Study On Temperature Field And Temperature Effect Of Long-span Precast Concrete Box Girder

With the effort of solar radiation, long-span concrete box girder in the natural environment will have a non—linear temperature field and a great temperature stress, which has seriously affected the structure of security and durability. According to Xiangshangang PC continuous box-girder bridge of Ningbo city Zhejiang province, the paper uses continuous observation method to observe temperature field in several month. Expectations that we can get accurate temperature field and temperature effect of this bridge.At first, the paper introduces the research of the effects of temperature, and in detailed introduction world some main national standards. Introduce finite difference method and finite element method and the effects of temperature calculation method of concrete box-girder temperature field. According to the data, the paper exhaustively analyzes the change regularity for temperature field in each concrete box-girder components in solar radiation. this paper also precedes the regression analysis to get the Fitting's temperature gradient function. The temperature field and temperature effect are also simulated by the ANSYS according to the parameters collected on site. Thus, the characters of the temperature field and the fitted temperature gradient are proved to be available. And the accuracy of the temperature field characters and the measured temperature effect data is satisfactory.Secondly, according to the thermal conduction theory and finite element method, the model of this bridge, which considers the 3rd-type thermal boundary conditions, is built to analyze the effect of cementitious hydration heat. The unsteady-state thermal solution is done to conclude the rules of temperature development for this structure and to predict the temperature distribution under field conditions. Then some measures are commended to control the structural temperature.In full consideration of engineering environment conditions and useing theory knowledge and calculation software,this paper get the temperature field and temperature effect which is very match to this bridge. All this work provide the reliable basis to engineering construction and embodies the considerable practical value.