The Self-Vibration Analysis On Qinshen Railway Box Girder Bridges

Based on the Euler's beam theory and Timonshenko's beam theory, the basic knowledge of finite element theory and the drawings of Qinshen's high speed railway box girder bridge, the self-vibration frequency of the high speed railway box girder bridge is analyzed and studied.A program, which can be used to analyze the self-vibration frequency of box girder bridges, is compiled using Fortran language. The beam element and solid element are included. Also the effect of shear deformation on self-vibration can be calculated too using the program. At the mean time, Algor, a famous FEA program, is used to verify the results obtained by the program compiled. The results are proved to be correct.At last the results obtained are compared with those of T-beams, which shows: 1) the base frequency of T-beam and box girder bridge is different not only in the value but also in vibration direction. The base frequency of T-beam is the lateral bending vibration, while in box girder bridges is vertical bending vibration. 2) The value of base frequency, which is the first order vertical-bending vibration, is bigger in box girder bridges than those of T-beams. It shows that the vibration performance of box girder bridge is better than T-beams. 3) When considering the shear deformation of beam, the vibration frequency calculated by is bigger than those not considering the shear deformation. The difference is big and cannot be neglected.