Research purposes: With the continuous speed—raise of train,the analysis of the dynamic response of steel truss bridge of the existing railway line has reference significance to accurate evaluation of design of阳ilway bridge and also to maintenance and reinforcement of the existing railway line.
Research conclusions: Regarding train and bridge as one composite system,by means of the principle of total potential energy with stationary value in elastic system dynamics and the”set—in—fight—position”rule for structural matrices. the vibration equations of vehicle—bridge time varying system are established.This method is more convenient than the finite elements.The vibration responses of a simply—supported truss bridge are calculated when DF4 locomotive hauling 25 C62 freight wagons and DFl 1 locomotive hauling 1 8 passenger coaches to pass this bridge at the different speeds.It Can be seen from the analysis that the traffic safety is guaranteed and the comfortableness and stability of train reach at the standards.It shows that the bridge has sufficient lateral and vertical stiffness.