Research on Hysteresis Model of High Damping Rubber Bearings Considering Mechanical Properties Based on Dynamic Loading Test

High damping rubber bearings (HDR) are made by combining natural rubber with carbon fillers. Because of its simple structure can be easily applied to seismic isolation design and is easy to manage. Also, high damping rubber bearings are seismic isolators with excellent damping ability against earthquakes. High damping rubber bearings have high horizontal flexibility against earthquake motion and can dampen seismic energy, but the mechanical dependence resulting from material properties cannot be ignored. This research aims to experimentally reveal the dependence and nonlinearity of high damping rubber based on dynamic loading tests and to propose an advanced accurate hysteresis model. First, a dynamic loading test was performed using a scaled-down high damping rubber specimen, and mechanical properties such as equivalent stiffness, equivalent damping constant, and strain energy were evaluated. Subsequently, based on the mechanical evaluation, a hysteresis curve was modeled considering the characteristics of high damping rubber. In this research, a hysteresis model considering these characteristics was proposed by focusing on the rate dependence due to the Mullins effect and the hardening phenomenon occurring in the region of large shear deformation, such as a large earthquake. Finally, the actual behavior of high damping rubber and the feasibility of the modeling procedure were evaluated by comparing the results of the dynamic loading test using seismic waves assuming real earthquakes and dynamic analysis. As a result, it was possible to propose a hysteresis model that can represent the nonlinear characteristics of high damping rubber.