Effect of mid-connection detail on the behavior of x-bracing systems

In this paper, the effect of mid-connection detail of x-bracings comprised of build-up sections on the elastic–plastic behavior of braced systems is investigated. Then, a proposed symmetric mid-connection detail is compared with the commonly used one, analytically. In common mid-connection detail for build-up sections, one diagonal member (which is comprised of a pair of channels or angles) is usually discontinuous at the mid-connection and the other continuously passes through the connection. A rectangular gusset plate is used to join the discontinuous and continuous diagonals in practice. In the proposed method, one section from each diagonal member is discontinuous and the other is continuous. Buckling and post-buckling behavior of single span and single story models of cross-braced systems have been verified during a nonlinear static finite element analysis. The results show that the proposed mid-connection detail can improve both strength and ductility of cross-braced systems. Also, it is shown that adding two cover plates on both sides of discontinuous diagonal members in common mid-connection detail can partially improve the overall behavior of the system.