Tubular Web RBS Connection to Improve Seismic Behavior of Moment Resisting Steel Frames

A new type of Reduced Beam Section (RBS) connection called "Tubular Web RBS (TW-RBS)" is proposed in this research. TW-RBS is made by replacing a part of web with a tube at the expected location of the beam plastic hinge. In addition to analytical study, the proposed section is numerically studied under cyclic load using ABAQUS finite element software and a test specimen is used for calibration of numerical results. The results show that using TW-RBS not only creates a ductile fuse far from the beam-to-column connection components but it also increases story drift capacity up to 9%. Furthermore, the tubular web like corrugated sheet can improve both the out-of-plane stiffness of the beam longitudinal axis and the flange stability condition due to the smaller width to thickness ratio of the beam flange in the plastic hinge region. Thus, the tubular web improves lateral-torsional buckling stability of beam. On the other hand, the tubular web provides a better condition than other accordion web with sharp corners in terms of low-cycle fatigue, because change of direction of strain in arc shape of the tubular web section is smaller than the accordion web with sharp corners.