Seismic performance of the combined viscous-steel damping system suffering from oil leakage

Abstract

The combined viscous-steel damping system is a passive energy dissipation device consisting of a fluid viscous damper and a steel yielding damper in series. However, many viscous dampers installed in structures have been suffering from severe oil leakage. This study aims to assess the influence of the leaked viscous damper on the seismic performance of the combined system. Cyclic tests were conducted on the viscous damper with different leakage levels to obtain its degraded hysteretic performance. The modeling method of the leaked viscous damper was proposed according to the experimental result. The locking behavior and seismic mitigation effectiveness of the combined system suffering from oil leakage were investigated based on a single-degree-of-freedom system. The result reveals that (i) The leaked viscous damper cannot generate damping force at the beginning of the reverse movement of its piston, which is reflected in the hysteretic curves as a “gap” phenomenon. (ii) The proposed modeling method can accurately simulate the damping characteristics of the leaked viscous damper. (iii) In spite of the leakage severity, the combined system possesses reliable locking behavior and decent vibration mitigation effectiveness under earthquakes. (iv) The combined system is superior to the viscous damper in mitigating seismic-induced displacement when suffering from oil leakage.