Abstract:Taking a mid-span continuous bridge as the research subject, the restoring force model of rubber bearing and the dynamical model of nonlinear analysis were established. Also, 100 earthquake wave records were chosen from PEER to conduct a series of nonlinear time-history analyses, and the relative displacement responses of rubber bearings were obtained. Based on the principle of Performance-Based Seismic Design and the theory of seismic vulnerability analysis, a method for determining four different damage indexes of laminated rubber bearing was proposed. According to traditional reliability probability analysis method, a curve between the spectral acceleration and the relative displacement ductility ratios of bearings was fitted, and the fragility curves of different bearings were formed. The results have demonstrated that bearing, especially the bearing on abutment, is more vulnerable than other bridge members under earthquake. Therefore, the seismic performance of bearing will be greatly improved if the thickness of rubber bearings is heightened or the PTFE sliding rubber bearings are adopted for abutment bearing.

Abstract:order to study the effect of compressive stress and shape factors on the vertical stiffness of square laminated rubber bearings, serial compression tests were conducted on four 400×400 mm2 full scale square laminated rubber bearings at stresses of 10 MPa，12.5 MPa and 15 MPa. The relation between the vertical stiffness, shape factors and compressive stress of the four bearings was studied and an experimental expression was obtained. The tests and analysis results have shown that the vertical stiffness of the laminated rubber bearing is compressive stress dependent, the vertical stiffness increases when the compressive stress increases; at constant compressive stress, the increase of the second shape factors will lead to the increase of vertical stiffness; and the compressive stress has more influence on vertical stiffness when the bearing has a large second shape factor value.