DYNAMIC BEHAVIOR OF RAILWAY BRIDGES UNDER UNSPRUNG MASSES OF A MULTIVEHICLE TRAIN

When a multi-vehicle train passes over a railway bridge, it is expected that a parametrically excited vibration occurs in the bridge, according to the change of the additional mass distribution caused by the unsprung masses of vehicles. A Shinkansen vehicle of the Japan Railway Co., Ltd, was chosen as an example of a railway vehicle and the dynamic stability of a railway bridge under an idealized multi-vehicle train was investigated in this study. The dynamic stability of girders under a sequence of equidistant concentrated load masses was estimated for vertical vibration and horizontal flexural-torsional vibration and the behavior of a girder under a load sequence of equidistant half-vehicle models was investigated by numerically integrating the equations of motion of the girder and the half-vehicle models. The influences of the masses of an axle, its wheels and the truck frame as an additional concentrated mass on the girder were revealed from comparisons of the above results. © 1990.