Overstrength of I-Shaped Shear Links for EBF Design

Past experimental research on EBF indicated that the link overstrength, particularly that for short (i.e., shear) links, could be much higher than that specified in the AISC Seismic Provisions, thus potentially leading to an unsafe design of beams, columns, and gusset connections per the capacity design requirements. This study aims to identify key factors contributing to the high overstrength and to derive an expression to predict the overstrength of short links. Available experimental data were first collected, and main parameters affecting the overstrength were identified from the database and used for a multi-variate regression analysis. It was found that the following two parameters affect the link overstrength the most: (1) the Fu/Fy ratio between the actual tensile strength and yield stress and (2) Kw, a factor that represents the contribution of localized bending of link flanges. The link length, to a lesser extent, also affects the overstrength. A predictive overstrength equation based on these three parameters was proposed for capacity design of EBF with short links.