Base Isolated connected buildings subjected to seismic and blast induced vibrations

Abstract

In the present study, the passive control of closely spaced base isolated and fixed base buildings are investigated under the effects of earthquakes and blast induced vibrations. The study advocates the installation of viscous dampers (FVDs) to protect the closely spaced base isolated buildings adjacent to fixed base buildings against seismic and blast excitations. The performance of a five storied base isolated building is reviewed such that time period of isolated building (Tb) is 2.5 sec with isolation damping is assumed as 5% and connected to an adjacent fixed base building such that it has three storey and structural time period 0.5 sec. The effectiveness of damper connected base isolated and fixed buildings is also analyzed for isolation period 2 sec and 3 sec respectively. Nonlinear direct integration method has been adopted to evaluate the performance of fixed base and base isolated structures for connected and unconnected state. The equations of motions are formulated and solved using MATLAB code by Newmark’s average acceleration method. The lead rubber isolators are designed and idealized as Bouc Wen model. A parametric study is also conducted to determine the optimum damper properties for the fixed base buildings and base isolated connected buildings with viscous dampers. Results exhibit the efficiency of viscous dampers in reducing the structural responses of the base isolated buildings. It has been observed that in case of fixed base buildings, the peak responses show an effective reduction in responses. The effectiveness of the passive control technique using viscous dampers in mitigating the bearing displacements of base isolated structures subjected to seismic and blast induced vibrations is also reported.