Study On Vulnerability And Dynamic Performance Of High-speed Railway Bridge After Earthquakes Considering Spatial Variability

With the rapid development of economy and society, high-speed railway is playing a more significant role than ever in solving traffic problems between big cities, and the proportion of bridges in high-speed railways is also increasing. In high-speed railways, elevated bridges usually extend for a few kilometers or even hundreds of kilometers, as a result of which the supports of the bridge are usually subjected to different ground motions. Therefore, the influence of the seismic spatial variability plays an important role in bridge analysis. However, it has not been considered sufficiently in research of bridge vulnerability and dynamic characteristics after earthquakes.In this paper, the factors leading to spatial variability of earthquake ground motions are analyzed, and the unconditional and conditional simulation algorithms are introduced to obtain the non-stationary acceleration time histories of multiple supports by programming with MATLAB. A visual interface is also designed. Besides, a finite element model of a high-speed railway bridge is established in ANSYS and the influence of bridge seismic vulnerability is analyzed. In the end, the operation performance of train after an earthquake is studied. The research mainly covers the following contents:(1) The background and research status of spatial variability of earthquake ground motions are introduced and so is the fundamental theory of MATLAB GUI.(2) Based on the previous research about ground motion simulation, the spatial variability is taken into consideration by using unconditional and conditional simulation algorithms respectively, and analyzed under conditions of uniform excitation as well as multiple-support excitation, providing satisfactory theoretical basis for reasonable ground motion simulation. Meanwhile, the MATLAB GUI is used to design a visual interface, which is convenient for users to operate.(3) The research status of bridge vulnerability is introduced and a finite element model of a practical high-speed railway bridge is established, the seismic vulnerability of which is analyzed with displacement ductility ratio as damage index.(4) The dynamic performance of a real damaged bridge after earthquake is analyzed under conditions of different velocities as well as different damage degrees.