Effects of to Near-Fault Directivity Pulse -like Ground Motion on Elastic-Plastic Seismic Response of High-speed Railway Bridge
Chen Ling-kun 1,2, Zhang Nan2, Hu Chao1, Xu Qing-yuan3
1. College of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, China; 2 School of Civil Engineering, Beijing Jiaotong University, Beijing, 100044, China; 3. School of Civil Engineering, Central South University, Changsha, 410075, China
Abstract：Based on the PEER-NAG Strong Ground Motion Database, the finite element model of the multi-span simply supported bridge is set up by means of ANSYS software, ANSYS-APDL language and moment-curvature program in the paper, the natural vibration properties of structure is analyzed, the elastic-plastic seismic responses of bridge subjected to the near/far-fault ground motions are calculated. The calculation results show that, for the hysteretic characteristics of the near-fault directivity pulse-like earthquake, the more just expression should be the moment-rotation relationship of pier bottom is characterized by the central strengthened hysteretic cycles at some point of the loading time-history curve corresponding to the time of the pulse, it require the bridge piers to dissipate considerable input energy in a single or relatively few plastic cycles, it is mean that the ductility capacity of the piers should be improved; the displacement of girder and pier top, moment of the pier bottom increase under near fault ground motion compared with far-fault ground motion; the energy dissipation on the bridge system subjected to a far-fault motion tends to gradually increase over a longer duration, causing an incremental build-up of input energy; as the greater vertical earthquake action of the near-fault earthquake, there are the large vertical deflection in the mid-span of girder; GB 50111-2006 Code for seismic design of railway engineering specify that the vertical earthquake force can be taken as 67% of the lateral earthquake, it's advisable that the reasonable value of vertical earthquake acceleration should be utilized to carried simulation calculation.
2013, Vol. 32 
