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.
Highlights
The 1994 Northridge (California) and 1995 Kobe (Japan) earthquakes highlighted that a conventional seismic design—where the beams and columns of the main structure are designed to dissipate energy through plastic deformations under a severe ground motion—results in significant structural and nonstructural damage and the interruption of a building’s use after the event
The latter is formed by special structural elements called energy dissipation devices (EDDs), or dampers, plus the auxiliary elements that connect the EDDs with the main structure
This paper presents a simple numerical model that can accurately reproduce the increment of restoring force at large displacements, as well as the amount of dissipated energy, and predict the force displacement hysteretic curves of the metallic damper under arbitrarily applied cyclic loading until failure
Summary
The 1994 Northridge (California) and 1995 Kobe (Japan) earthquakes highlighted that a conventional seismic design—where the beams and columns of the main structure are designed to dissipate energy through plastic deformations under a severe ground motion—results in significant structural and nonstructural damage and the interruption of a building’s use after the event. Structures with energy dissipation systems have proven to be a very effective solution to attain the objectives of PBD. They consist of a main structure that supports the gravity loads and an energy dissipation system working in parallel. The damage concentrates in the EDDS, which is purposely designed to be inspected, replaced or repaired after a severe (commonly called “design earthquake”) or an extreme (“maximum credible earthquake”) ground motion. This allows for the continuous use of a building without interruption, enhancing resilience. The mechanism for energy dissipation resides in plastic bending/shearing deformations of the steel strips
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