A finite element model for composite beams with interlayer slip

A new element finite model of composite beams is presented in this paper, which is applicable for analysis of steel frames. The equilibrium differential equation of composite beam with interlayer slip is established on the basis of Newmark's one-dimensional partial interaction theory. With the combination of the characters of composite girders and by introducing the rational boundary conditions, the elastic stiffness function of composite beam element is deduced, which can consider the influence of the slip between interfaces. The composite beam element presented in this paper has the less nodal degree of freedom. And only one element is needed for a component, which makes the analysis of frame structure more efficiently. The study of this paper also provides the theoretical basis for establishing the elastic-plastic element stiffness matrixes of composite beams, which can consider the nonlinear factors such as crack and crush of concrete and yield of steel.