Study On Mechanical Behavior And Mechanism Of Steel-Concrete Composite Section Of Hybrid Beam Cable-Stayed Bridge

Cable stayed bridge is one of the most competitive types of long-span bridges.Hybrid girder cable-stayed bridge is the preferred form of cable-stayed bridge with span ratio is small,because a single concrete beam or steel beam will produce negative reaction on the pier top of side span,and will cause deflection on the tower top and main span,while hybrid girder can use side span concrete to balance the weight of main span which can not only better meet the stress requirements of the structure,but also achieve the purpose of economic rationality and construction.Hybrid beam cable-stayed bridge has been widely used in highway bridges because of its strong spanning capacity,high bearing capacity and superior economic performance.The steel-concrete composite section is an important link in the construction of hybrid beam cablestayed bridge.It is necessary to have a deep understanding of the structural form and mechanical characteristics of the steel-concrete composite section.As a key and difficult point in the design of highway hybrid beam cable-stayed bridge,the steel-concrete composite section has various structural forms and complex structural stress.It is of great practical significance to study its stress characteristics and transmission mechanism for the construction of highway hybrid beam cable-stayed bridge.This paper takes Shaoguan Jiangwan bridge as the engineering background,based on the current research at home and abroad,this thesis establishes the local finite element model of the steel-concrete composite section,and carries on the numerical simulation to its stress,verifies the safety of the steel-concrete composite section of Jiangwan Bridge,and probes into the influence of the design Parameters of the composite section on its stress and transmission performance through the control variable method.The main contents of this thesis are as follows:1.The rise of hybrid beam cable-stayed bridge and the research status at home and abroad are described.The structural form and classification of the steel-concrete composite beam joint section are introduced.Based on the Shaoguan Jiangwan Bridge,the structural form and reasonable position of the steel-concrete composite section of hybrid beam cable-stayed bridge are explored.2.Through the finite element software MIDAS civil,the whole tie model of Jiangwan Bridge is established,and the static analysis of Jiangwan Bridge in the completion stage is carried out,and the stress conditions under different working conditions are obtained,and the internal forces and boundary conditions at both ends of the steel-concrete joint section of Jiangwan Bridge are extracted,so as to provide basic data for the local model analysis of the steel-concrete joint section.3.Establish the local space finite element model of Jiangwan Bridge steel-concrete composite section with Midas FEA,study its mechanical behavior and force transfer mechanism,and verify the safety and rationality of Jiangwan Bridge steel-concrete composite section.In this thesis,the influence of the length of the steel lattice,the thickness of the bearing plate and the length of the joint section on the mechanical and transmission performance of the steel-concrete joint section was discussed by using the control variable method.which provides a reference for the construction and design of steel-concrete composite section.