EFFECTS OF PLAN ASPECT RATIO ON SEISMIC RESPONSES OF RC BUILDINGS BY TIME HISTORY ANALYSIS

Abstract

Seismic analysis is one of the major developments in the field of civil engineering. Among many seismic analysis methods, nonlinear time history method is undoubtedly the most realistic method as it directly applies the earthquake load on the structure. Selection of ground motion history is important in time history analysis as it should be compatible with the existing building code of the country. Meanwhile, seismic responses of the structure are greatly influenced by its shape, size and geometry. In this study, nonlinear time history analysis has been used to evaluate the seismic responses of three buildings in both X and Y directions with three different plan aspect ratio (length to width ratio) having same area and height. The selected ground motion history is used in the analysis after matching with the design response spectrum of Bangladesh National Building Code (BNBC). Finally, the effects of plan aspect ratio on seismic responses of the buildings are evaluated in terms of displacements and story drifts. Although, all three building models consist of same plan area, story displacements increase in both X and Y directions with the increase of plan aspect ratios. However, maximum story displacements and story drifts are largely increased in Y direction compared to that in X direction as building models become less stiff in Y direction with the increase of aspect ratios.