Numerical Evaluation of New Reduced Beam Section Moment Connection

Reduced beam section (RBS) moment resisting connections are among the most economical and practical rigid steel connections for high rise buildings that developed after the 1994 Northridge, earthquake. Section weakening concept in the plastic hinge region of beam cause to reduction of beam plastic section modulus in this region, and force plastic hinge to occur within the reduced section. In the ordinary RBS connection mostly portions of the beam flanges are selectively trimmed in the region adjacent to the beam-to-column connection that causes the plastic hinge to form in weakening section. This paper presents a new RBS connection that has been used aforesaid weakening concept in it, with this difference that corrugated plate webs instead of beam flange cutting were used in limited specific length near the column face. Corrugated plates because of their accordion effect don't have bending rigidity. Then using of these plates in plastic hinge region reduces the beam plastic section modulus and plastic hinge is formed in corrugated region. For investigating the seismic behavior and performance of new RBS moment connection, finite element analyses were executed. All of the analytical results of new RBS connection were compared with ordinary RBS connection results. This comparison shows that the corrugated webs will improve the plastic stability and provide capability of large plastic rotation at the plastic hinge location without any appreciable buckling and brittle fractures in this region. Comparison of the seismic performance of new RBS connection with ordinary reduced beam section connection (dogbone connection) led to the conclusion that new RBS connection allows for the most stable motonic response at large story drift levels.