Research And Application Of Flame Straightening On Welding Deformation Of Web Plate In Steel Box Member In Bridges

As one kind of basic structure components of steel bridge, box members are widely used in truss beam bridge, truss arch bridge, stiffening girder of cable-stayed bridge and suspension bridge. All this time, the welding deformation in the process of manufacturing has been an impact to the production efficiency and quality of these members. In this thesis, web plate in steel box member was taken as studied object based on thermal elastic-plastic FEM with the help of ANSYS and flame straightening process on one-dimensional transverse bending deformation in web of box members was simulated.In this thesis, the main work contains:First of all, it introduces the fundamental theory of flame straightening on welding residual deformation. And it is targeted to discuss the applications and characteristics of finite element analysis theory in the flame straightening. The basic forms of heat transfer in the process of flame straightening and the basic equations of FEM thermal analysis have been put forward. Also the discrete methods to solve the nonlinear transient problems are further elaborated. Then it briefly illustrates the fundamental theory of the finite element analysis of deformation field in flame straightening and summarizes the basis as well as solution method of thermal elastic-plastic FEM theory.Secondly, simulation steps of the temperature field are summarized in detail as well as the deformation field. Then elaborates and solves the key problems such as:how to establish and divide the model, which kind of unit and model of the heat source should be chosen, how to select appropriate heat source parameters, how to apply the boundary conditions and the load, how to make heat source move, even how to achieve the coupling between the temperature field and deformation field.Thirdly, commences thermal analysis and mechanical analysis respectively based on the established calculation model. Then research the spread and change of temperature and deformation during process of flame straightening as well as cooling and discusses mechanism and operation rule of Welding deformation flame straightening.Finally, analyzes influence on flame straightening process by factors in aspects of both parameters and process. Then optimizes parameters and measures of flame straightening on one-dimensional transverse bending deformation of web plate in box member. The results of the calculation are checked by the experimental data to verify the reliability of the calculated value. It provides important reference for optimizing process as well as improving efficiency of flame straightening.Based on the method described in this thesis, flame straightening on welding deformation of web plate in steel box member was simulated effectively. Through comparison analysis with experimental data, results of the calculation proved to be correspond to reality. Application of the research method in this thesis can be extend to flame straightening on not only entire box member but also other members in steel bridges. The proposed optimizations are of positive significance.