Analysis And Research On Sunshine Temperature Difference Effect Of Arch Single Tower Hybrid Cable-stayed Bridge

Bridge structure will be affected by many external factors in the process of construction and operation,such as temperature,wind,dynamic load and so on.The influence of temperature on bridge structure is more obvious,even greater than the influence of external dynamic load.Due to the long-term exposure of the bridge structure to the external environment,the bridge structure will inevitably be affected by sunshine radiation and external temperature changes,resulting in uneven internal temperature field,especially for steel-concrete composite girder bridge,the temperature will have a great impact on the main girder line,cable force,bridge tower offset and internal force of each structure in the construction stage and completion stage of the cable-stayed bridge.Therefore,it is necessary to study the influence of temperature on bridge structure in order to find the best construction time.In this paper,Jiangwan Bridge is taken as the engineering background.Through the analysis and comparison of field temperature monitoring and Midas Civil software modeling,the following conclusions are drawn:1.Briefly describe the formation of temperature field,the classification and characteristics of temperature load and three basic methods of solving temperature field.The boundary conditions of temperature field of cable-stayed bridge and three applicable calculation methods of solar radiation intensity,radiation heat transfer coefficient and convection heat transfer coefficient are analyzed.2.Through the temperature collection and analysis of each component of the bridge structure on site,it is concluded that the temperature field of the main beam and the bridge tower changes periodically under sunshine temperature,in which the temperature increases by 8.6℃ within 0.4 m along the height direction of the box girder due to solar radiation.Compared with the stipulation that the temperature difference changes to 8.5℃ within 0.1 m for the concrete girder bridge with the thickness of the asphalt concrete pavement layer of 0.1 m in the General Specification for Design of Highway Bridges and Culverts in China,the surface temperature difference calculated in this paper is small and safe.The data were fitted and the temperature distribution curve function suitable for the most unfavorable temperature in the region was proposed.3.The finite element software is used to establish the construction stage model and the full-bridge model,and the influence of temperature effect in the construction stage on the deflection of the main beam,the cable force and the displacement of the bridge tower is analyzed first.Then the deformation law of tower,cable and main girder of steel-concrete cable-stayed bridge under the action of sunshine temperature difference is analyzed.It is concluded that the temperature difference between cable and girder in construction stage and completion stage has the greatest influence on the displacement of main girder,cable tension and tower,and the overall lifting temperature is the smallest.4.By comparing the internal force changes of each part of the bridge structure under four kinds of temperature effects and dead load,the sensitivity of different parts of the bridge structure to temperature changes is obtained.The bending moment of the bridge structure is more sensitive to temperature changes,and the shear force and axial force are less sensitive to temperature changes.It provides reference for the design and monitoring of similar bridges.