Influence of nonlinear viscous dampers on the probabilistic seismic response of linear structure

The paper aims at evaluating the influence of damper properties on the probabilistic seismic response of structural systems equipped with nonlinear viscous dampers. For this purpose, a linear single-degree-of-freedom system with an added linear or nonlinear viscous damper is considered, and the response statistics due to a set of natural records describing the ground motion uncertainty is analyzed in detail. A dimensional analysis of the seismic problem is applied first to identify the minimum set of characteristic parameters describing the system and controlling the seismic response. An extensive parametric study is then carried out to estimate the influence of the damper properties on the statistics of the main response quantities of interest (i.e., maximum displacements, accelerations and forces), for a wide range of values of the characteristic parameters. Finally, a set of case studies is investigated in order to show some interesting issues concerning the influence of the damper nonlinear behaviour on the evaluation of the system reliability and to highlight some limitations of current approaches neglecting the probabilistic properties of the response