Reliability-Based Methodology for the Optimal Design of Viscous Dampers

Abstract

Energy dissipation devices are widely utilized to improve the response of structures subjected to dynamic loadings (e.g. earthquakes, winds). In particular, viscous dampers are hydraulic devices widely employed in structural engineering that dissipate the kinetic energy by producing a damping force against the motion. Despite the uncertainty present in the loads (seismic input) and in the structural models, simplified approaches for the design of the damper properties often neglect the response dispersion due to these uncertainties, or treat them in a simplified way by focusing on the mean response only. In this study, a novel reliability-based methodology for the optimal design of nonlinear viscous dampers is proposed. The methodology involves a reliability analysis nested in an outer optimization loop, which seeks the minimization of an optimal function related to the damper cost subjected to the reliability constraint on the structural performance. In particular, subset simulation is used in the inner loop, while the optimization problem is solved via the COBYLA algorithm. The application of the Subset Simulation and of the proposed design approach is illustrated by considering a realistic case study consisting of a three-storey building equipped with nonlinear viscous dampers, for different levels of the damper nonlinearity.