Bending characteristics of composite box girder considering all surfaces shear deformation based on Hamiltonian system

The composite box girder does not satisfy the assumption of flat section in the actual force behavior. The transverse force generated by the bending is transmitted to the shear key through the web, and then transmitted to the wing plate by the shear key. The shear deformation of the channel steel box girder web makes the shear stress of the composite box girder section unevenly distributed on the wing plate. The selection of displacement function caused by shear deformation is often unclear in physical meaning, and analysis and verification that conform to the actual deformation and stress distribution law of the structure are rarely carried out. Aiming at this problem, a microplate shear flow analysis method is proposed. Considering the influence of shear deformation, the shear lag warping displacement function of the composite beam is derived, and the displacement function is corrected according to the self-balance condition of the warping normal stress, which makes up for the defect of the unclear physical meaning of the displacement function. On the problem of solving the control differential equations. For the first time, it is proposed to use Hamiltonian theory to solve the problem, which avoids the problem of solving high-order differential equations in the classical elasticity solving method and the functional variational method based on the energy principle. The stress distribution of the composite box girder under the action of concentrated load and uniform load is analyzed.