This paper presents an analytical model for the analysis of composite steel-concrete members accounting for partial interaction within the nonlinear finite deformation theory. Due to the complexity of the formulation the model is simplified within the framework of small strains and moderate rotations. This approach is considered acceptable for practical structural problems. The numerical solution is implemented by means of the finite element method. An application is presented to outline the use of the proposed formulation where the nonlinear problem is solved by means of an iterative procedure based on the Newton-Raphson method and implemented with a load-controlled incremental scheme. The proposed example consists of a cantilever subjected to an eccentric axial load. A larger deformability occurs due to the increments of bending moment in the deformed configuration when compared to the linear case.