Analysis Of Long Span Pc Continuous Box Girder Bridge Temperature Field And Its Effect

In recent years, with the development of high grade highway and stereoscopic transportation in cities, bridge development has entered the unprecedented high tide period. Among them the box girder occupies important position in developments of the long span-span PC beam bridge with its good section-form. but in construction and application of some domestic and international bridge, some serious cracks have been discovered, which caused very terrible results. The study had shown that the thermal stress caused by solar radiation was the main factors which induced this cracks. For concrete structure, the change of temperature because of solar radiation varying rapidly is greater influence than the annular air temperature load which changes slowly. It has been proved by examples of engineering practice that temperature fields did great effect on the stress and line deformation of long-span PC continuous box girder bridges. Therefore, it is necessary to get temperature mode and its effect on the stress and line deformation in one region of our country by theories and experiments. It can be used in the bridge design, which makes a reasonable time to construct, sprinkle concrete and control appropriate temperature on key constructing processes.On the basis of analyzing the kind of methods above and based on Suzhou Xiegang bridge ,this paper will make a research from four aspects as following:1. Adopt the spot-measure method, by measuring the temperature of temperature-feeling machine of pre depositing in the box section, I can get the varying temperature data of different time in box sections, then make use of these temperature test datas, figure out the variety regulation of temperature distribution along the direction in box section with the nerve network method, then I get temperature fields of box section along the high direction;2. According to the examples of engineering practice, we can build up temperature calculating modes of box section and then calculate temperature fields of box section bymeasuring the boundary conditions and restricting conditions;3. Finally ,I will compare the spot measure results with the results which calculated by an analysis software ANSYS ,so I can verify the temperature step-mode. then I can further make sure the temperature mode and its effect on the stress and line deformation in one region of our country.4.The paper also introduced the method of how to calculate the temperature stress in box girder with two-dimension model. Additionally, the deflection of the box cantilever induced by differential temperature in construction is also analysed.