The Seismic Response And Reliability Analysis Of High-speed Railway Bridges Considering Soil-structure Interactions

With the features of safety, convenience and comfort, high-speed railway has achieved fast development in recent years. However, lots of research issues have to be further solved at the same time. In order to improve the safety of the vehicle, bridges are constructed to control the displacement of foundation settlement and isolation foundation movement. Therefore, the research about vibration control and reliability analysis of high-speed railway bridge is of great significance.Based on the project of Beijing-Shanghai High-speed Railway, this paper focuses on the dynamic response of multi-span simply-supported girder bridges under earthquake and gives a systematic research method towards the analysis of this kind of bridge. The research mainly includes the following parts:1.The simulation model of a high-speed railway simply-supported girder bridge with a single span length of 32 m was established based on the finite element method. The connection types are selected as fixed pier bottom and coupled support while the structure is divided by the solid element and the spring-damp element. The dynamic response characteristics of the high-speed railway bridge are analyzed and the figures for some frequency distributions and vibration mode are plotted.2.The seismic response for the simulation model is analyzed by using the response spectrum method. According to the density features of the frequency distribution, the CQC method is selected to conduct a modal merger, thus carrying out the earthquake response. At the same time, seismic response is also analyzed according to the site factors and fortification intensity by using the time history analysis method. After that, the results of the two different approaches are compared under different seismic load and input. As a result, according to this model, the applicability of the response spectrum method in the design stage and the reliability analysis has been testified.3.In order to faithfully simulate the seismic response, this paper established the pile-soil finite element model and used the spring damping system vibration isolation cushion to simulate a vibration isolator. Then, considering the effects of pile-soil interaction and seismic isolation on the earthquake response of the bridge, the response of the high simulation model under the earthquake are revealed. By terms of the study on seismic response of bridge pier height and span length in common condition and the analysis of influence of structural seismic response of the bridge, the paper managed to provide a reference for the selection of structure under different working condition.4.Considering the pile-soil interaction and isolation effect, reliability analysis of the high-speed railway bridge is carried out based on the response surface method. The response surface method greatly improves the efficiency of reliability calculation for such complex engineering problems. Through the calculation of different high pier bridge structures, the reliability of the structures under the standard of the “three levels preparedness” can be evaluated. Furthermore, the reliability analysis provides a reference for the quality control of bridge construction.