Seismic Response Analysis Of Multi-span Continuous Isolated Bridge Under Traveling Wave Excitation

Earthquake is a complex spatial motion, it should be considered the spatialvariation in ground motions for seismic response analysis of structures with large size.For the multi-span continuous isolation bridges, as the particularity of bring isolationdevice by itself, researches on travelling wave effect for the multi-span continuousisolation bridges are relatively few. Based on this background, this paper choose a sixspan continuous isolation bridge as the main research object, to research traveling waveeffect. Main work has been done and the corresponding results had been made in thisthesis:1. To research the mechanism of isolated bridge with lead rubber bearings underthe action of horizontal harmonic wave, to simulate the main frequency of groundmotion by input sine waves at different frequencies and study structure response withthe predominant period of ground micro-tremor change, there are two situations:uniform and multi-support excitations. The influence of traveling wave effect on eachpart of isolation bridge t is different, it would be bad for substructures and isolationlayer, especially isolation layer when excitation frequency is less than natural vibrationperiod of structural, but for the upper structure of bridge is favorable at any time.2. Study the seismic response of lead isolated bridge under traveling waveexcitation with three seismic waves, the results show: The earthquake response ofbridge exists obvious differences because of the different characteristic of seismicspectrum and different wave velocity. In a general way, the more proportion of longperiod spectrum and the slower of wave velocity, the adverse effects for isolated bridgewould be.3. Input the seismic waves in single、double and three propagation directions forisolated bridge, the results show: It has little impact on travelling wave effect bydifferent dimension of seismic waves, rules under multidimensional travelling waveexcitation can refer to the unidirectional excitation. And traveling wave effect has littleimpact on seismic response of transverse to the bridge, which can be minimal.4. Verify the effectiveness of the isolation technique and observe the impact onisolated bridges under travelling wave excitation through shaking table test. To verifythe reliability of shaking table test and the main conclusion with the aid of finite element program.