Research Of Temperature Field & Temperature Effect Of Steel Box Girder Without Pavement Caused By The Solar Radiations

Effect of temperature on the impact of the bridge structure has become the consensus of the engineering, Especially for the steel box-grider without pavement which under construction, because of the good thermal conductivities of the steel, temperature affection is more remarkable. The thermal gradient model of steel box girder which is given by our country's general code for design of highway bridges and culverts does not apply to the situation of the bridge deck without pavement. With the widely use of the steel box girder in long-span bridges, a extensive and in-depth research of the temperature field of steel box girder is particularly urgent. In the background of the Hangzhou Jiangdong Bridge and Guangzhou Dongsha Bridge project, the temperature field and effects of temperature action in steel box-girder are researched. The main research content and conclusion of this thesis are as follows:(1). According to the thermal conduct theory and Finite Element Method(FEM), the analytical model in three-dimension is build, loaded and solved with the help of FEM software ANSYS. The result is compared with the data obtained in site measurements. Proved that the vertical temperature distribution in steel box girder section is nonlinear .(2).A series of parametric analysis to show the response of the temperature distribution to the variation in parameters. The study shows that the absorptivityαhave the most significant effect on temperature distribution, followed by wind speed v , the minimum is the emissivityε.(3).By the analysis of measured datas , temperature field changes with time of the steel box girder without pavement is obtained .At the same time, the measured data also accumulate data for formation the temperature gradient of steel box section in our country.(4).Piecewise function was used to fitting temperature changes of the top and bottom slab of steel box girder, derived a function that can predict the temperature change of steel box the top and bottom within one day.(5). Exponential function was used to fitting the vertical temperature differences curves of steel box girder, vertical positive temperature differences curve of steel box girder without pavement in several regions of our country was obtained.(6).With the use of symmetry, half-bridge mode of Hangzhou Jiangdong Bridge during incremental launching construction was established, loaded and solved , found that thermal stress and the temperature deformation of the steel box girder caused by the temperature gradient in construction can not be ignored, we must be taken into account the errors of assembly line caused by the temperature gradient during incremental launching construction and amendment it .