Abstract：Research purposes：A plane model which could analyze the influence of bridge deformation on fastener force was established based on the finite element method and the track-bridge interaction theory. The influence of bridge gradient and longitudinal displacement of pier top on fastener force was analyzed. The adaptive gradient for 32 m simply-supported beam bridge under the load of bridge shrinkage creep, the foundation settlement, temperature difference between one side and another side of pier, train and so on was put forward to provide theoretical guidance for the selection of gradient of bridge.
Research conclusions：(1) The change of bridge gradient and longitudinal displacement of pier top can cause fastener force and the maximum of uplift force increases approximately linearly with the increment of bridge gradient and longitudinal displacement of pier top. (2) For the 32 simply-supported beam bridge whose distance between beam end and adjacent bearing is 0.55 m, when the height of pier is 20m, the maximum gradient is 29‰ to ensure the uplift force of fastener within the limit, while when the height is 40m, the gradient is 20‰. (3) When increasing longitudinal horizontal stiffness of pier or using transition slab or special fastener system between the ends of two beams, the maximum gradient can be appropriately raised. (4) The maximum gradient of bridge ascertained by the uplift force of fasteners can provide the reference for the railway loaction design and the setup of bridge gradient in future.
