Block Shear Strength of Coped Beam Connections with Double Bolt Lines

Abstract

Coped beam connections are commonly used in the construction of steel structures. Existing block shear provisions for these connections, with multiple bolt lines, account for the presence of uneven stress distribution only on the tension planes. This is inconsistent with the approach used to evaluate the strength of connections with only one bolt line, in which there is no consideration for the uneven stress distribution in the design equation. In this study, numerical finite-element models are developed, validated, and then used to evaluate the appropriateness of existing code provisions for predicting the strength of coped connections with two bolt lines. The numerical models can capture the full behavior of the connections up to and including complete fracture. The results show that the finite rotational stiffness of the connecting components is the primary cause of irregularity in the stress distribution, causing reduction in connection capacity. The results also show that the most significant shear lag occurs along the shear planes instead of the tension planes, which challenges the philosophy employed in major standards. The results demonstrate the inability of existing code equations to physically capture the behavior of the connection, which can inevitably lead to inconsistent predictions. The results are also used to propose a new design equation for predicting block shear strength in coped beam connections with multiple bolt lines. Additionally, a reliability analysis is conducted to determine the resistance factors of the proposed equations with consistent safety levels.