In this study, first, one RC frame and one RC frame retrofitted by steel braced frame utilizing a hybrid connection technique related to an experimental investigation, were modeled and analyzed through non-linear static analysis method in OpenSees software. The hybrid connection provides the connection between the RC frame and the steel brace frame. For evaluation of the accuracy of modeling, the hysteresis diagrams related to displacement of the non-retrofitted RC frame and retrofitted one were obtained. The comparison between the hysteresis diagrams of the experimental result and the hysteresis diagrams obtained from non-linear static analysis demonstrates the accuracy of the bare and retrofitted RC frames modeling in OpenSees software. In the second part of this research, one existing soft-first-story building related to an analytical investigation, was modeled in OpenSees. Then the building was assumed to retrofit by steel braced frames utilizing a hybrid connection technique and a strategy for retrofitting the existing building was planned. Therefore, retrofitted building by this strategy was modeled and analyzed through nonlinear static and incremental dynamic analyses (IDA) in OpenSees. Finally the obtained results related to the soft-first-story building and retrofitted one were compared. The comparison between collected results related to the soft-first-story building and the retrofitted one, demonstrates the effectiveness of retrofitted building for the increase of strength, stiffness and ductility.