Modified Fatigue Model for Hourglass-Shaped Steel Strip Damper Subjected to Cyclic Loadings

Metallic dampers have been used to dissipate large amounts of seismic energy through inelastic deformation in order to minimize damages to the main structural components. However, cumulative inelastic deformation of the metallic dampers results in fatigue cracks, so the life of the device may be reduced significantly. In this paper, an experimental study was carried out to investigate the low-cycle fatigue damage for the proposed hourglass-shaped strip damper (HSD). Four different types of cyclic loadings were applied in this test. The microstructures of the fracture surfaces and the crack distribution patterns were also observed. From the results, it was found that the shape of HSD was well designed for excellent fatigue performance, and the low-cycle fatigue characteristics of the steel strip damper could be well defined by the Manson-Coffin relationship. To consider the mean deformation and the loading sequences, a modified fatigue damage prediction model was proposed that incorporates the effective stiffness. Finally, it may be said that the newly proposed model can predict well the remaining life of the damper damaged by cumulative inelastic deformation.