Nonlinear Dynamic Analysis of Torsionally Coupled Isolated Structures

Abstract

A simple yet accurate approach to evaluate the seismic performance of a torsionally coupled multistory building isolated by nonlinear isolators and subjected to strong ground motions is presented in this paper. In this study, the shear-type torsionally coupled multistory building controlled by the resilient friction base isolation (RFBI) system is presented. The governing equations of motion of the proposed torsionally coupled isolated structure are derived and solved using Newmark’s step-by-step method of integration. MATLAB codes are developed to evaluate the nonlinear responses of the proposed isolated system. Energy dissipation in this structural system occurs due to the presence of frictional force, which is developed through the relative velocity of the base isolator concerning the ground. Detailed numerical results are illustrated to deliver an exact idea regarding the mitigation of structural responses in the presence of the RFBI system during earthquake events. To illustrate the significance of the controlled device, response histories considering the controlled and uncontrolled system as well as other parametric results are plotted. The results obtained from the analysis are feasible and useful for practical design use.