WITHSOFTSHARMA,Dr.GARG - PDF document

WITHSOFTSHARMA,Dr.GARG Assoc‹ate Professor, C‹v‹Ž E-g‹-eer‹-g Departe-t, MANT, BŠopaŽ, MadŠ›a PradesŠ, Ass‹sta-t Professor, C‹v‹Ž E-g‹-eer‹-g Departe-t, MANT, BŠopaŽ, MadŠ›a PradesŠ, Ma-› urba- uŽt‹ store› bu‹Žd‹-gs ‹- -d‹a toda› Šave ope- grou-d stor› as a- u-avo‹dabŽe aspect, bas‹caŽŽ› to ge-erate par‹-g or recept‹o- Žobb‹es. TŠe upper coŽu- forces of tŠe grou-d store› of tŠe g‹ve- ‹d‐r‹se ope- grou-d store› bu‹Žd‹-g. t ‹s fou-d tŠat tŠe ‹-f‹ŽŽ pa-eŽs ‹tŠereb› ‹-creas‹-g tŠe forces, d‹spŽacee-t, dr‹ft a-d duct‹Ž‹t› dea-d ‹- tŠe soft grou-d store›. TŠ‹s couŽd becoe tŠe cause of fa‹Žure of ope- grou-d store› bu‹Žd‹-gs dur‹-g eartŠquae. TERMS: Ope- grou-d store›, aso-r› ‹-f‹ŽŽ waŽŽs, -o-‐structuraŽ eŽee-t, bare frae, ‹-f‹ŽŽ st‹ff-ess. Re‹-forced co-crete fraed bu‹Žd‹-gs Šave becoe coo- for of co-struct‹o- ‹- urba- a-d se‹ urba- areas arou-d tŠe worŽd wŠ‹cŠ ‹s aso-r› ‹-f‹ŽŽ. Nuerous sucŠ bu‹Žd‹-gs co-structed ‹- rece-t t‹es Šave a spec‹aŽ aspect ‐ tŠe grou-d store› ‹s Žeft ope-, wŠ‹cŠ ea-s tŠe coŽu-s ‹- tŠe grou-d store› do -ot Šave a-› part‹t‹o- waŽŽs betwee- tŠe. TŠese t›pes of bu‹Žd‹-gs Šav‹-g -o ‹-f‹ŽŽ aso-r› waŽŽs ‹- grou-d store›, but Šav‹-g ‹-f‹ŽŽ waŽŽs ‹- aŽŽ tŠe upper store›s, are caŽŽed as ǮOpe- rou-d Store› ȋO SȌ Bu‹Žd‹-gsǯ. TŠ‹s ope- grou-d store› bu‹Žd‹-g ‹s aŽso tered as bu‹Žd‹-g w‹tŠ ǮSoft Store› at TŠere ‹s s‹g-‹f‹ca-t adva-tage of sucŠ t›pe of bu‹Žd‹-g fu-ct‹o-aŽŽ› but wŠe- se‹s‹c perfora-ce po‹-t of v‹ew sucŠ bu‹Žd‹-g ‹s co-s‹dered ‹t ‹s fou-d to Šave ‹-creased vuŽ-erab‹Ž‹t›. TŠe ope- grou-d store› bu‹Žd‹-gs are ge-eraŽŽ› des‹g-ed as fraed structures w‹tŠout regard to structuraŽ co-tr‹but‹o- of aso-r› ‹-f‹ŽŽ waŽŽs. TŠe prese-ce of ‹-f‹ŽŽ waŽŽs ‹- aŽŽ tŠe upper stor‹es ešcept ‹- tŠe grou-d store› aes tŠe upper stor‹es ucŠ st‹ffer as copared to tŠe ope- grou-d store›. TŠus tŠe upper stor‹es ove aŽost togetŠer as a s‹-gŽe bŽoc a-d ost of tŠe Šor‹œo-taŽ d‹spŽacee-t of tŠe bu‹Žd‹-g occurs ‹- tŠe soft grou-d store› ‹tseŽf a-d Še-ce tŠe grou-d store› coŽu-s are Šeav‹Ž› stressed. S 1ͺͻ3 ȋ2002Ȍ recoe-ds a ag-‹f‹cat‹o- factor of 2.5 to be appŽ‹ed o- be-d‹-g oe-ts a-d sŠear forces ‹- tŠe coŽu-s of grou-d store› caŽcuŽated for tŠe bare frae u-der TŠe saŽ‹e-t obŒect‹ves of tŠe prese-t stud› Šave bee- to stud› tŠe effect of ‹-f‹ŽŽ stre-gtŠ a-d st‹ff-ess ‹- tŠe se‹s‹c a-aŽ›s‹s of ope- grou-d store› ȋO SȌ bu‹Žd‹-gs, to cŠec tŠe appŽ‹cab‹Ž‹t› of tŠe uŽt‹pŽ‹cat‹o- factor of 2.5 as g‹ve- ‹- tŠe -d‹a- Sta-dard S 1ͺͻ3:2002 for des‹g- of a ‹d r‹se ope- grou-d store› bu‹Žd‹-g a-d to assess tŠe ‹-fŽue-ce of var›‹-g tŠe ‹-f‹ŽŽ arra-gee-ts o- tŠe a-aŽ›s‹s resuŽts b› ta‹-g var‹ous cob‹-at‹o-s of ‹-f‹ŽŽ tŠ‹c-ess, stre-gtŠ, oduŽus of eŽast‹c‹t› a-d ope-‹-gs. For tŠe stud› f‹ve d‹ffere-t odeŽs of a s‹š store› bu‹Žd‹-g are co-s‹dered. TŠe bu‹Žd‹-g Šas f‹ve ba›s ‹-  d‹rect‹o- a-d four ba›s ‹-  d‹rect‹o- w‹tŠ tŠe pŽa- d‹e-s‹o- 22.5  × 14.4  a-d a store› Še‹gŠt of 3.5  eacŠ ‹- aŽŽ tŠe fŽoors a-d deptŠ of fou-dat‹o- tae- as 1.5 . TŠe ba› w‹dtŠ aŽo-g Žo-g‹tud‹-aŽ d‹rect‹o- ‹s 4.5 a-d aŽo-g tra-sverse d‹rect‹o- ‹s 3.6. TŠe bu‹Žd‹-g ‹s ept s›etr‹c ‹- botŠ ortŠogo-aŽ d‹rect‹o-s ‹- pŽa- to avo‹d tors‹o-aŽ respo-se u-der ŽateraŽ force. TŠe coŽu- ‹s ept square a-d s‹œe of tŠe coŽu- ‹s ept sae tŠrougŠout tŠe Še‹gŠt of tŠe structure to eep tŠe d‹scuss‹o- focused o-Ž› o- tŠe soft f‹rst store› effect w‹tŠout d‹stracted b› tŠe ‹ssues Ž‹e or‹e-tat‹o- of coŽu-. TŠe bu‹Žd‹-g ‹s co-s‹dered to be Žocated ‹- se‹s‹c œo-e V a-d ‹-te-ded for res‹de-t‹aŽ use. M‐25 grade of co-crete a-d Fe‐415 grade of re‹-forc‹-g steeŽ are used for aŽŽ tŠe frae odeŽs used ‹- tŠ‹s stud›. TŠe u-‹t we‹gŠts of co-crete a-d aso-r› are tae- as 25.0 N/ a-d 20.0 respect‹veŽ›. TŠe oduŽus of eŽast‹c‹t› of tŠe br‹cs fou-d ‹- -d‹a var‹es fro 350 MPa to 5000 MPa. To represe-t tŠe eštree cases of stro-g a-d wea ‹-f‹ŽŽ waŽŽs 2 cob‹-at‹o-s of ‹-f‹ŽŽ waŽŽs are co-s‹dered for odeŽŽ‹-g. TŠe tŠ‹cer waŽŽ of 230 tŠ‹c-ess ‹s cob‹-ed w‹tŠ stro-g ‹-f‹ŽŽ waŽŽ Šav‹-g E = 5000 MPa a-d tŠ‹--er waŽŽ of 115 tŠ‹c-ess ‹s cob‹-ed w‹tŠ wea ‹-f‹ŽŽ waŽŽ Šav‹-g E = 350 MPa. TŠe po‹so- rat‹o of co-crete ‹s 0.2 a-d of aso-r› ‹s 0.15. F‹gure 1: PŽa- of tŠe structure ANALYSISFoŽŽow‹-g f‹ve odeŽs are a-aŽ›œed us‹-g respo-se spectru a-aŽ›s‹s – ModeŽ : Bare frae odeŽ ȋre‹-forced co-crete frae ta‹-g ‹-f‹ŽŽ aso-r› we‹gŠt, -egŽect‹-g effect of st‹ff-essȌ. ModeŽ : Bu‹Žd‹-g w‹tŠ stro-g ‹-f‹ŽŽ ȋeffect of st‹ff-ess ‹s aŽso co-s‹dered ‹- add‹t‹o- to ta‹-g we‹gŠt of ‹-f‹ŽŽȌ. ModeŽ : Bu‹Žd‹-g w‹tŠ stro-g ‹-f‹ŽŽ Šav‹-g ope-‹-gs ȋodeŽ  w‹tŠ ope-‹-gs at certa‹- pa-eŽsȌ. ModeŽ V: Bu‹Žd‹-g w‹tŠ wea ‹-f‹ŽŽ ȋeffect of st‹ff-ess ‹s aŽso co-s‹dered ‹- add‹t‹o- to ta‹-g we‹gŠt of ‹-f‹ŽŽȌ. ModeŽ V: Bu‹Žd‹-g w‹tŠ wea ‹-f‹ŽŽ Šav‹-g ope-‹-gs ȋodeŽ V w‹tŠ ope-‹-gs at certa‹- pa-eŽsȌ. F‹gure 2: ModeŽ : Bare frae ȋaȌ Fro-t eŽevat‹o- F‹gure 3: ModeŽ  & V – -f‹ŽŽed fraes ȋaȌ Fro-t eŽevat‹o- ȋbȌ S‹de eŽevat‹o- F‹gure 4: ModeŽ  & V – -f‹ŽŽed fraes w‹tŠ ope-‹-gs FRAMEINFILLTŠe structuraŽ ebers are odeŽŽed w‹tŠ tŠe a‹d of coerc‹aŽ software ETABS v ͻ.7.1 ‹- copŽ‹a-ce w‹tŠ tŠe codes S 456‐2000 a-d S 1ͺͻ3‐2002. TŠe frae ebers are odeŽŽed w‹tŠ r‹g‹d e-d co-d‹t‹o-s. TŠe fŽoor sŽabs were assued to act as d‹apŠrags, wŠ‹cŠ e-sure ‹-tegraŽ act‹o- of aŽŽ tŠe ŽateraŽ Žoad‐res‹st‹-g eŽee-ts. TŠe fŽoor f‹-‹sŠ o- tŠe fŽoors ‹s tae- to be 1.0 N/. TŠe Ž‹ve Žoad o- fŽoor ‹s tae- as 3.0 N/ a-d tŠat o- tŠe roof to be 1.5 N/. - se‹s‹c we‹gŠt caŽcuŽat‹o-s, 25 % of tŠe fŽoor Ž‹ve Žoads are co-s‹dered ‹- tŠe a-aŽ›s‹s. For a- ‹-f‹ŽŽ waŽŽ Žocated ‹- a ŽateraŽ Žoad‐res‹st‹-g frae, tŠe st‹ff-ess a-d stre-gtŠ co-tr‹but‹o- of tŠe ‹-f‹ŽŽ Šas to be co-s‹dered. No-‐‹-tegraŽ ‹-f‹ŽŽ waŽŽs subŒected to ŽateraŽ Žoad beŠave Ž‹e d‹ago-aŽ struts. TŠus a- ‹-f‹ŽŽ waŽŽ ca- be odeŽŽed as a- equ‹vaŽe-t Ǯcopress‹o- o-Ž›ǯ strut ‹- tŠe bu‹Žd‹-g odeŽ. R‹g‹d Œo‹-ts co--ect tŠe beas a-d coŽu-s, but p‹- Œo‹-ts co--ect tŠe equ‹vaŽe-t struts to tŠe bea‐to‐coŽu- Œu-ct‹o-s. TŠe Že-gtŠ of tŠe strut ‹s g‹ve- b› tŠe d‹ago-aŽ d‹sta-ce ȋdȌ of tŠe pa-eŽ a-d ‹ts tŠ‹c-ess ‹s equaŽ to tŠe tŠ‹c-ess of tŠe ‹-f‹ŽŽ waŽŽ. TŠe eŽast‹c oduŽus of tŠe strut ‹s equated to tŠe eŽast‹c oduŽus of aso-r› ȋEȌ. S‹tŠ ȋ1ͻ66Ȍ proposed a foruŽa to caŽcuŽate tŠe w‹dtŠ of strut based o- tŠe reŽat‹ve st‹ff-ess of tŠe frae aSHEARAs ca- be see- fro tŠe tabŽes 1 & 2 ȋodeŽ  to VȌ a-d f‹gures 5 to ͺ tŠe be-d‹-g oe-ts a-d sŠear forces ȋstre-gtŠȌ dea-ds are severeŽ› Š‹gŠer for tŠe grou-d store› coŽu-s w‹tŠ respect to f‹rst store› coŽu-s, ‹- case of tŠe soft grou-d store› bu‹Žd‹-gs wŠe- tŠe› are a-aŽ›œed b› co-s‹der‹-g ‹-f‹ŽŽ as structuraŽ copo-e-t ta‹-g ‹-to co-s‹derat‹o- tŠe‹r st‹ff-ess aŽso w‹tŠ tŠe‹r we‹gŠt. TŠe ‹-troduct‹o- of waŽŽs ‹- tŠe f‹rst store› ȋodeŽ  to VȌ reduces tŠe force ‹- tŠe f‹rst store› coŽu-s. - odeŽ , tŠe be-d‹-g oe-t a-d sŠear forces are tŠe aš‹u as copared to otŠer odeŽs, as tŠere ‹s -o effect of ‹-f‹ŽŽ waŽŽs co-s‹dered ‹- tŠe‹r a-aŽ›s‹s wŠ‹cŠ sŠows tŠe force dea-ds depe-ds upo- tŠe st‹ff-ess of tŠe ebers. AŽso tŠe forces ‹- tŠe f‹rst store› coŽu-s of odeŽ  are aŽost equaŽ to tŠe forces ‹- tŠe grou-d store› coŽu-s or eve- ore for sŠear forces wŠ‹cŠ ‹s drast‹caŽŽ› oppos‹te beŠav‹our as copared to tŠe otŠer odeŽs. TŠerefore tŠe ‹porta-ce of odeŽŽ‹-g a-d co-s‹der‹-g tŠe ‹-f‹ŽŽ waŽŽs as structuraŽ copo-e-t a-d aŽso tŠe descr‹pt‹o- of ‹-f‹ŽŽ ater‹aŽs, tŠe‹r t›pe, stre-gtŠ a-d tŠe‹r eŽast‹c oduŽus def‹-‹t‹o- ‹s reaŽ‹œed Šere. TabŽe 1: Maš‹u be-d‹-g oe-t ‹- grou-d store› a-d f‹rst store› coŽu-s Bending(kNm) Longitudinal Transverse StoreyStoreyStoreyStorey 7ͻ7477 73 ͺ64ͺͻ0 40 ͺ251ͺ4 36 702771 2ͺ 66266ͺ 2ͺ F‹gure 5: Copar‹so- of aš‹u be-d‹-g oe-ts ‹- Žo-g‹tud‹-aŽ d‹rect‹o- : Copar‹so- of aš‹u be-d‹-g oe-ts ‹- tra-sverse Maš‹u sŠear force ‹- grou-d store› a-d f‹ShearForce(kN) Longitudinal Transverse StoreyStoreyStoreyStorey 40 42 40 41 51 21 52 15 4ͻ 21 51 14 3ͻ 15 40 1ͺ 36153ͺ 1ͺ : Copar‹so- of aš‹u sŠear force ‹- Žo-g‹tud‹-aŽ d‹rect‹o- : Copar‹so- of aš‹u sŠear force ‹- tra-sverse d‹rect‹o- LATERAL ‹- Žo-g‹tud‹-aŽ d‹rect‹o- 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 F‹gure ͻ: D‹spŽacee-t prof‹Že aŽo-g Žo-g‹tud‹-aŽ d‹rect‹o- TabŽe ‐4: Store› dr‹ft ȋ‹- Ȍ ‹- Žo-g‹tud‹-aŽ d‹rect‹o- 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 F‹gure 10: Store› dr‹fts TŠe d‹spŽacee-t of tŠe odeŽ  at aŽŽ tŠe fŽoors ‹s tŠe aš‹u w‹tŠ respect to tŠat of aŽŽ tŠe otŠer odeŽs. TŠere ‹s a Šuge d‹ffere-ce betwee- tŠe d‹spŽacee-t vaŽues of odeŽ  a-d aŽŽ otŠer odeŽs. TŠ‹s gap of d‹ffere-ce ‹s ‹-creas‹-g u-‹forŽ› w‹tŠ tŠe ‹-crease ‹- tŠe store› ŽeveŽ. AŽso tŠe d‹spŽacee-t of odeŽ V & V ‹s ore tŠa- tŠe d‹spŽacee-t of odeŽ  &  tŠrougŠout tŠe fŽoors. TŠe d‹spŽacee-t of odeŽ  ‹s of sucŠ aou-t because tŠere ‹s -o ŽateraŽ st‹ff-ess prov‹ded to tŠe structure b› tŠe ‹-f‹ŽŽ waŽŽ. As ca- be see- fro f‹gures a-d tabŽes for store› dr‹ft, tŠe store› dr‹ft prof‹Že of odeŽ  ‹s sootŠ tŠrougŠout wŠereas for odeŽ  to V tŠe store› dr‹ft cŠa-ges abruptŽ› fro grou-d store› to f‹rst store›. TŠ‹s sudde- cŠa-ge of sŽope of store› dr‹ft prof‹Že aŽo-g prof‹Že of eacŠ odeŽ s‹g-‹f‹es st‹ff-ess ‹rreguŽar‹t› betwee- soft store› a-d ‹-f‹ŽŽed store›, e-cou-tered because of odeŽŽ‹-g st‹ff-ess of ‹-f‹ŽŽ waŽŽ for soft grou-d store› bu‹Žd‹-gs. SucŠ st‹ff-ess ‹rreguŽar‹t› of soft grou-d store› bu‹Žd‹-gs ‹s cr‹t‹caŽ fro fa‹Žure po‹-t of v‹ew wŠe- subŒected to eartŠquae forces because of resebŽa-ce of ‹ts beŠav‹our w‹tŠ tŠe beŠav‹our of ‹-verted pe-duŽu. TŠe upper store›s ove togetŠer as a s‹-gŽe bŽoc a-d ost of tŠe Šor‹œo-taŽ deforat‹o- of tŠe bu‹Žd‹-g occurs ‹- tŠe soft grou-d store› ‹tseŽf. TabŽe 5 ‹-d‹cates tŠat tŠe ag-‹f‹cat‹o- factor vaŽues ‹s fou-d to var› betwee- 0.ͺͺ to 1.17 for tŠe be-d‹-g oe-t a-d for sŠear forces betwee- 0.ͻ5 to 1.33 ‹- tŠe grou-d store› coŽu-s of tŠe odeŽs  to V ‹- copar‹so- to tŠe correspo-d‹-g vaŽues of be-d‹-g oe-t a-d sŠear force ‹- tŠe grou-d TabŽe 5: Mag-‹f‹cat‹o- factors for be-d‹-g oe-t a-d sŠear force Maš‹u BM ‹- grou-d store› ȋNȌ Ešter‹or CoŽu- 76ͺͻ71 6ͺ CoŽu- 77ͻ071 6ͺ Maš‹u sŠear force ‹- grou-d store› ȋNȌ Ešter‹or CoŽu- 3ͻ5240 3ͺ CoŽu- 405240 3ͺ # Mag-‹f‹cat‹o- factor vaŽues for be-d‹-g oe-t & sŠear force obta‹-ed b› d‹v‹d‹-g w‹tŠ tŠe correspo-d‹-g vaŽues for tŠe bare frae. TŠe foŽŽow‹-g are tŠe a‹- f‹-d‹-gs of tŠe prese-t stud› – TŠe structuraŽ eber forces, deforat‹o-s do var› w‹tŠ tŠe d‹ffere-t paraeters assoc‹ated w‹tŠ tŠe ‹-f‹ŽŽ waŽŽs. SucŠ var‹at‹o-s are -ot co-s‹dered ‹- curre-t codes a-d tŠus tŠe gu‹da-ce for tŠe des‹g- of bu‹Žd‹-gs Šav‹-g ‹-f‹ŽŽ waŽŽs ‹s ‹-copŽete a-d spec‹f‹caŽŽ› for bu‹Žd‹-gs w‹tŠ soft grou-d store› ‹t ‹s ‹perat‹ve to Šave des‹g- gu‹deŽ‹-es ‹- deta‹Ž. -f‹ŽŽ pa-eŽs ‹-creases tŠe st‹ff-ess of tŠe structure a-d tŠe ‹-crease ‹- tŠe ope-‹-g perce-tage Žeads to a decrease o- tŠe ŽateraŽ st‹ff-ess of ‹-f‹ŽŽed frae. e-ce beŠav‹our of bu‹Žd‹-g var‹es w‹tŠ tŠe cŠa-ge ‹- ‹-f‹ŽŽ arra-gee-ts. TŠ‹s ‹-d‹cates tŠat odeŽŽ‹-g of re‹-forced co-crete frae bu‹Žd‹-g w‹tŠout ‹-f‹ŽŽ waŽŽ ȋpa-eŽȌ or bare frae odeŽ a› -ot be appropr‹ate for tŠe a-aŽ›s‹s. TŠe a-aŽ›ses resuŽt sŠows tŠat coŽu- forces at tŠe grou-d store› ‹-creases for tŠe prese-ce of ‹-f‹ŽŽ waŽŽ ‹- tŠe upper store›s. But des‹g- force ag-‹f‹cat‹o- factor fou-d to be ucŠ Žesser tŠa- 2.5. TŠ‹s ‹s part‹cuŽarŽ› true for ‹d‐r‹se ope- grou-d store› bu‹Žd‹-gs. t ‹s see- fro respo-se spectru a-aŽ›s‹s tŠat tŠe ag-‹f‹cat‹o- factor decreases wŠe- tŠe st‹ff-ess of ‹-f‹ŽŽ pa-eŽs are decreased e‹tŠer b› reduc‹-g ‹-f‹ŽŽ stre-gtŠ ȋtŠ‹c-ess a-d oduŽus of eŽast‹c‹t›Ȍ or b› prov‹d‹-g ope-‹-gs ‹- tŠe ‹-f‹ŽŽ Še- a bare frae odeŽ ‹s subŒected to ŽateraŽ Žoad, ass of eacŠ fŽoor acts ‹-depe-de-tŽ› resuŽt‹-g eacŠ fŽoor to dr‹ft w‹tŠ respect to adŒace-t fŽoors. TŠus tŠe bu‹Žd‹-g frae beŠaves ‹- tŠe fŽeš‹bŽe a--er caus‹-g d‹str‹but‹o- of Šor‹œo-taŽ sŠear across fŽoors. - prese-ce of ‹-f‹ŽŽ waŽŽ ȋpa-eŽȌ, tŠe reŽat‹ve dr‹ft betwee- adŒace-t fŽoors ‹s restr‹cted caus‹-g ass of tŠe upper fŽoors to act togetŠer as a s‹-gŽe ass. - sucŠ case, tŠe totaŽ ‹-ert‹a of tŠe aŽŽ upper fŽoors causes a s‹g-‹f‹ca-t ‹-crease ‹- Šor‹œo-taŽ sŠear force at base or ‹- tŠe grou-d fŽoor coŽu-s. S‹‹ŽarŽ› ‹-creases tŠe be-d‹-g oe-t Fro tŠe prese-t resuŽts ‹t ‹s fou-d tŠat, ŽateraŽ d‹spŽacee-t ‹s ver› Žarge ‹- case of bare frae as copare to tŠat of ‹-f‹ŽŽed fraes. f tŠe effect of ‹-f‹ŽŽ waŽŽ ‹s co-s‹dered tŠe- tŠe defŽect‹o- Šas reduced drast‹caŽŽ›. TŠe prese-ce of waŽŽs ‹- upper store›s aes tŠe ucŠ st‹ffer tŠa- ope- grou-d store›. e-ce tŠe upper store› ove aŽost togetŠer as a s‹-gŽe bŽoc a-d ost of tŠe Šor‹œo-taŽ d‹spŽacee-t of tŠe bu‹Žd‹-g occurs ‹- tŠe soft grou-d store› ‹tseŽf. [1]. AgarwaŽ P. a-d SŠr‹Ša-de M. ȋ2006Ȍ. EartŠquae res‹sta-t des‹g- of structures. P ear-‹-g Pvt. td., New [2]. ArŽear .N., a‹- S. . a-d Murt› ȋ1ͻͻ7Ȍ. Se‹s‹c respo-se of RC fraes bu‹Žd‹-gs w‹tŠ soft f‹rst store›s. Proceed‹-gs of CBR goŽde- Œub‹Žee co-fere-ce o- -aturaŽ Šaœards ‹- urba- [3]. Dav‹s R., Me-o- D. a-d Prasad A. M. ȋ200ͺȌ. EvaŽuat‹o- of ag-‹f‹cat‹o- factors for ope- grou-d store› bu‹Žd‹-gs us‹-g -o-Ž‹-ear a-aŽ›ses. TŠe 14orŽd Co-fere-ce o- EartŠquae E-g‹-eer‹-g, Be‹Œ‹-g, CŠ‹-a. [4]. ETABS -o-Ž‹-ear vers‹o- ͻ.7.1. Ešte-ded TŠree D‹e-s‹o-aŽ A-aŽ›s‹s of Bu‹Žd‹-g S›stes, Userǯs Ma-uaŽ. Coputers a-d Structures, -c., BereŽe›, CaŽ‹for-‹a, USA. [5]. S 1ͺͻ3 Part 1 ȋ2002Ȍ. Cr‹ter‹a for EartŠquae Res‹sta-t Des‹g- of Structures. Bureau of -d‹a- Sta-dards, [6]. S 456 ȋ2000Ȍ.PŽa‹- a-d re‹-forced co-crete: Code of pract‹ce. Bureau of -d‹a- Sta-dards, New DeŽŠ‹. [7]. Subraa-‹a- N. ȋ2004Ȍ. D‹scuss‹o- o- se‹s‹c perfora-ce of co-ve-t‹o-aŽ uŽt‹‐store› bu‹Žd‹-g w‹tŠ ope- grou-d fŽoors for veŠ‹cuŽar par‹-g b› a-‹tar a-d a-‹tar. TŠe -d‹a- Co-crete our-aŽ. 7ͺ, 11‐13. DharmeshVijaywargiya,Post raduate Stude-t, C‹v‹Ž E-g‹-eer‹-g Departe-t MANT, BŠopaŽ, MadŠ›a PradesŠ, -d‹a AbhaySharma,Assoc‹ate Professor, C‹v‹Ž E-g‹-eer‹-g Departe-t MANT, BŠopaŽ, MadŠ›a PradesŠ, -d‹a VivekAss‹sta-t Professor, C‹v‹Ž E-g‹-eer‹-g Departe-t MANT, BŠopaŽ, MadŠ›a PradesŠ, -d‹a 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