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WITHSOFTSHARMA,Dr.GARG Assocate Professor, Cv E-g-eer-g Departe-t, MANT, Bopa, Mada Prades, Asssta-t Professor, Cv E-g-eer-g Departe-t, MANT, Bopa, Mada Prades, Ma- urba- ut store bud-gs - -da toda ave ope- grou-d stor as a- u-avodabe aspect, basca to ge-erate par-g or recepto- obbes. Te upper cou- forces of te grou-d store of te gve- d‐rse ope- grou-d store bud-g. t s fou-d tat te -f pa-es tereb -creas-g te forces, dspacee-t, drft a-d ductt dea-d - te soft grou-d store. Ts coud becoe te cause of faure of ope- grou-d store bud-gs dur-g eartquae. TERMS: Ope- grou-d store, aso-r -f was, -o-‐structura eee-t, bare frae, -f stff-ess. Re-forced co-crete fraed bud-gs ave becoe coo- for of co-structo- - urba- a-d se urba- areas arou-d te word wc s aso-r -f. Nuerous suc bud-gs co-structed - rece-t tes ave a speca aspect ‐ te grou-d store s eft ope-, wc ea-s te cou-s - te grou-d store do -ot ave a- partto- was betwee- te. Tese tpes of bud-gs av-g -o -f aso-r was - grou-d store, but av-g -f was - a te upper stores, are caed as ǮOpe- rou-d Store ȋO SȌ Bud-gsǯ. Ts ope- grou-d store bud-g s aso tered as bud-g wt ǮSoft Store at Tere s sg-fca-t adva-tage of suc tpe of bud-g fu-cto-a but we- sesc perfora-ce po-t of vew suc bud-g s co-sdered t s fou-d to ave -creased vu-erabt. Te ope- grou-d store bud-gs are ge-era desg-ed as fraed structures wtout regard to structura co-trbuto- of aso-r -f was. Te prese-ce of -f was - a te upper stores ecept - te grou-d store aes te upper stores uc stffer as copared to te ope- grou-d store. Tus te upper stores ove aost togeter as a s-ge boc a-d ost of te oro-ta dspacee-t of te bud-g occurs - te soft grou-d store tsef a-d e-ce te grou-d store cou-s are eav stressed. S 1ͺͻ3 ȋ2002Ȍ recoe-ds a ag-fcato- factor of 2.5 to be apped o- be-d-g oe-ts a-d sear forces - te cou-s of grou-d store cacuated for te bare frae u-der Te sae-t obectves of te prese-t stud ave bee- to stud te effect of -f stre-gt a-d stff-ess - te sesc a-ass of ope- grou-d store ȋO SȌ bud-gs, to cec te appcabt of te utpcato- factor of 2.5 as gve- - te -da- Sta-dard S 1ͺͻ3:2002 for desg- of a d rse ope- grou-d store bud-g a-d to assess te -fue-ce of var-g te -f arra-gee-ts o- te a-ass resuts b ta-g varous cob-ato-s of -f tc-ess, stre-gt, oduus of eastct a-d ope--gs. For te stud fve dffere-t odes of a s store bud-g are co-sdered. Te bud-g as fve bas - drecto- a-d four bas - drecto- wt te pa- de-so- 22.5 × 14.4 a-d a store egt of 3.5 eac - a te foors a-d dept of fou-dato- tae- as 1.5 . Te ba wdt ao-g o-gtud-a drecto- s 4.5 a-d ao-g tra-sverse drecto- s 3.6. Te bud-g s ept setrc - bot ortogo-a drecto-s - pa- to avod torso-a respo-se u-der atera force. Te cou- s ept square a-d se of te cou- s ept sae trougout te egt of te structure to eep te dscusso- focused o- o- te soft frst store effect wtout dstracted b te ssues e ore-tato- of cou-. Te bud-g s co-sdered to be ocated - sesc o-e V a-d -te-ded for resde-ta use. M‐25 grade of co-crete a-d Fe‐415 grade of re-forc-g stee are used for a te frae odes used - ts stud. Te u-t wegts of co-crete a-d aso-r are tae- as 25.0 N/ a-d 20.0 respectve. Te oduus of eastct of te brcs fou-d - -da vares fro 350 MPa to 5000 MPa. To represe-t te etree cases of stro-g a-d wea -f was 2 cob-ato-s of -f was are co-sdered for ode-g. Te tcer wa of 230 tc-ess s cob-ed wt stro-g -f wa av-g E = 5000 MPa a-d t--er wa of 115 tc-ess s cob-ed wt wea -f wa av-g E = 350 MPa. Te poso- rato of co-crete s 0.2 a-d of aso-r s 0.15. Fgure 1: Pa- of te structure ANALYSISFoow-g fve odes are a-aed us-g respo-se spectru a-ass – Mode : Bare frae ode ȋre-forced co-crete frae ta-g -f aso-r wegt, -egect-g effect of stff-essȌ. Mode : Bud-g wt stro-g -f ȋeffect of stff-ess s aso co-sdered - addto- to ta-g wegt of -fȌ. Mode : Bud-g wt stro-g -f av-g ope--gs ȋode wt ope--gs at certa- pa-esȌ. Mode V: Bud-g wt wea -f ȋeffect of stff-ess s aso co-sdered - addto- to ta-g wegt of -fȌ. Mode V: Bud-g wt wea -f av-g ope--gs ȋode V wt ope--gs at certa- pa-esȌ. Fgure 2: Mode : Bare frae ȋaȌ Fro-t eevato- Fgure 3: Mode & V – -fed fraes ȋaȌ Fro-t eevato- ȋbȌ Sde eevato- Fgure 4: Mode & V – -fed fraes wt ope--gs FRAMEINFILLTe structura ebers are odeed wt te ad of coerca software ETABS v ͻ.7.1 - copa-ce wt te codes S 456‐2000 a-d S 1ͺͻ3‐2002. Te frae ebers are odeed wt rgd e-d co-dto-s. Te foor sabs were assued to act as daprags, wc e-sure -tegra acto- of a te atera oad‐resst-g eee-ts. Te foor f-s o- te foors s tae- to be 1.0 N/. Te ve oad o- foor s tae- as 3.0 N/ a-d tat o- te roof to be 1.5 N/. - sesc wegt cacuato-s, 25 % of te foor ve oads are co-sdered - te a-ass. For a- -f wa ocated - a atera oad‐resst-g frae, te stff-ess a-d stre-gt co-trbuto- of te -f as to be co-sdered. No-‐-tegra -f was subected to atera oad beave e dago-a struts. Tus a- -f wa ca- be odeed as a- equvae-t Ǯcopresso- o-ǯ strut - te bud-g ode. Rgd o-ts co--ect te beas a-d cou-s, but p- o-ts co--ect te equvae-t struts to te bea‐to‐cou- u-cto-s. Te e-gt of te strut s gve- b te dago-a dsta-ce ȋdȌ of te pa-e a-d ts tc-ess s equa to te tc-ess of te -f wa. Te eastc oduus of te strut s equated to te eastc oduus of aso-r ȋEȌ. St ȋ1ͻ66Ȍ proposed a forua to cacuate te wdt of strut based o- te reatve stff-ess of te frae aSHEARAs ca- be see- fro te tabes 1 & 2 ȋode to VȌ a-d fgures 5 to ͺ te be-d-g oe-ts a-d sear forces ȋstre-gtȌ dea-ds are severe ger for te grou-d store cou-s wt respect to frst store cou-s, - case of te soft grou-d store bud-gs we- te are a-aed b co-sder-g -f as structura copo-e-t ta-g -to co-sderato- ter stff-ess aso wt ter wegt. Te -troducto- of was - te frst store ȋode to VȌ reduces te force - te frst store cou-s. - ode , te be-d-g oe-t a-d sear forces are te au as copared to oter odes, as tere s -o effect of -f was co-sdered - ter a-ass wc sows te force dea-ds depe-ds upo- te stff-ess of te ebers. Aso te forces - te frst store cou-s of ode are aost equa to te forces - te grou-d store cou-s or eve- ore for sear forces wc s drastca opposte beavour as copared to te oter odes. Terefore te porta-ce of ode-g a-d co-sder-g te -f was as structura copo-e-t a-d aso te descrpto- of -f ateras, ter tpe, stre-gt a-d ter eastc oduus def-to- s reaed ere. Tabe 1: Mau be-d-g oe-t - grou-d store a-d frst store cou-s Bending(kNm) Longitudinal Transverse StoreyStoreyStoreyStorey 7ͻ7477 73 ͺ64ͺͻ0 40 ͺ251ͺ4 36 702771 2ͺ 66266ͺ 2ͺ Fgure 5: Coparso- of au be-d-g oe-ts - o-gtud-a drecto- : Coparso- of au be-d-g oe-ts - tra-sverse Mau sear force - grou-d store a-d fShearForce(kN) Longitudinal Transverse StoreyStoreyStoreyStorey 40 42 40 41 51 21 52 15 4ͻ 21 51 14 3ͻ 15 40 1ͺ 36153ͺ 1ͺ : Coparso- of au sear force - o-gtud-a drecto- : Coparso- of au sear force - tra-sverse drecto- LATERAL - o-gtud-a drecto- StoreyStoreyStoreyStoreyStorey 7.ͺ15.ͻ 23.730.435.33ͺ.0 ͺ.1ͻ.3 10.311.111.ͺ12.2 7.ͻͻ.1 10.211.011.712.2 V 6.ͺ10.7 13.ͺ16.61ͺ.71ͻ.ͻ V 6.610.4 13.616.41ͺ.51ͻ.ͺ Fgure ͻ: Dspacee-t profe ao-g o-gtud-a drecto- Tabe ‐4: Store drft ȋ- Ȍ - o-gtud-a drecto- StoreyStoreyStoreyStoreyStoreyStorey 0.6 2.0 2.32.21.ͻ1.4 0.ͺ 0.ͺ 2.0 0.360.2ͺ0.240.1ͻ 0.12 0.ͺ 1.ͻ 0.370.300.260.20 0.14 V 0.60 1.7 1.00.ͻ00.7ͺ0.60 0.35 V 0.60 1.6 1.10.ͻ20.ͺ00.62 0.36 Fgure 10: Store drfts Te dspacee-t of te ode at a te foors s te au wt respect to tat of a te oter odes. Tere s a uge dffere-ce betwee- te dspacee-t vaues of ode a-d a oter odes. Ts gap of dffere-ce s -creas-g u-for wt te -crease - te store eve. Aso te dspacee-t of ode V & V s ore ta- te dspacee-t of ode & trougout te foors. Te dspacee-t of ode s of suc aou-t because tere s -o atera stff-ess provded to te structure b te -f wa. As ca- be see- fro fgures a-d tabes for store drft, te store drft profe of ode s soot trougout wereas for ode to V te store drft ca-ges abrupt fro grou-d store to frst store. Ts sudde- ca-ge of sope of store drft profe ao-g profe of eac ode sg-fes stff-ess rreguart betwee- soft store a-d -fed store, e-cou-tered because of ode-g stff-ess of -f wa for soft grou-d store bud-gs. Suc stff-ess rreguart of soft grou-d store bud-gs s crtca fro faure po-t of vew we- subected to eartquae forces because of reseba-ce of ts beavour wt te beavour of -verted pe-duu. Te upper stores ove togeter as a s-ge boc a-d ost of te oro-ta deforato- of te bud-g occurs - te soft grou-d store tsef. Tabe 5 -dcates tat te ag-fcato- factor vaues s fou-d to var betwee- 0.ͺͺ to 1.17 for te be-d-g oe-t a-d for sear forces betwee- 0.ͻ5 to 1.33 - te grou-d store cou-s of te odes to V - coparso- to te correspo-d-g vaues of be-d-g oe-t a-d sear force - te grou-d Tabe 5: Mag-fcato- factors for be-d-g oe-t a-d sear force Mau BM - grou-d store ȋNȌ Eteror Cou- 76ͺͻ71 6ͺ Cou- 77ͻ071 6ͺ Mau sear force - grou-d store ȋNȌ Eteror Cou- 3ͻ5240 3ͺ Cou- 405240 3ͺ # Mag-fcato- factor vaues for be-d-g oe-t & sear force obta-ed b dvd-g wt te correspo-d-g vaues for te bare frae. Te foow-g are te a- f-d-gs of te prese-t stud – Te structura eber forces, deforato-s do var wt te dffere-t paraeters assocated wt te -f was. Suc varato-s are -ot co-sdered - curre-t codes a-d tus te guda-ce for te desg- of bud-gs av-g -f was s -copete a-d specfca for bud-gs wt soft grou-d store t s peratve to ave desg- gude-es - deta. -f pa-es -creases te stff-ess of te structure a-d te -crease - te ope--g perce-tage eads to a decrease o- te atera stff-ess of -fed frae. e-ce beavour of bud-g vares wt te ca-ge - -f arra-gee-ts. Ts -dcates tat ode-g of re-forced co-crete frae bud-g wtout -f wa ȋpa-eȌ or bare frae ode a -ot be approprate for te a-ass. Te a-ases resut sows tat cou- forces at te grou-d store -creases for te prese-ce of -f wa - te upper stores. But desg- force ag-fcato- factor fou-d to be uc esser ta- 2.5. Ts s partcuar true for d‐rse ope- grou-d store bud-gs. t s see- fro respo-se spectru a-ass tat te ag-fcato- factor decreases we- te stff-ess of -f pa-es are decreased eter b reduc-g -f stre-gt ȋtc-ess a-d oduus of eastctȌ or b provd-g ope--gs - te -f e- a bare frae ode s subected to atera oad, ass of eac foor acts -depe-de-t resut-g eac foor to drft wt respect to adace-t foors. Tus te bud-g frae beaves - te febe a--er caus-g dstrbuto- of oro-ta sear across foors. - prese-ce of -f wa ȋpa-eȌ, te reatve drft betwee- adace-t foors s restrcted caus-g ass of te upper foors to act togeter as a s-ge ass. - suc case, te tota -erta of te a upper foors causes a sg-fca-t -crease - oro-ta sear force at base or - te grou-d foor cou-s. Sar -creases te be-d-g oe-t Fro te prese-t resuts t s fou-d tat, atera dspacee-t s ver arge - case of bare frae as copare to tat of -fed fraes. f te effect of -f wa s co-sdered te- te defecto- as reduced drastca. Te prese-ce of was - upper stores aes te uc stffer ta- ope- grou-d store. e-ce te upper store ove aost togeter as a s-ge boc a-d ost of te oro-ta dspacee-t of te bud-g occurs - te soft grou-d store tsef. [1]. Agarwa P. a-d Sra-de M. ȋ2006Ȍ. Eartquae ressta-t desg- of structures. P ear--g Pvt. td., New [2]. Arear .N., a- S. . a-d Murt ȋ1ͻͻ7Ȍ. Sesc respo-se of RC fraes bud-gs wt soft frst stores. Proceed-gs of CBR gode- ubee co-fere-ce o- -atura aards - urba- [3]. Davs R., Me-o- D. a-d Prasad A. M. ȋ200ͺȌ. Evauato- of ag-fcato- factors for ope- grou-d store bud-gs us-g -o--ear a-ases. Te 14ord Co-fere-ce o- Eartquae E-g-eer-g, Be-g, C-a. [4]. ETABS -o--ear verso- ͻ.7.1. Ete-ded Tree De-so-a A-ass of Bud-g Sstes, Userǯs Ma-ua. Coputers a-d Structures, -c., Beree, Cafor-a, USA. [5]. S 1ͺͻ3 Part 1 ȋ2002Ȍ. Crtera for Eartquae Ressta-t Desg- of Structures. Bureau of -da- Sta-dards, [6]. S 456 ȋ2000Ȍ.Pa- a-d re-forced co-crete: Code of practce. Bureau of -da- Sta-dards, New De. [7]. Subraa-a- N. ȋ2004Ȍ. Dscusso- o- sesc perfora-ce of co-ve-to-a ut‐store bud-g wt ope- grou-d foors for vecuar par-g b a-tar a-d a-tar. Te -da- Co-crete our-a. 7ͺ, 11‐13. DharmeshVijaywargiya,Post raduate Stude-t, Cv E-g-eer-g Departe-t MANT, Bopa, Mada Prades, -da AbhaySharma,Assocate Professor, Cv E-g-eer-g Departe-t MANT, Bopa, Mada Prades, -da VivekAsssta-t Professor, Cv E-g-eer-g Departe-t MANT, Bopa, Mada Prades, -da ȏ6]Ǥ IS 456 (2000)ǤPlai- a-d rei-forced co-creteǣ Code of practiceǤ Bureau of I-dia- Sta-dardsǡ New DelhiǤ ȏ7]Ǥ Subrama-ia- NǤ (2004)Ǥ Discussio- o- seismic performa-ce of co-ve-tio-al multiǦstoreB buildi-g with ope- grou-d floors for vehicular parki-g bB Ka-itkar a-d Ka-itkarǤ The I-dia- Co-crete Jour-alǤ 78ǡ 11Ǧ13Ǥ DharmeshVijaywargiya,Post Graduate Stude-tǡ Civil E-gi-eeri-g Departme-t MANITǡ Bhopalǡ MadhBa Pradeshǡ I-dia AbhaySharma,Associate Professorǡ Civil E-gi-eeri-g Departme-t MANITǡ Bhopalǡ MadhBa Pradeshǡ I-dia VivekAssista-t Professorǡ Civil E-gi-eeri-g Departme-t MANITǡ Bhopalǡ MadhBa Pradeshǡ I-dia mag-ificatio- factor decreases whe- the stiff-ess of i-fill pa-els are decreased either bB reduci-g i-fill stre-gth (thick-ess a-d modulus of elasticitB) or bB providi-g ope-i-gs i- the i-fill Whe- a bare frame model is subjected to lateral loadǡ mass of each floor acts i-depe-de-tlB resulti-g each floor to drift with respect to adjace-t floorsǤ Thus the buildi-g frame behaves i- the fleAible ma--er causi-g distributio- of horiCo-tal shear across floorsǤ I- prese-ce of i-fill wall (pa-el)ǡ the relative drift betwee- adjace-t floors is restricted causi-g mass of the upper floors to act together as a si-gle massǤ I- such caseǡ the total i-ertia of the all upper floors causes a sig-ifica-t i-crease i- horiCo-tal shear force at base or i- the grou-d floor colum-sǤ SimilarlB i-creases the be-di-g mome-t From the prese-t results it is fou-d thatǡ lateral displaceme-t is verB large i- case of bare frame as compare to that of i-filled framesǤ If the effect of i-fill wall is co-sidered the- the deflectio- has reduced drasticallBǤ The prese-ce of walls i- upper storeBs makes them much stiffer tha- ope- grou-d storeBǤ He-ce the upper storeB move almost together as a si-gle block a-d most of the horiCo-tal displaceme-t of the buildi-g occurs i- the soft grou-d storeB itselfǤ ȏ1]Ǥ Agarwal PǤ a-d Shrikha-de MǤ (2006)Ǥ Earthquake resista-t desig- of structuresǤ PHI Lear-i-g PvtǤ LtdǤǡ New ȏ2]Ǥ Arlekar JǤNǤǡ Jai- SǤ KǤ a-d MurtB (1997)Ǥ Seismic respo-se of RC frames buildi-gs with soft first storeBsǤ Proceedi-gs of CBRI golde- jubilee co-fere-ce o- -atural haCards i- urba- ȏ3]Ǥ Davis RǤǡ Me-o- DǤ a-d Prasad AǤ MǤ (2008)Ǥ Evaluatio- of mag-ificatio- factors for ope- grou-d storeB buildi-gs usi-g -o-li-ear a-alBsesǤ The 14World Co-fere-ce o- Earthquake E-gi-eeri-gǡ Beiji-gǡ Chi-aǤ ȏ4]Ǥ ETABS -o-li-ear versio- 9Ǥ7Ǥ1Ǥ EAte-ded Three Dime-sio-al A-alBsis of Buildi-g SBstemsǡ User’s Ma-ualǤ Computers a-d Structuresǡ I-cǤǡ BerkeleBǡ Califor-iaǡ USAǤ ȏ5]Ǥ IS 1893 Part 1 (2002)Ǥ Criteria for Earthquake Resista-t Desig- of StructuresǤ Bureau of I-dia- Sta-dardsǡ Table 5ǣ Mag-ificatio- factors for be-di-g mome-t a-d shear force IIIIIIV MaAimum BM i- grou-d storeB (kNm) EAterior Colum- 768971 68 Colum- 779071 68 MaAimum shear force i- grou-d storeB (kN) EAterior Colum- 395240 38 Colum- 405240 38 # Mag-ificatio- factor values for be-di-g mome-t Ƭ shear force obtai-ed bB dividi-g with the correspo-di-g values for the bare frameǤ The followi-g are the mai- fi-di-gs of the prese-t studB – The structural member forcesǡ deformatio-s do varB with the differe-t parameters associated with the i-fill wallsǤ Such variatio-s are -ot co-sidered i- curre-t codes a-d thus the guida-ce for the desig- of buildi-gs havi-g i-fill walls is i-complete a-d specificallB for buildi-gs with soft grou-d storeB it is imperative to have desig- guideli-es i- detailǤ I-fill pa-els i-creases the stiff-ess of the structure a-d the i-crease i- the ope-i-g perce-tage leads to a decrease o- the lateral stiff-ess of i-filled frameǤ He-ce behaviour of buildi-g varies with the cha-ge i- i-fill arra-geme-tsǤ This i-dicates that modelli-g of rei-forced co-crete frame buildi-g without i-fill wall (pa-el) or bare frame model maB -ot be appropriate for the a-alBsisǤ The a-alBses result shows that colum- forces at the grou-d storeB i-creases for the prese-ce of i-fill wall i- the upper storeBsǤ But desig- force mag-ificatio- factor fou-d to be much lesser tha- 2Ǥ5Ǥ This is particularlB true for midǦrise ope- grou-d storeB buildi-gsǤ It is see- from respo-se spectrum a-alBsis that the Figure 10ǣ StoreB drifts The displaceme-t of the model I at all the floors is the maAimum with respect to that of all the other modelsǤ There is a huge differe-ce betwee- the displaceme-t values of model I a-d all other modelsǤ This gap of differe-ce is i-creasi-g u-iformlB with the i-crease i- the storeB levelǤ Also the displaceme-t of model IV Ƭ V is more tha- the displaceme-t of model II Ƭ III throughout the floorsǤ The displaceme-t of model I is of such amou-t because there is -o lateral stiff-ess provided to the structure bB the i-fill wallǤ As ca- be see- from figures a-d tables for storeB driftǡ the storeB drift profile of model I is smooth throughout whereas for model II to V the storeB drift cha-ges abruptlB from grou-d storeB to first storeBǤ This sudde- cha-ge of slope of storeB drift profile alo-g profile of each model sig-ifies stiff-ess irregularitB betwee- soft storeB a-d i-filled storeBǡ e-cou-tered because of modelli-g stiff-ess of i-fill wall for soft grou-d storeB buildi-gsǤ Such stiff-ess irregularitB of soft grou-d storeB buildi-gs is critical from failure poi-t of view whe- subjected to earthquake forces because of resembla-ce of its behaviour with the behaviour of i-verted pe-dulumǤ The upper storeBs move together as a si-gle block a-d most of the horiCo-tal deformatio- of the buildi-g occurs i- the soft grou-d storeB itselfǤ Table 5 i-dicates that the mag-ificatio- factor values is fou-d to varB betwee- 0Ǥ88 to 1Ǥ17 for the be-di-g mome-t a-d for shear forces betwee- 0Ǥ95 to 1Ǥ33 i- the grou-d storeB colum-s of the models II to V i- compariso- to the correspo-di-g values of be-di-g mome-t a-d shear force i- the grou-d I 7Ǥ815Ǥ9 23Ǥ730Ǥ435Ǥ338Ǥ0 II 8Ǥ19Ǥ3 10Ǥ311Ǥ111Ǥ812Ǥ2 III 7Ǥ99Ǥ1 10Ǥ211Ǥ011Ǥ712Ǥ2 IV 6Ǥ810Ǥ7 13Ǥ816Ǥ618Ǥ719Ǥ9 V 6Ǥ610Ǥ4 13Ǥ616Ǥ418Ǥ519Ǥ8 Figure 9ǣ Displaceme-t profile alo-g lo-gitudi-al directio- Table Ǧ4ǣ StoreB drift (i- mm) i- lo-gitudi-al directio- StoreyStoreyStoreyStoreyStoreyStorey 0Ǥ6 2Ǥ0 2Ǥ32Ǥ21Ǥ91Ǥ4 0Ǥ8 II 0Ǥ8 2Ǥ0 0Ǥ360Ǥ280Ǥ240Ǥ19 0Ǥ12 III 0Ǥ8 1Ǥ9 0Ǥ370Ǥ300Ǥ260Ǥ20 0Ǥ14 IV 0Ǥ60 1Ǥ7 1Ǥ00Ǥ900Ǥ780Ǥ60 0Ǥ35 V 0Ǥ60 1Ǥ6 1Ǥ10Ǥ920Ǥ800Ǥ62 0Ǥ36 ǣ Compariso- of maAimum be-di-g mome-ts i- tra-sverse MaAimum shear force i- grou-d storeB a-d fiShearForce(kN) Longitudinal Transverse StoreyStoreyStoreyStorey 40 42 40 41 51 21 52 15 49 21 51 14 39 15 40 18 361538 18 ǣ Compariso- of maAimum shear force i- lo-gitudi-al directio- ǣ Compariso- of maAimum shear force i- tra-sverse directio- LATERAL i- lo-gitudi-al directio- StoreyStoreyStoreyStoreyStorey of the soft grou-d storeB buildi-gs whe- theB are a-alBCed bB co-sideri-g i-fill as structural compo-e-t taki-g i-to co-sideratio- their stiff-ess also with their weightǤ The i-troductio- of walls i- the first storeB (model II to V) reduces the force i- the first storeB colum-sǤ I- model Iǡ the be-di-g mome-t a-d shear forces are the maAimum as compared to other modelsǡ as there is -o effect of i-fill walls co-sidered i- their a-alBsis which shows the force dema-ds depe-ds upo- the stiff-ess of the membersǤ Also the forces i- the first storeB colum-s of model I are almost equal to the forces i- the grou-d storeB colum-s or eve- more for shear forces which is drasticallB opposite behaviour as compared to the other modelsǤ Therefore the importa-ce of modelli-g a-d co-sideri-g the i-fill walls as structural compo-e-t a-d also the descriptio- of i-fill materialsǡ their tBpeǡ stre-gth a-d their elastic modulus defi-itio- is realiCed hereǤ Table 1ǣ MaAimum be-di-g mome-t i- grou-d storeB a-d first storeB colum-s Bending(kNm) Longitudinal Transverse StoreyStoreyStoreyStorey 797477 73 864890 40 825184 36 702771 28 662668 28 Figure 5ǣ Compariso- of maAimum be-di-g mome-ts i- lo-gitudi-al directio- (b) Side elevatio- Figure 4ǣ Model III Ƭ V – I-filled frames with ope-i-gs FRAMEINFILLThe structural members are modelled with the aid of commercial software ETABS v 9Ǥ7Ǥ1 i- complia-ce with the codes IS 456Ǧ2000 a-d IS 1893Ǧ2002Ǥ The frame members are modelled with rigid e-d co-ditio-sǤ The floor slabs were assumed to act as diaphragmsǡ which e-sure i-tegral actio- of all the lateral loadǦresisti-g eleme-tsǤ The floor fi-ish o- the floors is take- to be 1Ǥ0 kN/mǤ The live load o- floor is take- as 3Ǥ0 kN/m a-d that o- the roof to be 1Ǥ5 kN/mǤ I- seismic weight calculatio-sǡ 25 Ψ of the floor live loads are co-sidered i- the a-alBsisǤ For a- i-fill wall located i- a lateral loadǦresisti-g frameǡ the stiff-ess a-d stre-gth co-tributio- of the i-fill has to be co-sideredǤ No-Ǧi-tegral i-fill walls subjected to lateral load behave like diago-al strutsǤ Thus a- i-fill wall ca- be modelled as a- equivale-t ‘compressio- o-lB’ strut i- the buildi-g modelǤ Rigid joi-ts co--ect the beams a-d colum-sǡ but pi- joi-ts co--ect the equivale-t struts to the beamǦtoǦcolum- ju-ctio-sǤ The le-gth of the strut is give- bB the diago-al dista-ce (d) of the pa-el a-d its thick-ess is equal to the thick-ess of the i-fill wallǤ The elastic modulus of the strut is equated to the elastic modulus of maso-rB (E)Ǥ Smith (1966) proposed a formula to calculate the width of strut based o- the relative stiff-ess of the frame aSHEARAs ca- be see- from the tables 1 Ƭ 2 (model II to V) a-d figures 5 to 8 the be-di-g mome-ts a-d shear forces (stre-gth) dema-ds are severelB higher for the grou-d storeB colum-s with respect to first storeB colum-sǡ i- case ANALYSISFollowi-g five models are a-alBCed usi-g respo-se spectrum a-alBsis – Model Iǣ Bare frame model (rei-forced co-crete frame taki-g i-fill maso-rB weightǡ -eglecti-g effect of stiff-ess)Ǥ Model IIǣ Buildi-g with stro-g i-fill (effect of stiff-ess is also co-sidered i- additio- to taki-g weight of i-fill)Ǥ Model IIIǣ Buildi-g with stro-g i-fill havi-g ope-i-gs (model II with ope-i-gs at certai- pa-els)Ǥ Model IVǣ Buildi-g with weak i-fill (effect of stiff-ess is also co-sidered i- additio- to taki-g weight of i-fill)Ǥ Model Vǣ Buildi-g with weak i-fill havi-g ope-i-gs (model IV with ope-i-gs at certai- pa-els)Ǥ Figure 2ǣ Model Iǣ Bare frame (a) Fro-t elevatio- Figure 3ǣ Model II Ƭ IV – I-filled frames (a) Fro-t elevatio- of 2Ǥ5 as give- i- the I-dia- Sta-dard IS 1893ǣ2002 for desig- of a mid rise ope- grou-d storeB buildi-g a-d to assess the i-flue-ce of varBi-g the i-fill arra-geme-ts o- the a-alBsis results bB taki-g various combi-atio-s of i-fill thick-essǡ stre-gthǡ modulus of elasticitB a-d ope-i-gsǤ For the studB five differe-t models of a siA storeB buildi-g are co-sideredǤ The buildi-g has five baBs i- X directio- a-d four baBs i- Y directio- with the pla- dime-sio- 22Ǥ5 m έ 14Ǥ4 m a-d a storeB height of 3Ǥ5 m each i- all the floors a-d depth of fou-datio- take- as 1Ǥ5 mǤ The baB width alo-g lo-gitudi-al directio- is 4Ǥ5m a-d alo-g tra-sverse directio- is 3Ǥ6mǤ The buildi-g is kept sBmmetric i- both orthogo-al directio-s i- pla- to avoid torsio-al respo-se u-der lateral forceǤ The colum- is kept square a-d siCe of the colum- is kept same throughout the height of the structure to keep the discussio- focused o-lB o- the soft first storeB effect without distracted bB the issues like orie-tatio- of colum-Ǥ The buildi-g is co-sidered to be located i- seismic Co-e IV a-d i-te-ded for reside-tial useǤ MǦ25 grade of co-crete a-d FeǦ415 grade of rei-forci-g steel are used for all the frame models used i- this studBǤ The u-it weights of co-crete a-d maso-rB are take- as 25Ǥ0 kN/m a-d 20Ǥ0 respectivelBǤ The modulus of elasticitB of the bricks fou-d i- I-dia varies from 350 MPa to 5000 MPaǤ To represe-t the eAtreme cases of stro-g a-d weak i-fill walls 2 combi-atio-s of i-fill walls are co-sidered for modelli-gǤ The thicker wall of 230mm thick-ess is combi-ed with stro-g i-fill wall havi-g E α 5000 MPa a-d thi--er wall of 115mm thick-ess is combi-ed with weak i-fill wall havi-g E α 350 MPaǤ The poiso- ratio of co-crete is 0Ǥ2 a-d of maso-rB is 0Ǥ15Ǥ Figure 1ǣ Pla- of the structure colum- forces of the grou-d storeB of the give- midǦrise ope- grou-d storeB buildi-gǤ It is fou-d that the i-fill pa-els itherebB i-creasi-g the forcesǡ displaceme-tǡ drift a-d ductilitB dema-d i- the soft grou-d storeBǤ This could become the cause of failure of ope- grou-d storeB buildi-gs duri-g earthquakeǤ TERMS: Ope- grou-d storeBǡ maso-rB i-fill wallsǡ -o-Ǧstructural eleme-tǡ bare frameǡ i-fill stiff-essǤ Rei-forced co-crete framed buildi-gs have become commo- form of co-structio- i- urba- a-d semi urba- areas arou-d the world which is maso-rB i-fillǤ Numerous such buildi-gs co-structed i- rece-t times have a special aspect Ǧ the grou-d storeB is left ope-ǡ which mea-s the colum-s i- the grou-d storeB do -ot have a-B partitio- walls betwee- themǤ These tBpes of buildi-gs havi-g -o i-fill maso-rB walls i- grou-d storeBǡ but havi-g i-fill walls i- all the upper storeBsǡ are called as ‘Ope- Grou-d StoreB (OGS) Buildi-gs’Ǥ This ope- grou-d storeB buildi-g is also termed as buildi-g with ‘Soft StoreB at There is sig-ifica-t adva-tage of such tBpe of buildi-g fu-ctio-allB but whe- seismic performa-ce poi-t of view such buildi-g is co-sidered it is fou-d to have i-creased vul-erabilitBǤ The ope- grou-d storeB buildi-gs are ge-erallB desig-ed as framed structures without regard to structural co-tributio- of maso-rB i-fill wallsǤ The prese-ce of i-fill walls i- all the upper stories eAcept i- the grou-d storeB makes the upper stories much stiffer as compared to the ope- grou-d storeBǤ Thus the upper stories move almost together as a si-gle block a-d most of the horiCo-tal displaceme-t of the buildi-g occurs i- the soft grou-d storeB itself a-d he-ce the grou-d storeB colum-s are heavilB stressedǤ IS 1893 (2002) recomme-ds a mag-ificatio- factor of 2Ǥ5 to be applied o- be-di-g mome-ts a-d shear forces i- the colum-s of grou-d storeB calculated for the bare frame u-der The salie-t objectives of the prese-t studB have bee- to studB the effect of i-fill stre-gth a-d stiff-ess i- the seismic a-alBsis of ope- grou-d storeB (OGS) buildi-gsǡ to check the applicabilitB of the multiplicatio- factor WITHSOFTSHARMA,Dr.GARGPost Graduate Stude-tǡ Civil E-gi-eeri-g Departme-tǡ MANITǡ Bhodharmesh2405@gmailǤcom Associate Professorǡ Civil E-gi-eeri-g Departme-tǡ MANITǡ Bhopalǡ MadhBa Pradeshǡ Assista-t Professorǡ Civil E-gi-eeri-g Departme-tǡ MANITǡ Bhopalǡ MadhBa Pradeshǡ vivek_garg5@BahooǤcoǤi- Ma-B urba- multi storeB buildi-gs i- I-dia todaB have ope- grou-d storB as a- u-avoidable aspectǡ basicallB to ge-erate parki-g or receptio- lobbiesǤ The upper storeBs have brick i-filled wall pa-els with various ope-i-g perce-tage i- themǤ These tBpes of buildi-gs are -ot desirable i- seismicallB active areas because various vertical irregularities are i-duced i- such buildi-gs which have performed co-siste-tlB poor duri-g past earthquakesǤ It has bee- k-ow- si-ce lo-g time that maso-rB i-fill walls affect the stre-gth a-d stiff-ess of i-filled framed structuresǤ I-fill walls are ge-erallB see- as a -o-Ǧstructural eleme-t a-d their effect is -eglected bB ig-ori-g the stiff-ess of the i-fill wall duri-g the modelli-g phase of the structure (a-alBsed as a ‘li-ear bare frame’) leadi-g to substa-tial i-accuracB i- obtai-i-g the actual seismic respo-se of framed structuresǤ The objective of the paper is to check the applicabilitB of the multiplicatio- factor of 2Ǥ5 for the give- buildi-g of mid height a-d to studB the i-flue-ce of i-fill stre-gth a-d stiff-ess i- the seismic a-alBsis of a mid rise ope- grou-d storeB buildi-gǤ A rei-forced co-crete framed buildi-g (GΪ5) with ope- grou-d storeB located i- Seismic Zo-eǦIV is co-sidered for this studBǤ This buildi-g is a-alBCed for two differe-t casesǣ (a) co-sideri-g both i-fill mass a-d i-fill stiff-ess a-d (b) co-sideri-g i-fill mass but without co-sideri-g i-fill stiff-ess bB respo-se spectrum a-alBsis methodǤ The result shows that the effect of i-fill’s stiff-ess o- structural respo-se is sig-ifica-t u-der lateral loadsǤ The mag-ificatio- factor of 2Ǥ5 is high to be multiplied to ȏ6]Ǥ IS 456 (2000)ǤPlai- a-d rei-forced co-creteǣ Code of practiceǤ Bureau of I-dia- Sta-dardsǡ New DelhiǤ ȏ7]Ǥ Subrama-ia- NǤ (2004)Ǥ Discussio- o- seismic performa-ce of co-ve-tio-al multiǦstoreB buildi-g with ope- grou-d floors for vehicular parki-g bB Ka-itkar a-d Ka-itkarǤ The I-dia- Co-crete Jour-alǤ 78ǡ 11Ǧ13Ǥ DharmeshVijaywargiya,Post Graduate Stude-tǡ Civil E-gi-eeri-g Departme-t MANITǡ Bhopalǡ MadhBa Pradeshǡ I-dia AbhaySharma,Associate Professorǡ Civil E-gi-eeri-g Departme-t MANITǡ Bhopalǡ MadhBa Pradeshǡ I-dia VivekAssista-t Professorǡ Civil E-gi-eeri-g Departme-t MANITǡ Bhopalǡ MadhBa Pradeshǡ I-dia mag-ificatio- factor decreases whe- the stiff-ess of i-fill pa-els are decreased either bB reduci-g i-fill stre-gth (thick-ess a-d modulus of elasticitB) or bB providi-g ope-i-gs i- the i-fill Whe- a bare frame model is subjected to lateral loadǡ mass of each floor acts i-depe-de-tlB resulti-g each floor to drift with respect to adjace-t floorsǤ Thus the buildi-g frame behaves i- the fleAible ma--er causi-g distributio- of horiCo-tal shear across floorsǤ I- prese-ce of i-fill wall (pa-el)ǡ the relative drift betwee- adjace-t floors is restricted causi-g mass of the upper floors to act together as a si-gle massǤ I- such caseǡ the total i-ertia of the all upper floors causes a sig-ifica-t i-crease i- horiCo-tal shear force at base or i- the grou-d floor colum-sǤ SimilarlB i-creases the be-di-g mome-t From the prese-t results it is fou-d thatǡ lateral displaceme-t is verB large i- case of bare frame as compare to that of i-filled framesǤ If the effect of i-fill wall is co-sidered the- the deflectio- has reduced drasticallBǤ The prese-ce of walls i- upper storeBs makes them much stiffer tha- ope- grou-d storeBǤ He-ce the upper storeB move almost together as a si-gle block a-d most of the horiCo-tal displaceme-t of the buildi-g occurs i- the soft grou-d storeB itselfǤ ȏ1]Ǥ Agarwal PǤ a-d Shrikha-de MǤ (2006)Ǥ Earthquake resista-t desig- of structuresǤ PHI Lear-i-g PvtǤ LtdǤǡ New ȏ2]Ǥ Arlekar JǤNǤǡ Jai- SǤ KǤ a-d MurtB (1997)Ǥ Seismic respo-se of RC frames buildi-gs with soft first storeBsǤ Proceedi-gs of CBRI golde- jubilee co-fere-ce o- -atural haCards i- urba- ȏ3]Ǥ Davis RǤǡ Me-o- DǤ a-d Prasad AǤ MǤ (2008)Ǥ Evaluatio- of mag-ificatio- factors for ope- grou-d storeB buildi-gs usi-g -o-li-ear a-alBsesǤ The 14World Co-fere-ce o- Earthquake E-gi-eeri-gǡ Beiji-gǡ Chi-aǤ ȏ4]Ǥ ETABS -o-li-ear versio- 9Ǥ7Ǥ1Ǥ EAte-ded Three Dime-sio-al A-alBsis of Buildi-g SBstemsǡ User’s Ma-ualǤ Computers a-d Structuresǡ I-cǤǡ BerkeleBǡ Califor-iaǡ USAǤ ȏ5]Ǥ IS 1893 Part 1 (2002)Ǥ Criteria for Earthquake Resista-t Desig- of StructuresǤ Bureau of I-dia- Sta-dardsǡ Table 5ǣ Mag-ificatio- factors for be-di-g mome-t a-d shear force IIIIIIV MaAimum BM i- grou-d storeB (kNm) EAterior Colum- 768971 68 Colum- 779071 68 MaAimum shear force i- grou-d storeB (kN) EAterior Colum- 395240 38 Colum- 405240 38 # Mag-ificatio- factor values for be-di-g mome-t Ƭ shear force obtai-ed bB dividi-g with the correspo-di-g values for the bare frameǤ The followi-g are the mai- fi-di-gs of the prese-t studB – The structural member forcesǡ deformatio-s do varB with the differe-t parameters associated with the i-fill wallsǤ Such variatio-s are -ot co-sidered i- curre-t codes a-d thus the guida-ce for the desig- of buildi-gs havi-g i-fill walls is i-complete a-d specificallB for buildi-gs with soft grou-d storeB it is imperative to have desig- guideli-es i- detailǤ I-fill pa-els i-creases the stiff-ess of the structure a-d the i-crease i- the ope-i-g perce-tage leads to a decrease o- the lateral stiff-ess of i-filled frameǤ He-ce behaviour of buildi-g varies with the cha-ge i- i-fill arra-geme-tsǤ This i-dicates that modelli-g of rei-forced co-crete frame buildi-g without i-fill wall (pa-el) or bare frame model maB -ot be appropriate for the a-alBsisǤ The a-alBses result shows that colum- forces at the grou-d storeB i-creases for the prese-ce of i-fill wall i- the upper storeBsǤ But desig- force mag-ificatio- factor fou-d to be much lesser tha- 2Ǥ5Ǥ This is particularlB true for midǦrise ope- grou-d storeB buildi-gsǤ It is see- from respo-se spectrum a-alBsis that the Figure 10ǣ StoreB drifts The displaceme-t of the model I at all the floors is the maAimum with respect to that of all the other modelsǤ There is a huge differe-ce betwee- the displaceme-t values of model I a-d all other modelsǤ This gap of differe-ce is i-creasi-g u-iformlB with the i-crease i- the storeB levelǤ Also the displaceme-t of model IV Ƭ V is more tha- the displaceme-t of model II Ƭ III throughout the floorsǤ The displaceme-t of model I is of such amou-t because there is -o lateral stiff-ess provided to the structure bB the i-fill wallǤ As ca- be see- from figures a-d tables for storeB driftǡ the storeB drift profile of model I is smooth throughout whereas for model II to V the storeB drift cha-ges abruptlB from grou-d storeB to first storeBǤ This sudde- cha-ge of slope of storeB drift profile alo-g profile of each model sig-ifies stiff-ess irregularitB betwee- soft storeB a-d i-filled storeBǡ e-cou-tered because of modelli-g stiff-ess of i-fill wall for soft grou-d storeB buildi-gsǤ Such stiff-ess irregularitB of soft grou-d storeB buildi-gs is critical from failure poi-t of view whe- subjected to earthquake forces because of resembla-ce of its behaviour with the behaviour of i-verted pe-dulumǤ The upper storeBs move together as a si-gle block a-d most of the horiCo-tal deformatio- of the buildi-g occurs i- the soft grou-d storeB itselfǤ Table 5 i-dicates that the mag-ificatio- factor values is fou-d to varB betwee- 0Ǥ88 to 1Ǥ17 for the be-di-g mome-t a-d for shear forces betwee- 0Ǥ95 to 1Ǥ33 i- the grou-d storeB colum-s of the models II to V i- compariso- to the correspo-di-g values of be-di-g mome-t a-d shear force i- the grou-d I 7Ǥ815Ǥ9 23Ǥ730Ǥ435Ǥ338Ǥ0 II 8Ǥ19Ǥ3 10Ǥ311Ǥ111Ǥ812Ǥ2 III 7Ǥ99Ǥ1 10Ǥ211Ǥ011Ǥ712Ǥ2 IV 6Ǥ810Ǥ7 13Ǥ816Ǥ618Ǥ719Ǥ9 V 6Ǥ610Ǥ4 13Ǥ616Ǥ418Ǥ519Ǥ8 Figure 9ǣ Displaceme-t profile alo-g lo-gitudi-al directio- Table Ǧ4ǣ StoreB drift (i- mm) i- lo-gitudi-al directio- StoreyStoreyStoreyStoreyStoreyStorey 0Ǥ6 2Ǥ0 2Ǥ32Ǥ21Ǥ91Ǥ4 0Ǥ8 II 0Ǥ8 2Ǥ0 0Ǥ360Ǥ280Ǥ240Ǥ19 0Ǥ12 III 0Ǥ8 1Ǥ9 0Ǥ370Ǥ300Ǥ260Ǥ20 0Ǥ14 IV 0Ǥ60 1Ǥ7 1Ǥ00Ǥ900Ǥ780Ǥ60 0Ǥ35 V 0Ǥ60 1Ǥ6 1Ǥ10Ǥ920Ǥ800Ǥ62 0Ǥ36 ǣ Compariso- of maAimum be-di-g mome-ts i- tra-sverse MaAimum shear force i- grou-d storeB a-d fiShearForce(kN) Longitudinal Transverse StoreyStoreyStoreyStorey 40 42 40 41 51 21 52 15 49 21 51 14 39 15 40 18 361538 18 ǣ Compariso- of maAimum shear force i- lo-gitudi-al directio- ǣ Compariso- of maAimum shear force i- tra-sverse directio- LATERAL i- lo-gitudi-al directio- StoreyStoreyStoreyStoreyStorey of the soft grou-d storeB buildi-gs whe- theB are a-alBCed bB co-sideri-g i-fill as structural compo-e-t taki-g i-to co-sideratio- their stiff-ess also with their weightǤ The i-troductio- of walls i- the first storeB (model II to V) reduces the force i- the first storeB colum-sǤ I- model Iǡ the be-di-g mome-t a-d shear forces are the maAimum as compared to other modelsǡ as there is -o effect of i-fill walls co-sidered i- their a-alBsis which shows the force dema-ds depe-ds upo- the stiff-ess of the membersǤ Also the forces i- the first storeB colum-s of model I are almost equal to the forces i- the grou-d storeB colum-s or eve- more for shear forces which is drasticallB opposite behaviour as compared to the other modelsǤ Therefore the importa-ce of modelli-g a-d co-sideri-g the i-fill walls as structural compo-e-t a-d also the descriptio- of i-fill materialsǡ their tBpeǡ stre-gth a-d their elastic modulus defi-itio- is realiCed hereǤ Table 1ǣ MaAimum be-di-g mome-t i- grou-d storeB a-d first storeB colum-s Bending(kNm) Longitudinal Transverse StoreyStoreyStoreyStorey 797477 73 864890 40 825184 36 702771 28 662668 28 Figure 5ǣ Compariso- of maAimum be-di-g mome-ts i- lo-gitudi-al directio- (b) Side elevatio- Figure 4ǣ Model III Ƭ V – I-filled frames with ope-i-gs FRAMEINFILLThe structural members are modelled with the aid of commercial software ETABS v 9Ǥ7Ǥ1 i- complia-ce with the codes IS 456Ǧ2000 a-d IS 1893Ǧ2002Ǥ The frame members are modelled with rigid e-d co-ditio-sǤ The floor slabs were assumed to act as diaphragmsǡ which e-sure i-tegral actio- of all the lateral loadǦresisti-g eleme-tsǤ The floor fi-ish o- the floors is take- to be 1Ǥ0 kN/mǤ The live load o- floor is take- as 3Ǥ0 kN/m a-d that o- the roof to be 1Ǥ5 kN/mǤ I- seismic weight calculatio-sǡ 25 Ψ of the floor live loads are co-sidered i- the a-alBsisǤ For a- i-fill wall located i- a lateral loadǦresisti-g frameǡ the stiff-ess a-d stre-gth co-tributio- of the i-fill has to be co-sideredǤ No-Ǧi-tegral i-fill walls subjected to lateral load behave like diago-al strutsǤ Thus a- i-fill wall ca- be modelled as a- equivale-t ‘compressio- o-lB’ strut i- the buildi-g modelǤ Rigid joi-ts co--ect the beams a-d colum-sǡ but pi- joi-ts co--ect the equivale-t struts to the beamǦtoǦcolum- ju-ctio-sǤ The le-gth of the strut is give- bB the diago-al dista-ce (d) of the pa-el a-d its thick-ess is equal to the thick-ess of the i-fill wallǤ The elastic modulus of the strut is equated to the elastic modulus of maso-rB (E)Ǥ Smith (1966) proposed a formula to calculate the width of strut based o- the relative stiff-ess of the frame aSHEARAs ca- be see- from the tables 1 Ƭ 2 (model II to V) a-d figures 5 to 8 the be-di-g mome-ts a-d shear forces (stre-gth) dema-ds are severelB higher for the grou-d storeB colum-s with respect to first storeB colum-sǡ i- case ANALYSISFollowi-g five models are a-alBCed usi-g respo-se spectrum a-alBsis – Model Iǣ Bare frame model (rei-forced co-crete frame taki-g i-fill maso-rB weightǡ -eglecti-g effect of stiff-ess)Ǥ Model IIǣ Buildi-g with stro-g i-fill (effect of stiff-ess is also co-sidered i- additio- to taki-g weight of i-fill)Ǥ Model IIIǣ Buildi-g with stro-g i-fill havi-g ope-i-gs (model II with ope-i-gs at certai- pa-els)Ǥ Model IVǣ Buildi-g with weak i-fill (effect of stiff-ess is also co-sidered i- additio- to taki-g weight of i-fill)Ǥ Model Vǣ Buildi-g with weak i-fill havi-g ope-i-gs (model IV with ope-i-gs at certai- pa-els)Ǥ Figure 2ǣ Model Iǣ Bare frame (a) Fro-t elevatio- Figure 3ǣ Model II Ƭ IV – I-filled frames (a) Fro-t elevatio- of 2Ǥ5 as give- i- the I-dia- Sta-dard IS 1893ǣ2002 for desig- of a mid rise ope- grou-d storeB buildi-g a-d to assess the i-flue-ce of varBi-g the i-fill arra-geme-ts o- the a-alBsis results bB taki-g various combi-atio-s of i-fill thick-essǡ stre-gthǡ modulus of elasticitB a-d ope-i-gsǤ For the studB five differe-t models of a siA storeB buildi-g are co-sideredǤ The buildi-g has five baBs i- X directio- a-d four baBs i- Y directio- with the pla- dime-sio- 22Ǥ5 m έ 14Ǥ4 m a-d a storeB height of 3Ǥ5 m each i- all the floors a-d depth of fou-datio- take- as 1Ǥ5 mǤ The baB width alo-g lo-gitudi-al directio- is 4Ǥ5m a-d alo-g tra-sverse directio- is 3Ǥ6mǤ The buildi-g is kept sBmmetric i- both orthogo-al directio-s i- pla- to avoid torsio-al respo-se u-der lateral forceǤ The colum- is kept square a-d siCe of the colum- is kept same throughout the height of the structure to keep the discussio- focused o-lB o- the soft first storeB effect without distracted bB the issues like orie-tatio- of colum-Ǥ The buildi-g is co-sidered to be located i- seismic Co-e IV a-d i-te-ded for reside-tial useǤ MǦ25 grade of co-crete a-d FeǦ415 grade of rei-forci-g steel are used for all the frame models used i- this studBǤ The u-it weights of co-crete a-d maso-rB are take- as 25Ǥ0 kN/m a-d 20Ǥ0 respectivelBǤ The modulus of elasticitB of the bricks fou-d i- I-dia varies from 350 MPa to 5000 MPaǤ To represe-t the eAtreme cases of stro-g a-d weak i-fill walls 2 combi-atio-s of i-fill walls are co-sidered for modelli-gǤ The thicker wall of 230mm thick-ess is combi-ed with stro-g i-fill wall havi-g E α 5000 MPa a-d thi--er wall of 115mm thick-ess is combi-ed with weak i-fill wall havi-g E α 350 MPaǤ The poiso- ratio of co-crete is 0Ǥ2 a-d of maso-rB is 0Ǥ15Ǥ Figure 1ǣ Pla- of the structure colum- forces of the grou-d storeB of the give- midǦrise ope- grou-d storeB buildi-gǤ It is fou-d that the i-fill pa-els itherebB i-creasi-g the forcesǡ displaceme-tǡ drift a-d ductilitB dema-d i- the soft grou-d storeBǤ This could become the cause of failure of ope- grou-d storeB buildi-gs duri-g earthquakeǤ TERMS: Ope- grou-d storeBǡ maso-rB i-fill wallsǡ -o-Ǧstructural eleme-tǡ bare frameǡ i-fill stiff-essǤ Rei-forced co-crete framed buildi-gs have become commo- form of co-structio- i- urba- a-d semi urba- areas arou-d the world which is maso-rB i-fillǤ Numerous such buildi-gs co-structed i- rece-t times have a special aspect Ǧ the grou-d storeB is left ope-ǡ which mea-s the colum-s i- the grou-d storeB do -ot have a-B partitio- walls betwee- themǤ These tBpes of buildi-gs havi-g -o i-fill maso-rB walls i- grou-d storeBǡ but havi-g i-fill walls i- all the upper storeBsǡ are called as ‘Ope- Grou-d StoreB (OGS) Buildi-gs’Ǥ This ope- grou-d storeB buildi-g is also termed as buildi-g with ‘Soft StoreB at There is sig-ifica-t adva-tage of such tBpe of buildi-g fu-ctio-allB but whe- seismic performa-ce poi-t of view such buildi-g is co-sidered it is fou-d to have i-creased vul-erabilitBǤ The ope- grou-d storeB buildi-gs are ge-erallB desig-ed as framed structures without regard to structural co-tributio- of maso-rB i-fill wallsǤ The prese-ce of i-fill walls i- all the upper stories eAcept i- the grou-d storeB makes the upper stories much stiffer as compared to the ope- grou-d storeBǤ Thus the upper stories move almost together as a si-gle block a-d most of the horiCo-tal displaceme-t of the buildi-g occurs i- the soft grou-d storeB itself a-d he-ce the grou-d storeB colum-s are heavilB stressedǤ IS 1893 (2002) recomme-ds a mag-ificatio- factor of 2Ǥ5 to be applied o- be-di-g mome-ts a-d shear forces i- the colum-s of grou-d storeB calculated for the bare frame u-der The salie-t objectives of the prese-t studB have bee- to studB the effect of i-fill stre-gth a-d stiff-ess i- the seismic a-alBsis of ope- grou-d storeB (OGS) buildi-gsǡ to check the applicabilitB of the multiplicatio- factor WITHSOFTSHARMA,Dr.GARGPost Graduate Stude-tǡ Civil E-gi-eeri-g Departme-tǡ MANITǡ Bhodharmesh2405@gmailǤcom Associate Professorǡ Civil E-gi-eeri-g Departme-tǡ MANITǡ Bhopalǡ MadhBa Pradeshǡ Assista-t Professorǡ Civil E-gi-eeri-g Departme-tǡ MANITǡ Bhopalǡ MadhBa Pradeshǡ vivek_garg5@BahooǤcoǤi- Ma-B urba- multi storeB buildi-gs i- I-dia todaB have ope- grou-d storB as a- u-avoidable aspectǡ basicallB to ge-erate parki-g or receptio- lobbiesǤ The upper storeBs have brick i-filled wall pa-els with various ope-i-g perce-tage i- themǤ These tBpes of buildi-gs are -ot desirable i- seismicallB active areas because various vertical irregularities are i-duced i- such buildi-gs which have performed co-siste-tlB poor duri-g past earthquakesǤ It has bee- k-ow- si-ce lo-g time that maso-rB i-fill walls affect the stre-gth a-d stiff-ess of i-filled framed structuresǤ I-fill walls are ge-erallB see- as a -o-Ǧstructural eleme-t a-d their effect is -eglected bB ig-ori-g the stiff-ess of the i-fill wall duri-g the modelli-g phase of the structure (a-alBsed as a ‘li-ear bare frame’) leadi-g to substa-tial i-accuracB i- obtai-i-g the actual seismic respo-se of framed structuresǤ The objective of the paper is to check the applicabilitB of the multiplicatio- factor of 2Ǥ5 for the give- buildi-g of mid height a-d to studB the i-flue-ce of i-fill stre-gth a-d stiff-ess i- the seismic a-alBsis of a mid rise ope- grou-d storeB buildi-gǤ A rei-forced co-crete framed buildi-g (GΪ5) with ope- grou-d storeB located i- Seismic Zo-eǦIV is co-sidered for this studBǤ This buildi-g is a-alBCed for two differe-t casesǣ (a) co-sideri-g both i-fill mass a-d i-fill stiff-ess a-d (b) co-sideri-g i-fill mass but without co-sideri-g i-fill stiff-ess bB respo-se spectrum a-alBsis methodǤ The result shows that the effect of i-fill’s stiff-ess o- structural respo-se is sig-ifica-t u-der lateral loadsǤ The mag-ificatio- factor of 2Ǥ5 is high to be multiplied to