SEISMIC EVALUATION OF FLAT SLAB BUILDING WITH SHEAR-WALL-CORE

Abstract

Use of flat slab is promoted highly these days due to its ease in construction, economy, faster construction and cost cutting by using slip forms in construction. Flat slab construction gives lesser floor to floor height for the same head-room. Generally flat slab-column system is designed in lower seismic zone areas for resisting gravity loading. Its performance reduces drastically as this system in introduced to lateral loadings of higher seismic zones. Thus to resist this lateral loading this system is provided with lateral load resisting elements such as shear-walls or shear—wall—cores. In the current study, behavior of flat slab-column system, designed safe for resisting gravity loading, studied for lateral loading of Zone IV and Zone V as defined in IS: 1893-2002. Along with this how its behavior varies and improves with the introduction of shear=wall-core is studied using static non-linear analysis i.e. Push over analysis and results are presented for the same. The 3-D model of flat slab structure is created using SAP-2000. The buildings with 8, 12 and 16 storey with and without Shear-Wall-Core are taken for study. For modeling of flat slab, explicit transverse torsional member method is used. For modeling of Shear-wall-Core, Wide columns with rigid links method are used. Provisions of FEMA 356, ATC -40 and ACI 318-05 are used to define user defined hinge properties. On the basis of presented results it can be concluded that flat slab structure doesn't behave like conventional beam column structure. With the introduction of shear core, the behavior of flat slab structure improves drastically. Also here the behavior of structure with 1% shear wall is comparedwith 1% shear-wall-core. And it has been concluded that even after having same percent of wall areas, shear core structure behaves better than flat slab, structure with shear-walls.