Study On The Behavior Of Steel-Concrete Composite Beams Under Combined Negative Bending Moment And Torque

When the axis curvature of the curve composite beam is large or the straight composite beams bear eccentric loads, it will generate complicated bending and torsion coupling effects. This paper is based on natural science foundation of Hebei Province Study on the behavior of steel-concrete composite beams under combined negative bending moment and torque(E2014210038). Experimental and theoretical studies are used for researching the bending and torsion effect of steel- concrete composite beams. The major works and conclusions are as follows:(1)Four straight composite beams is designed by setting different degrees of shear connection and initial torsion- bending ratio. Experimental researches are conducted under eccentric loads. The interfacial slip, ultimate bearing capacity, section strain, fracture spacing and fracture width are obtained through experimental research. The increase of degree of shear connection and the decrease of initial torsion- bending ratio will cause the increase of ultimate bearing capacity. There are both longitudinal slip and lateral slip appearing in composite beams. The crack spacing of concrete slab is greatly influenced by the transverse reinforcement.(2) The nonlinear stress analysis of the whole process is carried out by using the ANSYS software test beam. The calculation results of finite element and the experimental results are compared and verified. And further analysis of the composite beams in bending capacity are conducted.(3) By using the ANSYS software, the bending and twisting effect of the concrete composite beams after cracking are analyzed. The positive strain and the distortion of the cross section are the same as the normal strain before and after the concrete crack along the cross section. But the numerical value increased significantly after cracking. The diaphragm can significantly reduce the cross section distortion angle. Initial torsion- bending and degree of shear connection have a great impact rigid torsion angle(4)With Experimental results and ANSYS calculation results, the relationship between bending and twisting of the steel-concrete composite beams are analyzed. Torque has little effect on the ultimate negative moment of composite beams. But the negative bending moment has great influence on the ultimate torque...