Dynamic Response Analysis Of Long-span Continuous Rigid Frame Bridge Considering The Pile-soil Interaction

Long-span continuous rigid frame bridges have been widely applied in the railways of western mountainous area. With the constant increase of train speed, the dynamic response of vehicle-bridge coupling system could be aggravated, which is certain to pose a threat to driving safety and comfort. Besides, the deformation of foundation might as well increase the vibration severity of vehicle-bridge coupling system; But the effects of pile-soil interaction were usually neglected during the vibration analysis of vehicle-bridge coupling system of long-span continuous rigid frame bridges in previous studies. And as many railway bridges had been damaged to a certain extent in the frequently occurring earthquakes, therefore, it is necessary to investigate the dynamic response of the bridge under earthquake action.This paper, based on Niujiaoping Bridge(main span 192m), which is a long-span continuous rigid frame bridge, finite element models were analyzed in ANSYS code to detailedly discuss the effect of pile-soil interaction on its dynamic responses. Moreover, vehicle-bridge coupling models were calculated to compare the dynamic response of vehicle-bridge coupling vibration with and without earthquake action.Main contents and conclusions are as follows:(1) Two mechanics models of Niujiaoping Bridge were analyzed in ANSYS code, with one had not taken the pile-soil interaction into consideration(model A), the other one had taken it into consideration(model B). Self-vibration characteristics of both model A and B were calculated.(2) The dynamic response of model A and B were analyzed by time-history method, peak values of key sections on the bridge were obtained, the effect of pile-soil interaction was investigated.(3) Taking the combined action of seismic load and train load into consideration, the dynamic response of model A and B were analyzed. Peak values of key sections on the bridge were obtained and the effect of pile-soil interaction in the case of train-running under seismic action was investigated.(4) Based on model B, height of the low-pier was set to five different values. The dynamic response of all the finite element models were analyzed under train load to discuss the effect of pier height difference in the vehicle-bridge system.(5) Based on model B, the dynamic response of the bridge with the change of train speed were analyzed, the effect of train speed in the case of train-running with and without seismic action were summed up.(6) Based on model B, the dynamic response of the bridge with the change of seismic intensity were analyzed, the effect of seismic intensity in the case of train-running with and without seismic action were discussed.