Structural behaviour of bolted moment connections in cold-formed steel beam-column sub-frames

This paper presents an experimental investigation on bolted moment connections between cold-formed steel sections. A total of 20 column base connection tests and beam-column sub-frame tests with different connection configurations were carried out to assess the strength and stiffness of bolted moment connections between cold-formed steel sections. Among the tests, four different modes of failure were identified: • Mode BFcsw: Bearing failure in section web around bolt hole • Mode LTBgp: Lateral torsional buckling of gusset plate • Mode FFgp: Flexural failure of gusset plate • Mode FFcs: Flexural failure of connected cold-formed steel section For those connections failed in Mode BFcsw, the moment resistances of the connections were typically found to be below 50% of the moment capacities of the connected sections. For those connections failed in Modes LTBgp and FFgp, the moment resistances of the connections were found to be about 60% and 75% of the moment capacities of the connected sections. Among all, the moment resistances of those connections failed in Mode FFcs were the highest with a minimum of 85% of the moment capacities of the connected sections. Consequently, it is demonstrated that through rational design and construction, effective moment connections between cold-formed steel sections may be readily achieved. Engineers are encouraged to build light-weight low to medium rise moment frames with cold-formed steel sections.