Comparative Study on Evaluating and Improving Seismic Load Resistance of Multistorey Buildings with Floating Columns

Abstract

In the present scenario, due to less availability of space and more population, in multi-storey buildings (both residential and commercial) an open space is reserved for parking, assembly hall or for auditorium purposes at any level or storey by using floating columns. This floating column is a vertical member which rest on a transfer beam but does not transfer the load directly to the foundation. The floating column acts as a point load on the transfer beam and this beam transfers the load to columns found below it. However, deviation or discontinuity in this load transfer path results in poor seismic resistance of the building, which raised interest on this research. This research study is attempted to compare the parameters which includes the effect of floating column provision on seismic resistance of buildings, assessing optimum position of floating column that can better resist seismic force, evaluating effect of critical beam and column dimension increment on building with floating columns, evaluating percentage effect of lift shear wall provision on seismic resistance of building with floating columns. It was done on symmetrical 6-storey building, by comparing three critical parameters; storey displacement; storey drift and storey shear using ETABS 2016.00 as per ES EN 1998-1:2015. As per comparison made, provision of floating column at ground floor edge corner increased maximum lateral displacement of the building without floating column by 31.4% due to structural irregularity occurred in discontinuity of load transfer path, while changing position of floating column from ground floor edge corner to fourth floor parallel position led to decrement of lateral displacement by 4.4%. Increment of critical beam and column dimension reduced lateral displacement of optimized position floating column building by 0.69% and 8.21% respectively. Providing Center lift shear wall on optimized position floating column building reduced lateral displacement by 22.17%, using combination of lift shear wall and critical member dimension increment reduced lateral displacement of optimized position floating column building by 28.03%. Generally, the result show that provision of floating column reduce seismic resistance of buildings which can be improved by moving floating column from outer edge to inner edge, from lower to upper floor, increasing column supporting transfer beam and using lift shear wall for vertical transportation