Hysteretic Restoring Force Characteristics of High Damping Rubber Bearings Under High Compressive Stress

Author(s):  
Yasuhiro Kasahara ◽  
Shigenobu Suzuki ◽  
Takashi Kikuchi

Hysteretic restoring force characteristics — shear stiffness, equivalent damping ratio, and ultimate properties — of seismic isolation bearings are significantly affected by compressive stress. In this study, dependence of shear properties of high-damping rubber bearings (HDR) on the compressive stress σ and secondary shape factor S2 was studied by dynamic loading test with scaled-model and static loading test with full-scale isolators. The results highlighted the high compressive stress dependency on restoring force characteristics of HDR with the isolator of relatively small S2. It is concluded that large S2 is desired when isolators are designed for high compressive stress. The applicability of HDR under high compressive stress was experimentally verified.

Seismic isolation is one of the most efficient techniques to protect structures against earthquakes. Rubber bearings are suitable for low-rise and medium-rise buildings due to its durability and easy fabrication. This paper presents the hori-zontal response of a six-storey base-isolated building using high damping rubber bearings (HDRB) under two ground motions of earthquakes as types I and II in JRA (2002) by finite element analysis. In this analysis, these bearings are mod-elled by the bilinear hysteretic model which is indicated in JRA and AASHTO. Comparison of horizontal response including base shear force and roof level acceleration between the two cases: base-isolated building and fixed-base building is carried out to evaluate the effectiveness of the use of HDRB on the protection of buildings from earthquakes. The numerical results show that the peak value of roof floor acceleration of the fixed-base building is two times higher than that of the base-isolated building, and the floor accelerations depend on the peak values of ground acceleration. In addition, the step-by-step design procedure for deter-mining the size of HDRBs used for buildings is also presented in this paper.


Sign in / Sign up

Export Citation Format

Share Document