Theoretical Research On Torsion And Flexural-Torsional Buckling Of Rectangular Honeycomb Beams With Concrete Filled Steel Tubular Flanges

Rectangular honeycomb beams with concrete filled steel tubular flanges not only has the characteristics of high strength,high stiffness,high stability and high bearing capacity of I-shaped beam with concrete-filled steel tube flanges,but also has the characteristics of honeycomb beams such as aesthetics,economy and space utilization.In order to make rectangular honeycomb beams with concrete filled steel tubular flanges widely used in practical engineering,on the basis of professor Zhang Wenfu's "the Plate-Beam Theory" and combined with the continuous model idea to deal with the web opening problem,the torsion buckling and flexural-torsional buckling of rectangular honeycomb beams with uniaxial symmetric and biaxial symmetric concrete-filled steel tube flanges are theoretically analyzed and studied in this paper.The correctness of theoretical derivation is verified by the modeling analysis of finite element software ANSYS.The main contents of this paper are as follows:(1)Based on the "the Plate-Beam Theory" and the idea of continuum model,the torsion of rectangular honeycomb beams with with uniaxial symmetric and biaxial symmetric concrete-filled steel tube flanges is theoretically analyzed and studied.The formulas for calculating the total strain energy,free torsional stiffness and restrained torsional stiffness under torsional buckling are given.Furthermore,the energy variational model,differential equation model and three common boundary conditions are established.(2)By using the equilibrium equation of rectangular honeycomb beams with concrete filled steel tube flanges bearing concentrated torsion only at the free end,the calculation formula of torsion angle at the free end is given.The static analysis model is established by using finite element software ANSYS,which verifies the correctness of the theoretical deduction of torsion and the formula for calculating the torsion angle of free end.(3)Based on the "the Plate-Beam Theory" and the idea of continuum model,the bending-torsional buckling of rectangular honeycomb beams with uniaxial symmetric and biaxial symmetric concrete-filled steel tube flanges is theoretically analyzed and studied.The formulas for calculating total strain energy,total initial stress potential energy,total potential energy and bending stiffness under flexural-torsional buckling are given.Furthermore,the energy variational model,differential equation model and three common boundary conditions are established.(4)Based on the total potential energy of flexural-torsional buckling,the equilibrium equation of flexural-torsional buckling of simply supported rectangular honeycomb beams with concrete filled steel tube flanges under pure bending is given,analyzed and solved.The calculation formula of critical load under flexural-torsional buckling is given.The finite element software ANSYS is used to establish the model.The static analysis and modal analysis are carried out to verify the correctness of the theoretical derivation and the formula for calculating the critical load of simply supported beam under pure bending.