Suggesting double-web I-shaped columns for omitting continuity plates in a box-shaped column

Abstract

Generally the required strength and stiffness of an I-shaped beam to the box-shaped column connection is achieved if continuity plates are welded to the column flanges from all sides. However, welding the forth edge of a continuity plate to the column flange may not be easily done and is normally accompanied by remarkable difficulties. This study was aimed to propose an alternative for box columns with continuity plates to diminish such problems. For this purpose a double-web I-shaped column was proposed. In this case the strength and rotational stiffness of the connection was provided by nearing the column webs to each other. Finite element studies on about 120 beam-column connections showed that the optimum proportion of the distance between two column webs and the width of the column flange (parameter <TEX>${\beta}$</TEX>) was a function of the ratio of the beam flange width to the column flange width (parameter <TEX>${\alpha}$</TEX>). Hence, based on the finite element results, an equation was proposed to estimate the optimum value of parameter <TEX>${\beta}$</TEX> in terms of parameter <TEX>${\alpha}$</TEX> to achieve the highest connection performance. Results also showed that the strength and ductility of post-Northridge connections of such columns are in average 12.5 % and 54% respectively higher than those of box-shaped columns with ordinary continuity plates. Therefore, a double-web I-shaped column of optimum arrangement might be a proper replacement for a box column with continuity plates when beams are rigidly attached to it.