Seismic Performance And Analysis Method Of Polyurethane-lead Core Damper

With the rapid development of China’s high-speed railway construction,it is necessary to conduct seismic design for high-speed railway bridges.Compared with traditional seismic design methods,seismic isolation technology is more widely used in seismic design of high-speed railway bridges.Based on the design idea of "separation of support function",a combination of polymer material polyurethane and metal lead is proposed to form a bridge seismic mitigation device-polyurethane-lead core damper.In this paper,the mechanical properties and energy dissipation capacity of polyurethanelead core dampers are studied through stiffness and energy dissipation tests.The research content is as follows:1.The structural form,working mechanism and installation method of polyurethanelead core damper are expounded,the calculation model and flow chart of design parameters are given,and the calculation formulas of initial stiffness and critical elastic displacement are derived.The material properties of the two groups of polyurethanes of JA and JB were tested to obtain the elastic modulus and Poisson’s ratio of the material,and the performance of JB was better than that of JA.JB was determined as the lead core wrap.2.Carry out stiffness and energy dissipation test research on four groups of full-scale polyurethane-lead core damper specimens,understand the failure process and failure form of the specimen,obtain the hysteresis curve of the specimen,and establish the polyurethane-lead damper The restoring force model and evaluate its mechanical properties such as strength,stiffness,energy dissipation capacity,etc.;the hysteresis process of the polyurethane-lead damper is compared with the numerical simulation test results to verify the accuracy of the numerical simulation results.3.Six equivalent linearization calculation methods for calculating the equivalent stiffness and equivalent damping ratio are described,and the calculation methods for the equivalent stiffness and equivalent damping ratio of the polyurethane-lead damper are determined.The damping ratio and damping coefficient of the polyurethane-lead damper beam bridge system are analyzed.The steps and flow chart of the simplified calculation method for single-degree-of-freedom response spectrum seismic isolation design are given,and the simplified method is used to calculate a simple-supported beam bridge engineering example.The calculated shock absorption rate is more than 70%,indicating that the lead core damper has good seismic mitigation effect.4.The non-linear time-history analysis of the longitudinal direction of the simply supported beam bridge with polyurethane-lead core damper is used to calculate the seismic response,and compared with the simplified calculation method of the simple supported beam bridge seismic isolation.It is concluded that the comparison results of the two calculation methods are in good agreement,and the accuracy of the method is verified with each other.The study analyzed the influence of yield strength,post-bending stiffness ratio,bridge pier height,and friction of movable support on the seismic isolation effect.