An efficient computational strategy for nonlinear time history analysis of seismically base-isolated structures

Nonlinear time history analysis represents the most appropriate structural analysis procedure to accurately analyze seismically base-isolated structures since their dynamic response is typically governed by a system of coupled nonlinear ordinary differential equations of the second order in time. The selection of a suitable phenomenological model, required to accurately describe the hysteretic behavior of each seismic isolation bearing, as well as of a time integration method, required to numerically integrate the nonlinear equilibrium equations, plays a crucial role in performing such analyses. Indeed, both the phenomenological model and time integration method directly affect the accuracy of the results and the computational burden of the analyses. This paper proposes an efficient computational strategy obtained by combining a novel phenomenological model and an explicit structure-dependent time integration method. Numerical accuracy and computational efficiency of the proposed solution strategy are assessed by performing several nonlinear dynamic analyses on a seismically base-isolated structure and comparing the results with those obtained by employing a widely used conventional procedure.