New metallic damper with multiphase behavior for seismic protection of structures

Abstract

This paper proposes a new metallic damper based on the plastic deformation of mild steel. It is intended to function as an energy dissipation device in structures subjected to severe or extreme earthquakes. The damper possesses a gap mechanism that prevents high-cycle fatigue damage under wind loads. Furthermore, subjected to large deformations, the damper presents a reserve of strength and energy dissipation capacity that can be mobilized in the event of extreme ground motions. An extensive experimental investigation was conducted, including static cyclic tests of the damper isolated from the structure, and dynamic shake-table tests of the dampers installed in a reinforced concrete structure. Four phases are distinguished in the response. Based on the results of the tests, a hysteretic model for predicting the force-displacement curve of the damper under arbitrary cyclic loadings is presented. The model accurately captures the increment of stiffness and strength under very large deformations. The ultimate energy dissipation capacity of the damper is found to differ depending on the phase in which it fails, and new equations are proposed for its prediction. It is concluded that the damper has a stable hysteretic response, and that the cyclic behavior, the ultimate energy dissipation capacity and failure are highly predictable with a relatively simple numerical model