ABSTRACT
A laboratory-based test program was conducted to assess the performance of fillet welds in X-connections between Circular Hollow Sections (CHS). Six full-scale, fillet-welded CHS-to-CHS X-connections were designed to be weld-critical with varied key parameters that affect weld strength: branch-to-chord diameter ratio, chord wall slenderness, and branch inclination angle. By means of quasi-static tension applied to the ends of each branch, fracture of 12 test welds (two per connection) was obtained. Strain distributions adjacent to the weld and branch loads at rupture were measured. By using the carefully measured mechanical and geometrical properties of the fillet welds and CHS members, the structural reliability (or safety index) of the existing AWS specification provisions for weld effective lengths in CHS-to-CHS X-connections was determined. For the range of parameters studied, the existing AWS formulae were found to be very conservative, hence a comprehensive parametric modelling study is planned to develop more liberal recommendations.
