SPAN LENGTH INFLUENCE ON DYNAMIC RESPONSE OF SELECTED BRIDGE UNDER HIGH-SPEED TRAIN

Abstract

The paper presents a methodology of finite element (FE) modelling and simulation of the bridge – track – moving high-speed train system using CAE systems. Two composite (reinforce-concrete – steel) bridges were considered. The span length was equal to 15 and 21 meters, respectively. Bridges selected for the study belong to the proposed series of bridges with the span length of 15 to 27 meters stepped by 3 meters. Full symmetry of the bridges was assumed. RC platform was homogenized since the rebars were distributed quasi-uniformly in the specified platform sections. The FE model of a bridge superstructure consisted of 4-node shell elements (main beams) and 8-node 48 DOF solid elements (reinforced concrete platform). RAIL_TRACK and RAIL_TRAIN LS-DYNA’s modules were applied for simulating the moving train – track interaction. Ballasted track with the rectilinear rail-line axis was taken into consideration. German ICE-3 train running at velocity of 200–300 km/h was selected as a representative for the study. All mass components of the train FE model were treated as rigid bodies. Symmetric vibrations of the train units were assumed with respect to the main longitudinal vertical plane of symmetry of the system. Nodal displacement and longitudinal normal stress in shell elements were registered during the FE analysis. The results were depicted in the form of time histories for selected velocities. In addition, extreme values of vertical deflections and normal stress were compiled and presented a function of train velocity. It allowed to assess the dynamic response of the bridge depending on its span length. Contours of resultant displacement for the RC platform was also presented.