Study On Temperature Effect Of Beam Bridge Based On 3D Finite Element Method

Bridge temperature effect research has always been one of the key concerns in bridge design,construction and maintenance.Excessive longitudinal and transverse temperature gradient will produce excessive temperature stress,which will lead to cracking of the beam,and have a great impact on the safety,durability and applicability of the structure.In recent decades,there have been many studies on the temperature effect of bridges,most of which are simplified to two-dimensional analysis.These studies have better accuracy for conventional structures under most working conditions,but the accuracy of some complex structures and working conditions(such as complex temperature field)is difficult to meet.The calculation theory of bridge temperature effect under three-dimensional temperature field is complex.At present,there is no theoretical guidance for the conceptual design of bridge temperature effect structure.The two-dimensional analysis method used by designers and researchers will lead to unsafe structure for studying temperature effect.On the other hand,the location of bridges is scattered,and the necessary meteorological temperature data are usually lacking,which makes it difficult to survey in the early stage.Therefore,it is necessary to establish a reliable theory to calculate the meteorological data in this area,and then obtain the temperature field parameters,so as to provide basic parameters for high-precision temperature effect analysis.Therefore,this paper will break through the limitation of plane analysis when calculating temperature effect,give the guidance of bridge temperature conceptual design,and get a whole set of 3D bridge temperature effect calculation method.The main work is as follows:(1)According to the theory of solar astronomical model,the radiation of three-dimensional model of concrete beam bridge under different bridge sites(longitude,latitude and azimuth)is calculated.Then the temperature distribution of the whole bridge is obtained in the finite element software ABAQUS by using the radiation value as the boundary,and the temperature gradient at the time of maximum temperature difference is fitted in the form of exponential function.(2)The solution process of three-parameter moment distribution method is deduced.The section height,mid-span to mid-span ratio and bearing height to span ratio are selected as key parameters,and the transfer coefficient,distribution coefficient and basic bending moment are calculated to supply and demand solutions.In order to verify the accuracy of the method described in this paper,the error between the structure calculated by this method and that calculated by Midas and structural mechanics solver is only 2%,which proves that the method is accurate and reliable.(3)The plane strain method is used to calculate the temperature self-stress of bridge,especially the transverse temperature stress and the analysis of its main influencing parameters.The fitting temperature gradient formula,railway bridge gauge and highway bridge gauge are calculated theoretically,and the 3D model of beam bridge is compared by using finite element simulation software ABAQUS.The results show that the error is very small.Finally,the calculation results of temperature internal force of Mei'an Bridge are given by using moment distribution method of variable cross-section continuous beam.