Research on Dynamic Behaviors of 32m Prestressed Concrete Simply Supported Box Beam in High-speed Railway

2m simply supported box beam is a standard beam which has been widely used In Chinese high-speed railway. So,it is necessary to do an indepth analysis of the dynamic behaviors parameters(include the natural frequency of beam, dynamic deflection, lateral amplitude, vertical amplitude and vertical acceleration) of 32m girder. In this paper, the theoretical analysis model of 32m simply supported box beam were built and the dynamic response, the potential resonance frequency, the resonance speed and super-harmonic resonance speed of it subjected to the CRH multiple unit were researched in detail. The comparisons between the calculated results and measured results were made. The research results show that, (1) The dynamic behaviors of girder is good. The lateral and vertical rigidity of girder are much more than the limits specified by relevant code and design file. (2) The resonance of 32m girder would not occur at current operating speed. The peaking effects of the vertical dynamical response at mid-span of 32m girder would appear when the speed of CRH multiple unit is close to the super-harmonic resonance speed,however, the measured value of the vertical dynamic response were still small because of the low incentive energy of CRH multiple unit with low mass and short marshalling. (3)Under the present designed lateral and vertical rigidity of girders,the tested dynamic response of different 32m simply supported box beams arranged with continuous equal span are similar. The periodicity irregularity effects of it did not appear.