Tearout Strength of Concentrically Loaded Bolted Connections

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 in concentrically loaded bolt groups 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. The results of this work increase understanding of the limit state of tearout and offer improved methods of evaluating this limit state in design.