An efficient mode-superposition procedure for seismic analysis of base-isolated structures

The paper presents a mode-superposition procedure for the analysis of non-classically damped linear systems. Undamped mode shapes are used to transform the equations of motion to modal equations with the coupling in modal damping expressed as a forcing function in a series. The modal equations are solved analytically using a recursive procedure. The efficiency of the proposed method is illustrated by an example of a base-isolated structure. The responses from the proposed method are compared with those from the complex mode method and with those from the direct integration of equations of motion