Research on the Train-Bridge Coupled Vibration and Dynamic Performance of Steel Box Hybrid Girder Cable-Stayed Railway Bridge

Based on the Yongjiang Bridge, this paper used the numerical calculation and the field dynamic load test to study the coupled vibration and dynamic response of the steel box hybrid girder cable-stayed railway bridge. Each vehicle in the train was simulated with 31 degrees of freedom, and the oscillatory differential equation of vehicle-bridge coupling was established by MATLAB software. Afterwards, the field tests were also conducted to determine the free vibration characteristics as well as the strain, displacement, and acceleration of the bridge superstructure under trains moving at different speeds and braking at a specified position from a set speed. According to the dynamic load test and Vehicle-Bridge Coupling Vibration analysis, the following conclusions are obtained: (1) The calculated results of vehicle-bridge coupling vibration agreed well with the measured ones, and the program could be used to analyze the dynamic performance of Railway cable-stayed bridges with steel box composite girders. (2) The measured first-order natural frequencies of transverse, vertical and longitudinal vibration were 0,39 Hz; 0,49 Hz and 0,88 Hz, respectively. The dynamic coefficients are 1,04 – 1,13, the maximum lateral and vertical accelerations are 1,10 m/s2 and 1,11 m/s2, and the maximum derailment coefficient and load reduction rate are 0,55 and 0,39, respectively. These data showed that the dynamic parameters of bridges and vehicles met the requirements and had good stiffness and dynamic performance. (3) This paper, using the frequency limit of simply supported beam to restrain the natural frequencies of cable-stayed bridges is not appropriate, and it is necessary to propose the natural frequency limit value of cable-stayed bridge