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Bp33409412

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Bp33409412

  1. 1. A.K.Chikyal, Karim Pathan, Ansari Altaf ul Hassan, Mohammed Nabeel / InternationalJournal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.409-412409 | P a g eSeismic Response of Buildings with Column ReinforcementLapped Just Above Floor LevelA.K.Chikyal1, Karim Pathan2, Ansari Altaf ul Hassan3, MohammedNabeel41.Department of Civil Engineering, SYCET , Aurangabad-05, (M/S) India,2.Consulting Structural Engineer, Aurangabad -05, (M/S) India,3. Student, SYCET , Aurangabad-05, (M/S) India,4. Student, SYCET , Aurangabad-05, (M/S) India,ABSTRACTThe response of beam-column jointshave long been recognized as a significant factorthat affects the overall behavior of reinforcedconcrete (RC) framed structures subjected tolarge lateral loads. The reversal of forces inbeam-column joints during earthquakes maycause distress and often failure, when notdesigned and detailed properly. The principleobjective of this work is to analyze several“G+10” storey buildings having reinforcementjoint (lap) just above the floors. An attempt ismade to study the behavior of such structureswith the conventional modeling. As a commonpractice, the structures are constructed bylapping the 100% of the reinforcement just abovethe floor instead of lapping it at mid height. It isassumed that column joints near the base where100% lapping is being done, behaves as a hingewhich will transfer only vertical/horizontal loadswithout moments. The response of such structureis compared with those where the detailing isdone properly by maintaining the reinforcementjoint at mid height and not more than 50%lapping is done.Key words: column joints, joints in RCCstructures.I. INTRODUCTIONColumn joints in a reinforced concretemoment resisting frame are critical parts for transferof loads effectively between the connectingelements (i.e. beams and columns) in the structure.In the analysis of reinforced concrete momentresisting frames the joints are generally assumed asrigid. In countries like India, the joint design isusually given lesser attention being restricted toprovision of sufficient anchorage for beamlongitudinal reinforcement. This may be acceptablewhen the frame is not subjected to earthquake loads.There have been many catastrophic failures reportedin the past earthquakes, in particular with Turkeyand Taiwan earthquakes occurred in 1999, and inbhuj Gujrat earthquake which have been attributedto column joints. Unsafe design and detailing withinthe joint region make unsafe and unwarned theentire structure, even if other structural membersconfirm to the design requirements. The paper isaimed by comparing the forces occurred in buildingswith poor column joints with hinges (as detailed andconstructed without seismic considerations) andwith detailed as per recommendations that makingdesigners aware of the theoretical background on thedesign of column joints highlighting importantparameters affecting seismic behavior of joints.II. PERFORMANCE ANALYSIS:ANALYSIS OF G+10 BUILDING MODELSSeveral models of (G+10) buildings withstorey height 3.15m, 3.6m and 4.2m are analysed.Each of these floor height are modeled for differentbays in each direction ( like 4 x 4 bays , 4x5 baysand 5 x 5 bays ) with different bay widths. Thebehavior of Exterior, edge and interior (C1, C2, andC3) are studied and the response is compared. Thebehavior of peripheral, outer bay and inner baybeams (B1, B2 and B3) is also studied. Anunsymmetrical building is chosen for case study forthe purpose of authentication of the symmetricalmodels studied above.The responses of all above models arestudied by applying the Earthquake force equivalentto 0.3g acceleration.III. COMPARISION AND CONCLUSIONSAll total nine models are studied along withthe case study of unsymmetrical building. EveryModel is prepared as a conventional and as modifiedhinge joint at base due to critical location of lap. Theresponse is compared in terms of Axial Force,Bending Moment and Shear force in columns aswell Bending Moment and shear force in the beams.
  2. 2. A.K.Chikyal, Karim Pathan, Ansari Altaf ul Hassan, Mohammed Nabeel / InternationalJournal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.409-412410 | P a g eTable 1: Comparison of Axial Force in Columns (Model 1, Floor height 3.15m, 4 x 4 bays)GROUPA.F. (Modified Model)kNAF (Conventional Model)kN%DifferenceC1 2.4E3 2.46E3 2.43C2 3.69E3 3.7E3 0.27C3 4.88E3 4.83E3 1.02The trend of axial force is same and not significant in all bays like 4x4, 4x5 and 5x5 hence not shown. The otherresponse is graphically presented here after.Table 2: Comparison of Shear Force in Columns (Model 1, Floor height 3.15m, 4 x 4 bays)GROUPS.F. (Modified Model)kNS.F (Conventional Model)kN%DifferenceC1 56.620 45.869 18.98C2 53.036 53.842 1.51C3 53.925 55.200 2.36The response for other models is graphically presented here afterTable 3: Comparison of Bending “My” in Columns ( Model 1, Floor height 3.15m , 4 x 4 bays )GROUPMy (Modified Model)kNmMy (Conventional Model)kNm%DifferenceC1 133.927 71.396 46.69C2 152.069 81.879 46.15C3 153.097 83.070 45.74The response for other models is graphically presented here afterTable 4: Comparison of Bending “Mz” in Columns (Model 1, Floor height 3.15m, 4 x 4 bays)GROUPMz (Modified Model)kNmMz (Conventional Model)kNm% DifferenceC1 134.761 127.491 5.70C2 167.062 129.634 22.4C3 169.864 131.940 22.32The response for other models is graphically presented here after
  3. 3. A.K.Chikyal, Karim Pathan, Ansari Altaf ul Hassan, Mohammed Nabeel / InternationalJournal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.409-412411 | P a g eChart 1: Variation in A.F., S.F., and Bending moments for column group “C1”Chart 2: Variation in A.F., S.F., and Bending moments for column group “C2”Chart 3: Variation in A.F., S.F., and Bending moments for column group “C3”IV. CONCLUSION:The output of the study is really anattraction to the structural engineer. Though, thereis no significant change in Axial force in columns(as it should be), the variation in Shear force andBending Moment is of very much concern. Thevariation in shear force upto the extent of 40%where as the variation in My moment is havingmaximum value of 65% which really cannot be atolerable. Hence, it is recommended to analyse theRCC framed structure by considering the hinges atthe base of columns at every floor for the purposeof safety at least if someone can’t rigorously go forthe joint design.
  4. 4. A.K.Chikyal, Karim Pathan, Ansari Altaf ul Hassan, Mohammed Nabeel / InternationalJournal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.409-412412 | P a g eREFRENCES:1. P. Rajaram, A. Murugesan and G.S.Thirugnanam, “Experimental Study ofInterier RC Beam Column JointsSubjected to Cyclic Loading,”International Journal of AppliedEngineering and Research, Dindigul, Vol1, 2010, 49-58.2. K. Ravichandran, C. Antony Jayasehar“Seismic Retrofitting of Exterior BeamColumn Joints using ferrocement”,International Journal of Engineering andApplied Sciences, Vol.4, Issue 2 ( 2012),35-58.3. Ravi, S Robert, Arulraj and G Prinec,“Experimental Investigation on Behaviorof RCC Beam Column Joints Retrofittedwith GFRP-CFRP Hybrid wrappingsubjected to load Reversal”, Internationaljournal of Mechanics and Solids, Vol.5,Issue 1, 2010.4. Gustavo J Parra-montecinos, Sean W.Peterfreund and Shih-ho Chao, “HighlyDamage Tolerant Beam Column Jointsthrough use of high performance fiberreinforced cement composites”, ACIStructural journal, Vol. 102, No. 3,2005,487-495.5. N.Vijayalakshmi, M.Kalaivani,A.Murugesan and G.S.Thirugnanam,“Experimental Investigation of RC­BeamColumn Joint Strengthening by FPPWrapping”, International Journal of Civiland Structural, Vol.1, No.1, 2010, 35-49.6. Bindhu K.R, Sreekumar K.J “SeismicResistance of Exterior Beam Column Jointwith Diagonal Collar Stirrups” submittedto International Journal of Civil andStructural Engineering”, Volume 2, No 1,2011.

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