Block Shear Equations Revisited...Again

Abstract

Shortly after block shear was first identified as a possible failure mode for coped beam connections, design equations to account for it were incorporated into ASD provisions. These equations never changed, partly due to ASD not being updated since 1989. However, LRFD treatment of block shear changed with each new Specification. Over the years, it was suggested that the effect of eccentricity was missing from block shear equations. On the surface it appears that the effect of eccentricity on the block shear strength of connections, as suggested by previous investigators, has now been incorporated into the latest unified Specification. For many connections, however, nothing has changed. It is the conclusion of this paper that additional important cases need to be shown in Commentary Figure C-J4.2 of the 2005 AISC Specification for which block shear equations now incorporate a new factor to account for connection eccentricity. In particular, as a minimum, angles connected by only one leg or tees connected by their flanges should also be included with other connections for which block shear capacities are now reduced.