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Abstract

The limit state of tearout can complicate the design of steel bolted connections since, in contrast to the limit states of bearing and bolt shear rupture, tearout strength can vary from bolt to bolt within a connection. Under the current AISC Specification, tearout strength is proportional to the clear distance, in the direction of force, between the edge of the hole and the edge of the adjacent hole or edge of the material. However, recent studies on concentrically loaded bolt groups have suggested that the use of clear distance may not accurately represent tearout strength and have proposed alternative lengths for use in strength equations. A reevaluation of the limit state of tearout is presented in this work, including a thorough evaluation of the proposed alternative tearout lengths using a large database of previously published experimental work and new experiments with various edge distances and hole types. Equations with the alternative tearout lengths were found to be more accurate than those with clear distance, especially for small edge distances. Design recommendations including the alternative tearout lengths were developed. A reliability study on the existing provisions and recommended provisions was also completed to ensure the safety of these recommendations. An alternative design approach in which the limit state of tearout is captured implicitly through reduction factors applied to the bearing and shear rupture strength was also developed. Additionally, the impact of tearout on the behavior and design of single-plate shear connections, one of the most common applications of eccentrically-loaded bolted groups, was investigated with the goal of determining if the simplified approach for considering tearout recommended in the AISC Manual for conventional connections is appropriate and how best to consider tearout for extended connections. Experimental testing of beam and column subassemblies with single-plate shear connections showed that small horizontal edge distances do not necessarily decrease the strength of the connection. The results of this work increase understanding of the limit state of tearout and offer improved methods of evaluating this limit state in design.