Study On Temperature Field Of Prestressed Concrete Box Girder In Plateau Area

The box girder has been widely used in recent years because of its good mechanical performance and the overall performance.with the central "Belt and Road Initiative " to promote the guidance of the western development strategy,high pier and long-span prestressed concrete box girder bridge has a lot of construction in Plateau area.Therefore,it is of great significance to study the temperature field of box girder,especially the temperature gradient model of box girder in high and cold regions,to ensure the safety of box girder.In order to study the temperature distribution characteristics and temperature gradient model of the prestressed box girder in the plateau area,this paper takes two high piers and large span prestressed concrete continuous box girder bridges in Ganzi state of Sichuan Province as the engineering background,and based on the related theories of solar physics,heat transfer and thermodynamics and so on.The thermal boundary condition of box girder temperature field is established and used to study the temperature field of high altitude box girder bridge.The temperature of box girder is measured by using the temperature sensor in the field,and the vertical temperature gradient model of different countries is compared and analyzed.The temperature difference curve along the height direction is fitted on the basis of the measured data.The temperature distribution of the box girder is mainly influenced by the solar radiation.Considering the high altitude of the plateau and the high transparency of the atmosphere,the influence of altitude on the altitude of the plateau is studied.The accuracy of the calculation of the radiation formula is verified by the comparison of the field radiometer.In order to verify the accuracy of the temperature test data of the box girder,and obtain the temperature gradient model of the high altitude box girder.The temperature field of the prestressed box girder in the plateau area is modeled and analyzed by the Fluent software and the GUI command of the ANSYS software.By checking the coincidence of theoretical and measured values,using the least square method to fit the vertical most unfavorable temperature gradient of the box girder,the temperature gradient model of the box girder in the plateau area is obtained.It is proved that the finite element simulation and analysis of the temperature field of the box girder in the plateau area is feasible.enough accurate results to meet the engineering practice can be got.In addition,field data indicate that the most unfavorable temperature distribution of box girder is mainly in summer.Considering the influence of altitude,longitude and latitude,bridge location,solar radiation and ambient temperature on the bridge,the gradient mode is obtained from field measurement and simulation analysis is compared.The vertical temperature gradient model of the large span prestressed concrete box girder in Yajiang County,Ganzi,Sichuan province is obtained,which provides theoretical basis and field guidance for the bridge design and construction.