Seismic Response Analysis For Railway Bridge Crossing The Active Fault

Because of the special characteristics of the fault ground motion, many researchers in the field of earthquake and engineering regarding it as a research focus in recent years. Due to its special pulse function, the seismic risk of the buildings and structures in the fault area is much higher than that in other regions. Study on fault ground motion response of the structure under the action and the damage mechanism becomes one of the most need to solve the problem. Although domestic and foreign seismic codes are in the Ordinance gives the structure should be as far as possible to avoid building in seismic active fault area, but when structures inevitably cross the active fault, the design must consider the effect of fault on seismic. This paper use the Kuokesa bridge as the engineering background, input artificial synthetic seismic wave analysis of the bridge in the fault pulse type ground vibration under the action of seismic response. The main research contents of this paper are as follows:Referring to the research results at home and abroad, this paper introduces the definition and classification of the fault pulse-type ground motion, and analyzes the effect of the direction and the static impact on the structure.In view of the special pulse function of fault ground motion, the low frequency component and high frequency component are simulating respectively, and the simulation time history of the fault effect can be generated.In the engineering background of the bridge as example, input model by using multi-point displacement excitation and acceleration of ground motion, discusses the applicability of the calculation of the earthquake response of the structure of two kinds of input methods, and displacement input method can be used to simulate the residual deformation and internal forces caused by faults move, in line with the actual earthquake damage characteristics.By means of theoretical analysis and finite element calculation, the time history response of the bridge under the action of pulse ground motion and impulse ground motion in the direction effect fault is analyzed. The results show that the pulse effect of the fault ground motion can increase the damage of the bridge pier, which may cause the upper structure to jump and the beam is damaged.Applicability of lead rubber bearing(LRB) in bridges crossing fault is discussed, pointed out that this type of the bridge in the fault pulse type ground motion, reducing bearings than ordinary rubber bearing can play a greater role, but to achieve the best damping effect still need optimization to reduce the parameters of the isolation bearings.