Research On Sunshine Temperature Difference Effect Of Concrete Box Girder Based On Midas/Civil

With the rapid development of social economy,the construction of long-span prestressed concrete continuous girder bridge is increasing in China.Concrete box girder bridges are strongly affected by temperature changes and solar radiation in the natural environment,and the thermal conductivity of concrete is poor.Non-linear temperature differences will occur inside the structure.Such non-linear temperature differences will cause large temperature deformation and temperature stress of the concrete box girder.The research shows that temperature stress is one of the important factors that cause cracks in box girder structures.The temperature difference effect of sunlight directly affects the durability and safety of concrete box girder bridges.The temperature gradient model of concrete box girder in the codes of different countries is obviously different according to different regions and climates,and the temperature gradient of each country is a general model.Although the railway codes in China take into account the effects of atmospheric transparency and geographical latitude,the regulations are the most unfavorable In this case,The purpose of this article is to provide a method that can calculate the real-time temperature gradient of any concrete box-girder bridge.In this paper,a(64+112+64)m prestressed concrete continuous beam bridge in Guangdong Province is taken as the engineering background,and the effect of sunlight temperature difference is studied in depth.Select the key section to observe the temperature field on site and calculate the temperature change value,and analyze the temperature field distribution of the box girder section and the temperature change rule along the thickness of each plate.The midas Civil finite element software is used to simulate the transient temperature field.First,the heat transfer process and boundary conditions are analyzed through the theoretical knowledge of disciplines such as general astronomy,meteorology,and heat transfer.The Python programming language can be used to calculate any time Considering the temperature load program of temperature environment,bridge direction,bridge position and box girder structure,the simulation simulation value is compared with the measured value to verify the reliability of the calculation program and calculation method.Quantitative analysis of the distribution factors affecting the temperature field of concrete box girder including bridge trend,solar radiation intensity,concrete thermal conductivity,concrete specific heat capacity and box girder cross-section height were performed to determine which factors played a leading role.In order to calculate the temperature effect more accurately,a temperature gradient curve suitable for the Guangzhou area was fitted based on experimental observations and finite element calculation temperature field data.Calculate and compare the temperature effects under three conditions: fitted temperature gradient model,Chinese railway code and British code temperature gradient model.The research content of this paper can provide reference for the effects of sunlight temperature difference of concrete box girder and temperature gradient model in Guangzhou area,and provide guidance for the calculation of temperature effect and construction phase of concrete box girder.