LATERAL VIBRATION OF TRAIN-BRIDGE BY MODE METHOD

Chang Shou Chang Jiang Bride is a continuous through steel truss girder bridge. Reducing the degrees of freedom of the bridge is the main problem in its vibration analysis when the train passes through the bridge. The vibration characteristics of the bridge are calculated. Because of the orthogonality of vibration modes the displacements of bridge structure can be expressed as mode coordinates. 8 vibration modes of the bridge are taken as the displacement functions of the spatial vibration analysis when the train passes through the bridge. More than 700 degrees of freedom of the bridge is reduced to 120 mode coordinates. By means of the mode coordinates, the minimum potential energy principle and the "set-in-right-position" rule of forming structural matrices, the vibration equations of vehicle-bridge system are established. By taking the hunting curves of the underframe of the trains on bridge as the excitation source, the amplitude in lower chord of the Chang Shou Chang Jiang Bridge and the Number 41 Bridge are calculated. The results of the Number 41 Bridge are close to the test values. The conclusion indicates the reliability of the method.