Temperature Field And Temperature Gradient Effect Analysis Of Long-span Prestressed Concrete Continuous Box-girder Bridge

The occurrence of cracks is an important reason for the durability of concrete structures.There are many factors that affect the cracks of the concrete bridge,in which the temperature difference load is an important factor in the crack of the bridge.China's vast territory,the climate of different regions is very different,and China's current highway bridge and culvert design specification binds that the country's road bridges of different regions all use the same temperature gradient model.In the specification,it does not distinguish the differences of bridge structure,and the cross-sectional.In this paper,based on the long-term observation,conducted further research to the temperature field of box-girder.And the parameters of the calculation of the finite element analysis and analysis of the temperature field of box-girder are carried out.The main contents and results of this paper are as follows:(1)Based on the construction monitoring project,the temperature field of the relying project has been monitored for a long time.The variation law of temperature field of box-girder in sunshine,cooling and rain and snow weather is analyzed.(2)According to the theory of solar physics,general astronomy and heat transfer,the heat transfer boundary conditions of concrete box-girder under sunshine are analyzed.Using the measured local meteorological data,the finite element analysis software ANSYS is used to analyze the temperature field of box-girder State analysis.Finally,the calculated value is compared with the measured value to verify whether the model is correct.(3)After comparative analysis,There is a large deviation between the calculated value and the measured temperature of the roof and bottom.The calculated temperature field of the other board is similar to the measured temperature field.Through analysis,find out the parameters which may influence the temperature field of box-girder.and change the parameters of the box girder to observe the change of temperature field of box girde.Finally,the value of the parameters is optimized.It provides advice on the calculation of the temperature field for some areas in which it is not possible to measure the sunshine temperature field in,but only to refer to the local meteorological conditions.(4)The most unfavorable temperature difference state is selected from the data of longterm observation and analysis,and the vertical temperature gradient and lateral temperature gradient are fitted respectively to provide reference for the temperature difference load of highway bridge which will be built on Huaihe River.(5)Calculate and analyze the temperature effect caused by the vertical temperature gradient in different specifications.This paper divided two states: maximum cantilever and bridge,the temperature stress and displacement of different vertical temperature gradient are analyzed and compared.