Shape optimiza tion of compliant mechanisms for seismic isolator model

Abstract

A new concept is presented for seismic isolation system using a compliant mechanism. Optimization approach is utilized for generating a truss structure that has specified equilibrium path, which can be achieved utilizing elastic deformation of a structure and geometrical nonlinearity. The truss structure can be used as a base-isolation system by assigning a path with gradually increasing load with respect to the displacement. Weighted sum of the error of the equilibrium path from the target path is minimized through optimization procedure. The compliant truss mechanism obtained from optimization is designed as the isolator model for the building frame. The effectiveness of our model of isolation system is validated by the result of time history analysis using recorded seismic motions.