Deformation Analysis And Construction Control Of Box Section Beam Element Considering Shear Effect

In recent years,steel box girder is more and more widely used in long-span cable-stayed bridges,especially the section form of flat steel box girder is more and more common.Because the problem of shear deformation of flat steel box girder is more prominent,the research on shear deformation of steel box girder has become the focus of scholars at home and abroad.In the beam element theory,the key to consider the shear deformation is the non-uniform distributed coefficient of shear stress.In this paper,based on the relevant theory and the practical engineering background,the non-uniform distributed coefficient of shear stress of box section is studied,the calculation formula of non-uniform distributed coefficient of shear stress suitable for thin-walled section is derived,and a simplified method with high accuracy for calculating the non-uniform distributed coefficient of shear stress of complex box section is given.The main contents of this paper are as follows:(1)In this paper,two kinds of beam element theory and calculation method of the non-uniform distributed coefficient of shear stress which are commonly used in engineering considering the influence of shear deformation are described.(2)Based on the energy principle and the shear flow theory of thin-walled structure,the calculation formula of the section the non-uniform distributed coefficient of shear stress of thin-walled structure is derived.According to the comparison between the calculation results of the box section and other common calculation theories,and the verification of the solid model of the steel box girder plate shell element,it is concluded that the shear effect of the flange plate part of the flat box section with large aspect ratio cannot be ignored.(3)This paper discusses the change rule of s the non-uniform distributed coefficient of shear stress,and draws a conclusion:the non-uniform distributed coefficient of shear stress of web plate is mainly controlled by the ratio of section area to web area;the thickness of web and flange plate almost does not affect the non-uniform distributed coefficient of shear stress of flange plate;the greater the thickness difference between upper and lower flange plates,the greater the total non-uniform distributed coefficient of shear stress of upper and lower wing plates.(4)According to the relationship between the non-uniform distributed coefficient of shear stress and the section parameters,a simplified method for calculating the non-uniform distributed coefficient of shear stress of the complex box section is proposed.After the verification of 15 kinds of steel box sections of Jiayu Yangtze River Highway Bridge,it is proved that the method has high accuracy and can greatly reduce the calculation error of the common method.(5)Taking the actual project of Jiayu Yangtze River Highway Bridge as an example,the paper points out the importance of shear deformation of steel box girder in the linear control of bridge construction monitoring,and introduces the effective measures taken by Jiayu Yangtze River Highway Bridge in the process of steel box girder fabrication,pre assembly and positioning to ensure the accuracy of alignment control.