To study the interface slip and the deflection properties of a new type of steel-encased concrete composite beams, four full size simply supported specimens with different shear connection coefficient were designed. One was a beam with full shear connection, and the others with partial shear connection. According to the experiment , a set of load-slip curves and load-deflection curves are derived. Based on these results, the interface slip development process and distribution laws are gained. Taking the interface slip into account, a nonlinear finite element analysis model is established by using the finite element analysis soft-ANSYS, and gains a reasonable shearing connection coefficient. Based on the actual code, a theoretical formula is proposed for deflection. The results of finite element model and theoretical formula are proved to be in good agreement with the experimental data.
