Bracing requirements and design for a single column considering semi-rigid connections and initial curvature

The use of bracing has been widely recognized as an effective technique to increase the strength of columns by reducing their effective length. This paper presents an assessment of the bracing requirements for a semi-rigidly connected column, which is laterally braced at the mid-height. By utilizing the proposed half-length column model, the effects of column stiffness and initial curvature on the brace strength and stiffness requirements are investigated. The results indicate that the column's initial curvature coefficient increases with a higher applied load, but decreases with increased column end connection stiffness. The required brace stiffness requirement stipulated in AISC 360-22 should be increased when considering the effect of column's initial curvature. Following the design concepts of AISC 360-22 and CSA S16-19, equations for assessing the bracing requirements for a semi-rigidly connected column are proposed. These equations are validated against the finite element analysis results, demonstrating their ability to accurately assess the bracing requirements for semi-rigidly connected columns. These equations can be adopted in current engineering practice.