Seismic Behaviour of RC Framed Buildings of Different Configurations Resting on Hill Slopes

Structural irregularities are commonly found in constructions and structures. Architectural demands are usually the cause of such irregularities. Most of the constructions in hilly regions are constrained by local topography which results in the adoption of either a step back or step back & set back configuration. Due to this the structure is irregular by virtue of varying column heights leading to torsion and increased shear during seismic ground motion. A type of irregular structure for which some poor performances have been observed during past earthquakes is the vertically setback buildings. A vertical setback is a geometric irregularity in a vertical plane. Setback structures are characterized by abrupt reductions in floor area in the upper stories. Story weight, strength, and stiffness also decrease with height above the foundation, but not necessarily at the same rate. Buildings with vertical setback cause sudden jump in earthquake forces at the level of discontinuity. The general solution of a setback problem is the total seismic separation in plan through separation section, so that portions of the building are free to vibrate independently. When the building is not separated, the lateral-force-resisting elements such as shear walls, bracing systems can be used.In this dissertation work, performance of buildings situated on sloping ground with and without setback has been evaluated. For comparison purpose commonly shaped regular and setback buildings such as stepped type building is selected. Various models are decided with incorporation of shear walls at various locations. Performances of these various combinations are studied and compared. Linear dynamic analysis i.e. response spectrum analysis is carried out on the entire mathematical 3D models using the finite element software ETABS Version 2015.