Sunshine Temperature Difference Mode And Structural Response For Cable-stayed Bridge With U-shape Beam

Sunshine temperature difference is a very important action in the design of bridges, and its structural response has a significant impact on the forces distributing in the bridge-track system. In most design codes, the sunshine temperature difference mode is applicable for the normal box girder or T-shape girder but seldom for the U-shape girder. Meanwhile, the influence of sunshine temperature difference was not considered in the existing code about track-bridge interaction.Based on a cable-stayed bridge with U-shape girder on the new-built Hangzhou-Changsha high speed railway, the suitable sunshine temperature difference mode of U-shape beam was fitted and its influence on the structure and the continuous welded rail was analyzed. The main works of this paper are as follows:1. Based on the theory of heat transfer, solar physics and so on, a plan element mode of the U-shape section was established, and the boundary conditions of heat transfer were simulated. Then the thermal field in the U-shape girder was analyzed and a sunshine temperature difference curve for U-shape girder was proposed (simplified as "fitted curve").2. Under different load mode of sunshine temperature difference, the structural response of the cable-stayed bridge was analyzed. The results indicate that the fitted curve is more applicable for the U-shape girder, while the curve in China Railway Standard is not safe for the design of this bridge.3. In order to analyze the track-bridge interaction under sunshine temperature difference, adopting the ideal elastic-plasticity resistance model to simulate the longitudinal resistance between rails and the girder, an integrative bridge-track system model was established, including the tower, cables, beam, track, piers, pile foundations, the adjoining simply-supported beams and subgrade section. The results show that sunshine temperature difference has great influence on the longitudinal forces and displacement in rails, so it should be taken into consideration during the design procedure.