Research On The Seismic Performance Of Isolated Bridges With Friction Pendulum Bearing

Friction pendulum bearing (FPB) is an efficient isolation device, and it is widely used in the new bridges or bridge reinforcement project. But the national standard of FPB hasn’t been formulated at present. Moreover, FPB is commonly used in isolation buildings rather than isolation bridges in China, and now the theory research and optimization design focus on isolation bridges used FPB are less. In this dissertation, the optimization analysis of the equivalent linear mechanical model of FPB is completed firstly. Subsequently, the optimization design of FPB used in the isolation bridges is studied based on the dynamic response results and energy methods respectively. The mechanical properties of FPB in the horizontal direction are studied through experiment research, and the test results can provide the basis for the theoretical analysis above. The main contributions of this dissertation are listed below.(1) The nonlinear dynamic model of continuous beam bridge with FPB is established used SAP2000, and the influences of seismic waves (acceleration amplitude, spectrum characteristics) and parameters (slide radius, friction coefficient) of FPB on the sliding displacement are studied used finite element simulation, then the empirical formula of sliding displacement is established based on the analysis results. The design displacement of FPB in different seismic fortification areas are formulated, then the dynamic responses of isolation bridges are studied by establishing dynamic equilibrium equations. The research object is high-speed railway bridges. Then the seismic responses of isolation bridges are studied used theoretical methods and finite element simulation respectively in different earthquake excitations (El Centro wave, Taft wave, Northridge wave and others), and the influence of sliding displacements on the theoretical calculation precision is studied.(2) The finite element model of FPB is established used ABAQUS, and the influences of concrete pier on the stress and deformation distribution of FPB are studied. Then the structural strength of FPB in different sliding displacements is studied, and the method is put forward to improve the safety coefficient of structure strength. The dynamic responses of isolation bridges in multi-dimensional seismic waves with different bearings are studied. In order to control the dynamic response amplitudes of the isolation bridges, the optimization design of radius and friction coefficient of FPB is studied.(3) The energy balance equations of isolation bridges with FPB are established, and the time history curves of energy responses are solved used MATLAB. In order to study the calculation accuracy of theoretical method, the energy response curves calculated by theoretical analysis are compared with that of finite element simulation. The finite element models of isolation and non-isolation bridges are established, and the isolation performance of FPB is studied in different working conditions. The influence of seismic wave and parameters of FPB on the seismic input energy is studied. In order to minimize the seismic response energy of isolation bridges and ensure the FPB have higher energy consuming ratio, the optimal values of slide radius and friction coefficient of FPB are studied in different seismic waves.(4) The mechanical properties of friction pendulum bearing in the horizontal direction are studied by experiment research. The mechanical parameters and hysteretic curve of FPB in different sliding displacements are studied. The influence of sliding displacement on the mechanical properties of FPB is studied based on hysteretic curves, then the mechanical parameters of FPB calculated by theoretical analysis are compared with experiment results, which can provide the experimental basis for the theoretical analysis.