Experimental study on the bidirectional inelastic deformation capacity of U‐shaped steel dampers for seismic isolated buildings

Summary Hysteretic dampers are used to dissipate earthquake-induced energy in base-isolated structures by acquiring inelastic deformations, rendering their hysteretic behavior of vital importance. The present paper focuses on investigating the behavior of U-shaped steel dampers under bidirectional loading; this is significantly different from their corresponding uniaxial behavior. Two main sets of loading tests on full-scale specimens are conducted in this regard: (i) quasi-static tests with simple histories and (ii) dynamic tests with realistic loading histories. Based on the results obtained in the quasi-static tests, an interaction curve that accounts for the reduction of the cyclic deformation capacity is proposed. However, the fidelity of this relation must be assessed under loading conditions similar to those of a seismically isolated structure subjected to an earthquake, which represents the goal of the second set of tests. The results of the dynamic tests validate the proposed interaction curve for estimating the deformation capacity of U-shaped steel dampers under bidirectional loading. Copyright © 2015 John Wiley & Sons, Ltd.