THE SIGNIFICANCE OF PROVIDING OF SHEAR WALLS IN TALL BUILDINGS

Transcription

1 THE SIGNIFICANCE OF PROVIDING OF SHEAR WALLS IN TALL BUILDINGS 1 V.Klpn, 2 N.R.Sngeeth, 3 M.Sheik Mohmed 1 Assistnt Professor, Civil Engineering Deprtment, AlimMuhmmedSlegh College of Engineering, Muthpudupet, Avdi-IAF, Chenni, Tmil Ndu, Indi 2 P.G Student (M.E Struturl engineering),sreessth Institute of Engineering nd Tehnology, Chenni, Tmil Ndu,Indi 3 Assistnt Engineer, Nrd& Rurl Rods, Tmil Ndu Highwys Deprtment, Snkrnkovil, Tirunelveli, TmilNdu,Indi Astrt: Tll uildings re the tll strutures widely used ll round the world. These tll strutures eliminte the spe required for uildings in the horizontl diretion. The struturl nd onstrution fetures differ onsiderly when ompred to low risestrutures. Severe struturl dmge suffered y severl modern uildings like tll strutures during erthqukes, whih loses its strength nd stiffness of uilding. To overome from the lterl loding filures, strong nd stiff lod resisting system is essentil in tll uildings. This pper dels with the importne of providing of sher wlls in resisting lterl lods in tll uildings. Experimentl nd nlytil studies re rried out to ssess the uses of sher wll in struturl sfety, servieility nd stility. An effetive lterl lod resisting system like moment resisting frme, ring frme nd ring with sher wll frme is used in this study. The lterl storey drift is noted nd ompred with the nlytil results with the help of E-TABS. Keyword: frme, lterl fore, model, sher wll, stiffness, swy, x ring, tll uilding. 1. INTRODUCTION Tll uildings or skysrpers re the tllest strutures whih re hving normlly more thn fourty floors whih re ment to provision for minly ommeril nd residentil purpose. These tll strutures re generlly onstruted t present with either omposite or steel frme. The rhiteturl nd struturl spets vry onsiderly. The onstrution proedures lso hnge due to its height nd omplexity. The design of tll uildings should e done with utmost re s ompred with low rise uildings. In the design stge of tll uildings lterl lods nothing ut horizontl lods oupy importnt role. The lterl fores ommonly re wind nd seismi fore or erthquke fore. The lterl lods led to severe struturl dmge like grvity lods in tll uildings s ompred with the low rise uildings. High rise uildings design involves omplete understnding of struturl omponents of tll uildings sujeted to severl ftors rhiteturl nd other thn ivil works. Normlly the tll strutures usully get ffeted y lterl fores ting on it. Due to the lterl fores the entire tll uilding gets ollpsed nd forms more rks et.the sher wllsresist the dmge used y the lterl fores. 2. SHEAR WALLS Sher wlls or struturl wlls re frequently known for resisting lterl lods. The struturl wlls re mde up of reinfored onrete to inrese the strength of wlls. These wlls re prtiulrly loted lift nd stirse regions to overome virtion nd horizontl sher fore. These wlls re onstruted up to the entire height of struture. By its nme the struturl wlls re lso loted in trnsverse or lterl diretions of uilding to resist lterl fores nmely wind Pge 28

2 nd seismi fores. Some ses, if the lotion of uilding is of highly windy, the struturl wlls n e loted in exterior s well s interior res of uilding. The sher wlls re very stiff in nture euse of reinfored. They re firmly fixed with foundtion nd resist the horizontl lods y vertil ending in nture nd ehve s vertil ntilever wlls. The wll thikness n e vried from 150 mm to 400mm.The lterl lod resisting system is very muh interted with the vertil frming s this omined lod resisting system provides etter lod rrying, resisting nd sfety. Due to its verstility sher wll is provided in tll strutures. 3. LITERATURE REVIEW Struturl frmes re usully filled with infilled wlls nmed s prtitions. Infills hve een generlly onsidered s nonstruturl elements. The presene of infills hs een ignored in most of the urrent seismi odes exept their weight. For finding the importne of the lterl lod resisting systems extensive study is rried out. E.A Godinez-dominguez nd Tenolung (2008) studied the Behviour of moment resisting reinfored onrete onentri red frmes in seismi zones. RC Frme nd Steel ring Frme where experimentlly studied. By the nlysis they hve proved tht the perentge of the lterl sher strength provided for the steel ring system is greter thn the RC moment resisting frmed. Only 50% of the lterl strength is provided y the olumns of the RC moment resisting frmes. H.S Jdhv et l (2014) hd done seismi nlysis of Seven storey uilding with different rings (Digonl, V type, Inverted type nd X type).brings re provided on the peripherl olumns. This struture ws nlysed y using Std prov 8i Softwre. It is found tht X type steel ring hd redued the lterl displement when ompred with the other types of ring. Astneh-Asl.A (2000) studied the ehviour of the steel plte sher wll. He hd sid the usge of steel plte sher wll in the tll uilding. Steel plte sher wlls hve een performing well in the pst erth qukes tht ourred in North Ameri nd Jpn.This pper helped to develop the design offie guidelines nd ode provisions y yli testing of steel sher wll.korkmz-et l hd foused on the msonry infill wlls.he mde study on the three storey RC struture with msonry infill wlls. The erth quke response of the struture ws determined y the non liner nlysis of the SAP2000 Softwre. Push over urves re formed y the softwre nlysis nd storey displement, plsti rottion, reltive storeydisplements re lso otined [3]. 4. ANALYTICAL PROGRAM Even though experimentl work is essentil in every reserh work, ut t tht sme time nlytil studies lso ply ruil role in studying prtiulr phenomenon. Aprt from experimentl work, nlytil work is lso deployed in this study. In order to simulte the results to tll uildings three storey uilding is onsidered in this work. Three ys of uilding whih hs horizontl length of 12 m nd vertil height of 9.6m.A suitle sle ftor is provided to redue the frme dimensions s 1.2mx0.96m. 4.1 Anlysis The nlysis of this three story struture is done y E-ts. Initilly the model of the orresponding struture is reted y ssigning geometril properties nd mteril properties. The nlysis is done for steel frme, X ring steel frme nd sher wll X ring frme. After the ompletion of model, the lod nlysis rried out. The vertillods nothing ut ded nd live lods re omputed using IS 875 prt 1 nd prt 2:1987.In this struture the wind lod intensity ompred with the seismi lod intensity is low. For this the lterl seismi lod is tken for nlysis. In order to redue the dmge, the elow lod omintions hve een mde s per IS 1893 prt 1:2002 1) 1.5(DL + LL),2) 1.2(DL + LL ± EL),3) 1.5(DL ± EL),4)0.9 DL ±1.5EL,5) 1.7(DL + LL),6) 1.7(DL ± EL),7) 1.3(DL + LL ± EL). The mximumdefletion result for worst loding se is given. In this work the nlytil results re pproximtely simulted with the experimentl results. 4.2 Anlytil results In this setion the mximum swy of portl frmes results for mximum loding ondition in ll ses re given. These results re indition of lterl storey drift of portl frmes when they re sujeted to lterl lods. The nlytil deformtionresults of portl frmes re s muh loser to experimentl deformtion. The results re tulted in tle 4.1. Pge 29

3 Tle 4.1: Lterl Swy of the frmes Cse Mximum lterl swy in mm Steel frme 8.5 X ring frme 0.3 Sher wll frme EXPERIMENTAL PROGRAM The im of this experimentl work is to simulte the experimentl results pproximtely to tll uilding. For this three storey uilding is tken.the model of three storey uilding with three ys is frited. The height of the model is 0.96m nd the width is 1.2 m. The dimension of single storey of model y frme is 0.4m x 0.32m. 5.1 Foundtion setup Fig.5: Modeling of sher wll frme in E-ts The floor is well lened for the struturl frme foundtion. The setting out or foundtion mrking of the frme is estlished with the ssist of hlk powder. Then the mrked res re dug t depth of 1.5m nd the width is of 1m nd the length is of 2.5m. The dug surfe is very well lened y pouring wter.the mild steel r of 12 mm dimeter is used for mking vertil frme. In the sme wy, for mking horizontl frme 10 mm dimeter mild steel r is used. Mild steel 8mmdimeter r is used for mking ring frme. The frme is onneted y mens of welding to se plte. The top se plte is well nhored y olts. This top orner nhor olts whih in turn resting on the ottom se plte. The ottom se plte is diretly resting on soil. A suitle leveling ourse of plin ement onrete of 1:5:10 is provided elow ottom se plte. The level of se plteis provided y the spirit level nd the foundtion onrete of M 20 is used. 5.2 Loding setup The portl frme is loded with pulley setup whih is fixed t the right side of the frme with the help of rik pillrs.to fix the dil s, rik pillr is lso onstruted. In this rik pedestl dil is fixed to mesure lterl swy for eh storey. Pge 30

4 6. TEST RESULTS One the loding rrngements ompleted, the portl frmes re tested for lterl lods s well s vertil lods. In this three portl frmes suh s for steel frme, X ring steel frme nd sher wll X ring frme re tested. The frmes re tested for grvity lod nothing ut their self weights. The portl frmes re sujeted to grdul inrements of horizontl lods, i.e 10 kg, 20kg, 30 kg, 40kg, 50kg.The orresponding lterl swy is lulted. 6.1 Model frme without x ring nd sher wll The steel frme is shown in figure 6.1.For lulting lterl storey drift, dil s nmely, A.B nd C is used for ottom storey, middle storey nd top storey.for every 10 Kg lod inrement, swy is omputed in ll dil s for oth loding nd unloding onditions. Tle6.1 shows the test results of steel frme. Due to grdul inrement of lod lterl defletion is lso inresed. It is noted tht top floor swyed more when ompred to middle nd ottom floor. Even fter the unloding residul deformtion is oserved in ll dil s. lods kg Swy in loding(mm) Tle 6.1: Steel frme test results Swy in unloding(mm) Frmes with x- ring Fig.6.1: Steel portl frme Figure 6.2 shows the steel frme strengthen with x frme. The x frme is provided for first nd third y of portl frme. Tle 6.2 shows the test results of x ring portl frme. Even in this x ring frme lso lterl swy is inresed due to rise in lods. But the mgnitude of lterl swy is highly deresed due to provision of x ring. In this se lso plsti or residul deformtion is existed in portl frme. The mximum deformtion of top storey is less thn one mm. Pge 31

5 lods kg Tle 6.2: X-ring portl frme test results Swy in loding(mm) Swy in unloding(mm) Model frme with x ring nd sher wll Fig.6.2: X ring portl frme Figure 6.3 shows the sher wll frme. In this se, the portion of x ring is losed with the sher wll. The sher wll is mde up with ement mortr 1:3. The sher wll is uilt with ement mortr 1:3 nd hiken mesh. Initilly the hiken mesh is pled over the x ring nd ement mortr is pled over this rrngement. Tle 6.3 shows the test results of sher wll frme. In this se, lterl swy of portl frme is very less when ompred with plin frme nd x ring frme. For the first two lodings there is hrdly ny deformtion in oth loding nd unloding ses. Tle 6.3: Sher wll frme test results Swy in loding(mm) Swy in unloding(mm) lods kg Pge 32

6 Fig.6.3: Sher wll portl frme 7. CONCLUSION From the nlytil nd experimentl studies, the lterl swy of portl frmes is less when they re strengthened with lterl lod resisting systems sujeted to lterl lods. The higher deformtion is oserved in steel portl frme where s in x ring nd sher wll portl frmes the lterl defletion is very smll. It is lso to e noted tht the portl frmes re sujeted to less swy in ottom floors in ll three ses. It is due to the rigidity provided y the supports. The lterl story drift rte is more in top storey when ompred with middle nd ottom storeys. The lterl swy is grdully inresed s the lod inresed from 10 kg to 50 kg. It is lso oserved tht the differene of lterl swy vlues etween in dil A nd in dil B is less ut t the sme time differene of lterl swy vlues in dil A nd in dil C is more in ll three ses. Even fter the removl of pplied horizontl lods, the plsti or residul deformtion is still oserved in storeys of portl frmes. It is lso lerly notied from experiment tht one the portl frme is strengthened with dequte systems, it led to redution in swy, of portl frmes. The lterl lod resisting systems tend to oserve the effets used y horizontl lods. The E-ts softwre nlytil progrm re yielded results lesser thn experimentl results. Out of three types of portl frmes sher wll x ring steel portl frme showed very muh less deformtion. The sher wll portl frme showed lesser swy for the grdul lod inrement. It is onluded tht for lterl lods like wind nd erthquke fores, the provision of sher wlls strengthens the struture whih is lerly seen from the redued lterl defletions. So the sher wlls re the est lterl lod resisting systems s they n provide n effiient nd sfe high rise strutures. REFERENCES [1] A.Astneh-Asl, Steel plte sher wlls, U.S Jpn workshop on seismi frture issues in steel strutures, Snfrniso, Fe [2] A. Godinez-Dominguez nd A. Ten-Colung, Behvior ofmoment Resisting Reinfored ConreteConentri Bred Frmes (R-Mrfs) in Seismi Zones, The 14 th World Conferene of Erthquke Engineering,Bejing,2008. [3] KsimArmgnKormz, FutDemir nd Mustf Sivri, Erthquke Assessment of R/C Strutures with Msonry infill wlls, Interntionl Journl of Siene &Tehnology, Vol.2, No.2, pp [4] Krishnrj R. Chvn, H.S.Jdhv, Seismi Response of R C Building with Different Arrngement of Steel Bring System, Interntionl Journl of Engineering Reserh nd Applitions, Vol.4, No.7, pp , July [5] Murthy C.V.R, Erthquke Tips, Deprtment of Civil Engineering, Indin Institute of Tehnology, Knpur,Mrh Pge 33