DSM for ultimate strength of bolted moment-connections between cold-formed steel channel members

Experimental tests have previously shown that the strength of bolted moment-connections between cold-formed steel channel members, where the connections are formed through an array of bolts in the web, is dependent on the length of the bolt-group. This reduced strength has been observed in tests on portal frame joints as well as overlapped purlin joints. For a long bolt-group length, an upper bound would be the full in-plane major axis moment-capacity of the section, which can be predicted using the conventional Direct Strength Method (DSM). For a short bolt-group length, in the order of the depth of the section, a reasonable lower bound to the reduced strength can be predicted by using the DSM, modified to include the effect of the bimoment at the connection. In this paper, a parametric study is performed covering sections of different values of slenderness.