Convergent braces are usually used for stability of frames against lateral forces in seismic design. According to the seismic design philosophy, it's expected that convergent bracing systems could show a non-elastic and steady response under intense earthquakes. In such frames, braces are connected to beams and columns by a plate and non-elastic deformation occurs at the time of yield of the member by tensile and non-elastic buckling. The new experimental tests show that the seismic performance of convergent braces improves by connection plate design and permitting connection plate to yielding. In this research, the connection plate effects and its changes and also the inelastic finite element model and analysis methods are investigated and compared with experimental results. Important details in frames connection are including the effect of brace plate in rigidity of the column-beam connection, shape and thickness of connection plate and analysis of non-elastic deformations. The proposed results will lead to improve the shape and details of this type of connections.