Abstract: According to the experimental and numerical results for RC column-to-steel beam (RCS) connections, the P-M model, which can predict the shear strength versus the shear distortion response of RCS connections, is modified and a design model taking account of both the bearing deformation and shear distortion in the inner concrete is presented. The model is based on the fact that the RCS joint deformation is three-dimensional. The inner and outer concrete should be separated and each of them is assumed to be in the state of plane strain, respectively. The deformation of inner concrete is larger than that of outer concrete. Besides a shear distortion, a large bearing deformation exists in the inner concrete. The nominal strength formulae and design equations for exterior RCS joints are obtained based on the modified model and numerical results. The shear strength of the joint at 2.0% total joint deformation is taken as nominal strength. These formulae can be used as a reference for drafting the Code.