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 an analytical study, the proposed section is numerically studied under cyclic load using ABAQUS finiteelement software, and a test specimen is used for the calibration of numerical results. The results show that using TW-RBS not only creates a ductile fuse far from the beamto- 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.