisofTcolumns

Location T shaped columns

Torsional Result (kN m)

Buckling Result (kN)

A1 0.0008 0.0200

A11 0.0011 0.0191

K1 0.0026 0.0128

K5 0.3480 0.0019

E5 0.0014 0.0079

E11 0.0113 0.0925

Buckling Result (kN)

A1 0.0116 0.0447

A11 0.0083 0.1809 K1 0.0138 0.0244 K5 0.136 0.0886 E5 0.0179 0.0172 E11 0.0171 0.1111

Table 6: ResultobtainedfromTorsionalandBuckling analysisofLcolumns

Location L shaped columns

Torsional Result (kN m)

Buckling Result (kN)

A1 0.0116 0.0447

A11 0.0083 0.1809 K1 0.0138 0.0244 K5 0.0.136 0.0886 E5 0.0179 0.0172 E11 0.0171 0.1111

4. CONCLUSIONS

Thereplacementofnormalcolumnsatcornersofastructure through different shapes such as T, Cross and L shaped columns are performed with various size of 350x350, 450x450and550x550mm.Similarlyreplacementofspecial column in entire building was performed. Structural responses of changed model were measured in terms of story displacement,story drift,torsional irregularity,shear force,andoverturning moment.Followingaretheresults obtained:



From seismic analysis by replacing the corner column with special shapes, have story displacement of 89.733mm,storydisplacementof0.008705,storyshear of8565.8515kN,andoverturning momentof55.3877kN mhencewecansaythatthespecialshapedcolumnhave betterresultscomparedtoothershapes.



Bycomparingthereplacementofdifferentshapebythe corner column the special shaped column have the maximumstorydriftandstoryshearascomparedbythe other model. By comparing the torsional and buckling values of the three models, T shaped corner column showsbetterperformance.

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

Volume: 09 Issue: 07 | July 2022 www.irjet.net p ISSN: 2395 0072

ACKNOWLEDGEMENT

IwishtothanktheManagement,PrincipalandHeadofCivil EngineeringDepartmentofSNGCECollegeofEngineering, affiliated by Kerala Technological University for their support.Thispaperisbasedontheworkcarriedoutbyme (Amrutha Shaiben), as part of my PG course, under the guidanceofBinuP(Associateprofessor,CivilDepartment, SNGCE, Kadayiruppu, Kerala). I express my gratitude towardshimforvaluableguidance

REFERENCES

[1] Arvindreddy, R.J. Fernandis, “Seismic analysis of RC regularandirregularframestructures”,IRJET,Volume 02,IssueNo.05,2015.

[2] Basavaraju Y. K., Dr. B.S.Jayashankar Babu, “Seismic performanceofmultistoryRCframebuildingswithsoft storeyfrompushoveranalysis”,IJESC,Volume06,Issue No.7,2016.

[3] FederalEmergencyManagementAgency(FEMA 273), “The Guidelines for the Seismic Rehabilitation of Buildings”,Oct 1997.

[4] IS 1893 (Part 1)," Criteria for earthquake resistant designofstructures",BureauofIndianStandards,New Delhi,India,2002.

[5] Kancharla Srimukha, Ramesh Bantupalli, “Pushover Analysis of MultiStorey RCC Frame with and without Vertical Irregularities”, International Journal of Engineering and Management Research, Volume 6, Issue 4,July August2016.

[6] NareshkumarBG,TMPrakash,N.Punith,Mallamma, “Seismic analysis of multi storied building having verticalirregularitiesusingpushoveranalysis”,IRJET, Volume04,IssueNo.07,2017.

[7] Shaikh Sameer J.,S.B. Shinde “Seismic Response of Vertically Irregular RC Frame With Stiffness Irregularity at Ground Floor ”, IJARSE, Vol. 5, Issue No.09,September2016.

2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal