Dynamic interaction of long suspension bridges with running trains

This paper presents an investigation of dynamic interaction of long suspens ion bridges with running trains. A three-dimensional finite element model i s used to represent a long suspension bridge. Each 4-axle vehicle in a trai n is modelled by a 27-degrees-of-freedom dynamic system. The dynamic intera ction between the bridge and train is realized through the contact forces b etween the wheels and track. By applying a mode superposition technique to the bridge only and taking the measured track irregularities as known quant ities, the number of degrees of freedom (d.o.f.) the bridge-train system is significantly reduced and the coupled equations of motion are efficiently solved. The proposed formulation and the associated computer program are th en applied to a real long suspension bridge carrying a railway within the b ridge deck. The dynamic response of the bridge-train system and the derail and offload factors related to the running safety of the train are computed . The results show that the formulation presented in this paper can well pr edict dynamic behaviors of both bridge and train with reasonable computatio n efforts. Dynamic interaction between the long suspension bridge and train is not significant. (C) 2000 Academic Press.