Research On The Key Parameter And Optimization Of Bridge’s Viscous Damper

Our country is an earthquake-prone country, and a large area of land is in the zone with frequent earthquakes, therefore, anti-seismic engineering is a very important issue. Seismic mitigation and isolation technology is widely used in the anti-seismic engineering of bridge. As viscous damper has good seismic behavior and applicability, it can be a better choice for controlling seismic response of long-span bridges.The paper introduces the classification, characteristics, energy principle and restoring force model of viscous damper, and discusses the anti-seismic theoretical analysis of bridge structures with viscous damper. According to the simplified nonlinear Maxwell model, damping coefficient C is chosen as the key parameter to be studied. Traditional parametric sensitivity analysis method can obtain the optimal viscous damper parameter combination of the bridge effectively; however, many problems come along, such as large amount of computing and data processing, time-consuming, inefficiency and other issues. Therefore, the paper uses random vibration theory to deduce the optimal damping ratio of single-freedom vibration system and theoretical formula of the corresponding optimal damping coefficient. Using the energy equivalent theory, deduce an optimal damping coefficient expression of nonlinear viscous dampers.Taking a continuous beam bridge as an engineering example, establish finite element model with the finite element analysis software of MIDAS/CIVIL 2013, and analyze its dynamic characteristics to get the optimized damping coefficient. Using the nonlinear time history analysis, verify that the optimization method of damper parameters based on random vibration theory is correct.The paper has discussed optimization design of the viscous damper from the structural design, viscous media and sealing aspects and has made some useful suggestions.