Design of Single-Sided Fillet Welds under Transverse Load

Abstract

In North American steel design specifications, a directional strength-enhancement factor is used to increase the predicted strength of fillet welds subjected to transverse loading (i.e., loading at 90° to the weld axis). Committees have expressed concerns about this factor being unsafe for single-sided fillet welds; however, due to a lack of testing, only cautionary statements have been made in most specifications to address this. An experimental program was hence developed to test 40 transversely loaded single-sided fillet welds in cruciform connections subjected to branch axial tension. The connections varied weld size, branch-plate thickness, and loading eccentricity to investigate the effects of these parameters on fillet-weld strength. Results of this program are presented herein, and a first-order reliability method (FORM) analysis was performed. It is shown that current fillet-weld design provisions meet/exceed code-specified target safety indices (i.e., β=4.0) provided that (1) the directional strength-enhancement factor is not used, and (2) stresses that result in opening of the weld root notch are avoided.