A unified analysis model for energy dissipation devices used in seismic structures

To date, various types of energy dissipation devices (EDDs) have been invented and applied to structural systems for mitigating their seismic responses. An elastic structure with EDDs can be treated as a nonlinear dynamic system with hysteretic property. Due to the diversity of the hysteretic properties of various EDDs, it is difficult to obtain a generic analysis method that can be applied to structures with different EDDs. In this study, a unified analysis model containing an internal variable is proposed for simulating the hysteretic behavior of various types of EDDs. By assigning different physical meanings to the internal variable, the model is able to simulate three types of widely used EDDs, namely, yielding, viscoelastic, and friction dampers. The unified model is also able to simulate nonlinear viscous dampers whose velocity terms have an exponential coefficient not equal to 1.0. Furthermore, based on this model, this article also developes a numerical analysis method derived from the discrete-time solution of a state-space equation. Without requiring iteration at each computational time step, the numerical method is able to accurately simulate the hysteretic properties of the three kinds of EDDs. The accuracy and efficiency of the proposed analysis method is investigated by using the analytical solution of a nonlinear system governed by Duffing's equation, and also by using a seismic structure equipped with multiple EDDs.