Lead Rubber Bearing Large Span Cable-stayed Bridge In The Parameter Optimization

As cable-stayed bridges are increaring popularity,more corcerns are raised about their seismic behavior. Eathquake analysis for long-span cable-stayed bridges has two aims:the first is to ensure enough safety margin against basal earthquake intensity;the second is to provide scientific bases and effective ways for vibration resistance design of bridge.Although several recent investigation have contributed significantly to the earthquake-response analysis,it is still essential that more research be conducted to investigation some aspects of the problems.Lead-Rubber Bearings(LRB) which is used popularly as the seismicity mitigation and energy dissipation devices in bridges have a higher original stiffness and can be easily distorted.It also has little resistance to slow movement such as temperature variation, but distinct resistance to sharp movement of the ground vibration and dissipates energy . It is a significant project that the LRB is applied to pylon and deck connections of the cable-stayed bridge and optimum design of the LRB is performed by using orthogonal design. The following works have been completed in this thesis:1. On the basis of LRB's several mechanical models, the LRB's bilinear delayed circle-curve is simulated by the nonlinear spring element in Ansys.2. The dynamic model of Dongtinghu big bridge in Yueyang is established. The effects of juncture situations between pylon and deck on the dynamic characteristic of the bridge are calculated and studied through Block lanczos3. The seismic response of Dongtinghu big bidge in Yueyang is calculated in three kind of pylon-girder connections. Furthermore, the effects of traveling seismic and geometric nonlinearity on seismic response are discussed.4 . Optimum design of LRB is completed by using orthogonal design and through the nonlinear seismicity analysis method of the structure, the effects of the seismicity mitigation and energy dissipation of the bearings are investigated. The results show that the LRB is an effective method to reduce seismic response.