風載下列車行駛在大跨斜張橋之脫軌分析

Wind-induced vibrations of long-span cable-stayed bridges are prone to the derailment problems of a train moving on flexible bridges. Considering the wind-train-bridge coupling system, a vector form intrinsic finite element (VFIFE) theory is proposed to develop a 3D vehicle-bridge interaction (VBI) model that can take derailment effects into account, in which the vehicle and bridge are discretized into a series of mass points that are connected by massless springdamping units for structural modeling of the VBI system. To carry out derailment analysis of the wheel-sets moving on tracks, their contact points are determined by the geometric contact relationship of wheel-rail system associated with the Hertzian contact and Kaller creep theory. In addition, the stochastic wind acting on the vehicle-bridge system is simulated as pseudo-static wind loads with buffeting forces for dynamic analysis of the wind-VBI system. From the present study, the VBI-VFIFE model is applicable to derailment analysis of a train moving on a bridge in cross winds once the leaving or jumping phenomena between the wheel-set and tracks occur. From the present study, it is concluded that (1) as a train enters into a two-span cable-stayed bridge made of fully welded steel (330m) and pre-stressed concrete (180m) girders, its derailment risk on the steel girder would rise significantly due to wind-induced large vibrations on the steel deck; and (2) the jumping phenomena of moving wheel-sets on the bridge occur at the transition between the welded steel and PC girders.