Experimental Evaluation of Design Procedures for Fillet Welds to Hollow Structural Sections

This paper discusses contemporary design procedures for fillet welds to hollow structural sections (HSS) in several prominent design codes. The structural reliability associated with the directional strength-enhancement factor contained in North American Specifications is examined, based on a set of laboratory tests on fillet-welded connections between HSS and rigid end-plates. A total of 33 connections, in which the welds had been designed to be the critical elements, were tested to failure by axial tension loading applied to the HSS members. The experimentally obtained weld strengths were compared to the predicted nominal strengths. The directional strength-enhancement factor was found to lead to unsafe strength predictions, particularly for large weld sizes. Hence, a restriction on the use of this factor for fillet welds to HSS members, in North American steel design specifications, needs to be considered. The analysis also shows that Eurocode 3 fillet weld design provisions give conservative strength predictions.