SEISMIC BEHAVIOUR OF PLAN IRREGULAR BUILDING –AN ANALYTICAL STUDY

Abstract

Synopsis Asymmetric buildings often undergo unfavorable seismic behaviour, which results the irregular concentration of plastic demand in limited or vulnerable portion of the structure and subsequently, invite the early collapse of the structure during seismic vibrations. L-shaped buildings are among those asymmetric structures which are commonly found in the form of school, office, commercial as well as residential buildings. Accordingly, an analytical study is performed to investigate the seismic behaviour of plan irregular buildings. Moreover, to understand the effect of length of projection of the structure on the dynamic characteristics, different projection length lead to different aspect ratios for the same building plan shape have been analyzed here. It is observed that variation in projection length of such buildings have significant effect on the dynamic characteristics. However, the seismic response of few L-shaped buildings are analyzed using nonlinear static method and results have been shown in terms of capacity curve, performance point, interstorey drift, column shear, and plastic hinge formation pattern. Seismic demands of asymmetric systems are found to be potentially high due to its asymmetric distribution of mass, stiffness and strength, which is one of the major sources of damage, as it causes torsional floor rotation.