NUMERICAL ANALYSIS ON THE VIBRATION CHARACTERISTICS OF THE ELEVATED BOX GIRDERS IN URBAN MASS TRANSIT

摘要

In order to study the vibration response of the elevated box girders in urban mass transit subjected to the train, 3D vibration model of simply supported girder are established by FEM.The dynamic response of the box girder can be obtained with the train rtmning at a velocity of 60, 80, 100and 120 km/h.The modal analysis results show that mode shapes of which natural frequencies is higher than 10 Hz present a deformation in section, and the vibration pattern of box girder appear as the bending vibration of composed plate elements gradually.The time domain analysis result shows that when the train pass, the distribution of vibration appear as a phenomenon that the acceleration amplitude of flange is the largest, the one of web is the second, and the one of deck and bottom plate is the smallest in all.The vibration levels of rail, slab, deck, flange, web and bottom plate range of140～160 dB, 110～120 dB, 110～120 dB, 115～130 dB, 110～125 dB and 105～115 dB respectively, and increase with the improvement of train speed.