Shear Lag Effects in Tension Members with Short Longitudinal Welds

Abstract

Shear lag can reduce the strength of tension members and must be considered when calculating tensile rupture strength—for example, by using the shear lag factor. The shear lag factor defined in Case 4 of AISC Specification Table D3.1 (2022) applies to tension members where the load is transmitted by longitudinal welds only. This shear lag factor was developed through analysis of physical experiments, but predominantly with experiments on specimens that failed by weld rupture, potentially leading to unnecessarily low values of the shear lag factor. As a result, the behavior of tension members with short longitudinal welds, for which the shear lag factor can be much less than unity, is uncertain. In this work, previously published experiments are reevaluated, and new experiments are reported. The results shed light on the behavior of tension members with short longitudinal welds. Despite current design provisions indicating that tensile rupture is an important limit state for tension members with short welds, no evidence that tensile rupture or shear lag influences strength of such members was identified. For plate tension members, use of a shear lag factor of U = 1 was found to be acceptable because other applicable limits states that better represent the physical behavior control. These results show the need for further research to better characterize the behavior of welded tension members and to simplify design provisions.