Operation safety of high-speed trains is dependent on their vibration characteristics, which vary with bridge deformation. This paper studies the influence of bridge pier settlement and girder creep camber, which are two typical types of long-term bridge deformation, on the vibration of high-speed trains. To this end, an analytical approach is presented to link the bridge deformation with railway track deformation; the track deformation is used to analyze the vibration of the CRH2 high-speed train in China. The vibration analysis results are validated using the in-situ measurement data. The present study shows that bridge pier settlement greatly affects the vertical acceleration, derailment coefficient and wheel unloading rate of the high-speed train; incorporating bridge girder camber aggravates the vibration of the train–bridge system. The threshold of bridge pier settlement is suggested to be 11.1[Formula: see text]mm for trains moving at 350[Formula: see text]km/h with regard to the code-specified vibration limit. This study has significant implications for the design and operation of high-speed railways.

In this study, a refined finite element model was built that represented the structural and mechanical properties of railway bridges. A coupled vehicle-bridge vibration model was established to simulate the dynamic behavior of the bridge under moving trains. Field tests were then conducted to determine the free vibration characteristics as well as the strain, displacement, and acceleration of the bridge structure under trains moving at different speeds and braking at a specified position from a set speed. The dynamic response of the bridge was found to increase with the train speed, but the main beam of the bridge was more affected by a train braking than the one passing over it. Both the bridge and vehicle were found to meet the relevant requirements for safe design and operation, with the train exhibiting good running safety and smoothness, and the bridge structure showing sufficient stiffness and dynamic performance. Based on the field measurements and analytical modeling, it can be concluded that the use of appropriate equipment and the selection of a suitable layout for the sensors permit the assessment of the dynamic behavior of the bridges from vibration measurements. This indicates the potential for the continuous health monitoring of the railway bridges that may be sensitive to the vehicle-bridge interaction.

The structural mechanism existing in the V-shape pier-girder joint in long-span V-shape rigid frame composite arch bridge is complicated, especially for the case in the Xiaolan Channel long-span major bridge project, which requires comprehensive research on the local stress and nonlinear behavior after cracking through model test. Using nonlinear space finite element model, the local stress and post cracking nonlinear mechanical behaviors at the V-shape pier-girder joint are studied. In this paper, the design principles, loading modes, procedures and arrangement of gauging points applied in the model are introduced at first. Comparing the experimental results with the theoretical values, the local stress distributions of the V-shape pier-girder joint under different loading conditions are obtained. Furthermore, the nonlinear behavior of the V-shape pier-girder joint is investigated by analyzing the relationships between loads and reinforcement strains in negative moment area and the relationships between loads and deflections. The study shows that the load transfer in V-shape pier girder joint is reasonable. The joint has good ductibility, post-deformation and residual carrying capacity. The design of the V-shape rigid frame composite arch bridge meets the criteria. It is also expected that the results presented in this paper would be useful as references for future research and design of V-shape rigid frame composite arch bridges and joints.

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