DYNAMIC RESPONSES AND TRAIN RUNNING SAFETY OF RAILWAY CABLE-STAYED BRIDGE UNDER EARTHQUAKES

To investigate the train-bridge coupling dynamic responses and train running performances of high-speed railway cable-stayed bridge system under earthquake, a single tower cable-stayed bridge (112 m+80 m+32 m) with channel section, which is located in Changsha part of Hangzhou-Changsha dedicated passenger line, was taken for a case study. A spatial dynamic analysis model of train-track-bridge coupled system subjected to earthquakes was established by computational analysis software TRBF-DYNA. The seismic responses of track-bridge subsystem were calculated by the equivalent load method. The relative seismic responses of rail were transformed to the dynamic response in the absolute coordinate system through considering pseudo-static displacement component. Finally the seismic action was applied to the train through the spatial wheel-rail rolling contact model. The variations of bridge-train dynamic responses and train running safety were analyzed under different running speeds and seismic intensities. The results show that seismic excitations have significant influence on the train running safety, and the safety velocity thresholds of train corresponding to the frequent earthquake intensities of 7, 8 and 9 are respectively 200 km/h, 180km/h and 140 km/h according to Chinese national code. Meanwhile, according to the wheel-rail contact judgment criteria, the wheel-rail relative displacements are still within safety range under frequent earthquakes with intensity of 7, 8 and 9 when the range of train speed is from 80 km/h to 240 km/h.