Analysis On Stressing State Characteristics Of Transverse Large Cantilever Box Girder And Curved Box Girder Bridge Models

At present,box girder bridge has been widely applied because of light weight,high torsional rigidity and easy installation.However,the traditional theory and method can not accurately predict the bearing capacity of the box girder bridge because of its uncertain ultimate bearing state.At the same time,there are many problems such as many cracks,large deformation and so on in the actual project.The current analysis theory and method also presents various deficiencies.Therefore,two typical box girder bridges,i.e.the transverse large cantilever box girder bridge and the curved box girder bridge,are re-modeled through the theory of structural stressing state in this paper.The specific working behavior characteristics of the box girder bridge during the bearing process are revealed,and the failure criteria of the structure and the corresponding characteristic loads are proposed.The main research contents are as follows:(1)This paper briefly describes the concept of structural stressing state theory,and quantitatively describes the stressing state of the box girder bridge with the generalized strain energy density of the structure as the basic parameter.Then,M-K criterion is used to distinguish the mutation characteristics of the structural stressing state characteristic parameters of the box girder bridge in the process of load evolution.This paper reveals the general working characteristics of box girder bridge structure——the starting point of structural failure,which is defined as the failure load of the structure.At the same time the elastic-plastic branch point of the structure is also revealed and the corresponding load is defined as the elastic-plastic branch point load of the structure.(2)Based on the response data(strain,displacement,etc.),the stressing state mode of box girder bridge,the stressing state sub modes of different internal force types and their characteristic parameters are constructed.The curves of these modes and parameters with load evolution are drawn and the stressing state characteristics of the box girder bridge before and after the elastic-plastic branch point and the failure point are investigated to reveal the difference of the mecha nical properties in different working stages.(3)The numerical shape function method is used to expand the experimental data of the bridge to obtain more detailed bridge test information,that is,the response of the unmeasured area.The stress and strain fields of the section are used to represent the stressing state mode of the structure,and the stressing state mode and characteristic parameters of the internal force are formed.The evolution characteristics of them with the load are investigated to further reveal the general working characteristics of the box girder bridge and verify the regularity of the failure point and the elastic-plastic branch point.Then,the correlation analysis of the different internal forces of the box girder bridge is carried out,that is,the coordination working mechanism analysis of each component of the box girder bridge under the structural stressing state is carried out to reveal the coordination working performance of each section of the box girder bridge.(4)Through the comparative analysis of the stressing state characteristics of the transverse large cantilever continuous box girder bridge and the curved box girder bridge,the common working characteristics of the box girder bridge in the bearing process are revealed.Then,the general rules of structural failure are explored,and the universal applicability of the theory of structural stressing state is verified.