Assessment of American block shear load capacity predictions

Block shear is known to be a potential failure mode for several different types of connections. In this study,failure loads determined by experimental block shear tests performed in North America are compared with the corresponding capacities predicted by the current American Institute of Steel Construction Load and Resistance Factor Design and Allowable Stress Design Specifications. The two different design procedures are shown to provide a reasonable level of accuracy, although they both exhibit a fairly wide variation in experimental-to-predicted load capacity ratios. In an effort to identify and in turn, attempt to quantify the influence of additional connection parameters that may influence block shear behavior, several failure load design equations are developed to fit the experimental data. It is shown that (1) the variation in the capacity ratios can be significantly reduced by incorporating the 'aspect ratio' of the block and the in-plane load eccentricity measured to the bolt line, and (2) failure loads can be predicted with equal accuracy using either the material yield strength or the ultimate strength.