The Research On Composite Effect Of Steel-Concrete Beam Of Long-Span Composite Girder Cable-Stayed Bridge

The composite girder cable-stayed bridge has rapid developed in past tens years and has wide application prospect, because it has many advantages and stronger competition ability compared with other type cable-stayed bridge. Therefore, It has the realistic significance to discuss the composite effect of steel-concrete beam that is the main mechanical characteristic of the composite girder cable-stayed bridge. This paper deals with the mechanical behaviors of steel-concrete composite beam and effective width of concrete slab on the axial force and the bending moment together function, based on the past job. The main contents that this paper study is as follows with the main conclusions that are drawn:1. Based on the background of a practical engineering project-Qingzhou Mingjiang Bridge, a spatial finite element model made up of 3-D spar element, beam element and elastic shell element is established. The nonlinear static analysis is performed by using ANSYS in order to analyze the mechanical behaviors of steel-concrete composite beam and effective width of concrete slab under vehicle loads. The distribution of internal force and stress, strain and the effective width of concrete slab is acquired.2. Making use of the method of elastic analysis based on transformed section to research the steel-concrete composite beam on the axial force and the bending moment together function in the usual phase, the theoretic formula of vertical stress and force is derived. The calculated results of the practical engineering project show the accuracy and efficiency of the elastic analysis about the section of composite beam.3. The theoretic method of calculating the effective width of slab and the computing formula of foreign design criterions are introducing. Combined with the practical engineering project, the effective width computed from foreign design criterions are compared with that from the numerical analysis.4.The spatial finite element numerical method is proved correct and the method ofelastic analysis adapt to analyze the mechanical behaviors of composite beam under live load through the survey results of vehicle load experiment.According to the result of research, when the unitary analysis to the composite beam section is proceeded, the effective width of slab can be calculated referring to the British Rules 5400 first, and then composite beam section can be transformed by taking advantage of the elastic analysis. Furthermore, the plane program of the composite girder cable-stayed bridge can be established so that the mechanical behaviors of composite beam can be analyzed simply.