Evaluation of the recent IIW (2012) and ISO (2013) strength equations for axially loaded CHS K gap joints

Over the last decade, extensive numerical analyses have been conducted on axially loaded uniplanar K gap, T and X joints made of circular hollow sections (CHS), considering a wide range of geometrical parameters and different types of chord load. Based on the large amount of numerical data, in 2007, new joint capacity and chord stress equations were derived for CHS joints. This article presents detailed comparisons made between the (mean) strength equations for K gap joints and the experimental data available. These design equations were first discussed and approved by Sub-commission XV-E of the International Institute of Welding (IIW), subsequently published in the CIDECT Design Guide for CHS joints [1] and adopted in the 3rd edition of the IIW Static Design Procedure for Welded Hollow Section Joints [2], which formed the basis for the ISO 14346 recommendations [3] published recently.