In a RBS connection, the stress concentration is being prevented on the location of joint via local reduction of beam section near the column and the place of plastic hinge is being transferred from connection to a section of a beam near to the column. A special ilk of RBS connection which is named dogbone connection and its beam wings are cut from a circle in an arcuate form, has displayed a desirable performance against to the seismic loads. This paper aims at obtaining the best cutting geometry of the beam wing in order to improve the performance of the connection against to the seismic loads. For this purpose in this research, we have opted a several panel zone with different dimension on the beam wing under the influence of the seismic loads in Finite Element software called Abaqus along with a cyclic loading, modeled displacement control index and the best sample of cutting dimension among from the samples that are modeled.
