Analysis For Thin-walled Box-section Beam Bridge In Bending And Torsional

Under a certain cross-sectional area under, the thin-walled box beam bridge can have a larger bending moment of inertia, and the torsional rigidity is particularly large; in the eccentric loads, the beam rib's force is more evenly, and the load-bearing structure combination of force transmission together the various components of the force, which achieve economic results and cross-section using a high efficiency. As the box-shaped cross-section of the structure has a good performance, so it has been widely used at a variety of bridges in the modern consequently. Therefore, study the mechanical properties of box-shaped beam bridge in-depth has a high practical value which under a variety of things external load.Based on thin-walled two-way bending and restrained torsion theory, this paper established box-shaped cross-section of the mechanical model of the beam bridge, and discarded the assumption of vertical warping displacement which include the elementary beam theory and the Umansky Theory, derived the expression of longitudinal warping displacement functions which based on linear interpolation function, derived the bending and torsion and second-order problem's Hamiltonian dual solving system of the box-shaped section which considered shear lag effect through the introduction of dual variables. Damit this solving system, use of boundary value problems at both ends of the precise integration method, programmed through the MATLAB language to solve the structure of generalized displacement and generalized force, anslysis of the vertical displacement and warping stress of box-section beam bridge in bending and torsion effects and second-order, through the solving of the example which compare with other methods', show the rationality and feasibility of this method, and has the main factors which affected the box-section beam bridge's vertical displacement and warping stress, as well as the cross-section dimensions and span in the same external conditions, the degree of influence on the vertical displacement, provide a reference for the box-shaped design of the bridge.This article provides a new analysis of box-section bridge theoretical method, the procedure for the preparation of forms for various sections of the bridge are applicable to. Can be resolved the displacement and force calculation problem under the beam bridge under the joint action of the vertical load and horizontal load and the torque, and can well reflect the actual force status of the box-section bridge. Application of the research results in this topic will have some guiding significance for the design of the project work.