Before the Northridge earthquake, the flexural frames with welded flange-bolted web connections were used in numerous steel structures as a ductile and appropriate earthquake resisting system. During the 1994 Northridge and the 1995 Kobe earthquakes, which occurred one year later, many moment frames were deteriorated in the beam to column joint region. After earthquake investigations showed that concentration of stress at the location of beam to column connection was the main reason for failure, and subsequently, some methods were offered to mitigate the problem. One of the proposed solutions was a reduction of beam section near the column, which shifts the stress concentration far from critical region. In this paper the nonlinear response of moment connection with a reduction in beam section, and with the box column sections has been studied, and the stress distribution near the column have been compared for both welded and Reduced Beam Section (RBS) moment connections. Studying the results, showed that the reduced beam section connections exhibit a desirable response in comparing with the common connections. RBS force the beams plastification away from the column face and avoids stress concentrations and large deformation in the column. Furthermore, in this research some recommendations on the appropriate geometric parameter such as the connecting gap from the column edge, the length of the reduced section of beam flange, and the depth of reduced section of beam flange are provided.