HSS Truss Connections: Q&A on Welding for the Hidden Toe Partial Overlap Condition
During the February 2014 SE University Session, Kim Olson discussed gapped and overlapped truss connections. She talked about the “Hidden Toe” partial overlap condition, and welding requirements for the hidden toe. Kim noted that welding of the hidden toe is not required if the components normal to the chord differ by 20% or less, and a question was posed by an attendee wanting to know what comparison should be made to evaluate the 20% difference.
Kim explained that the comparison is between the components of the branch forces normal to the chord member. This is also explained in two Modern Steel Construction articles linked below.
Overlapped connections were discussed in the “shop and field issues” column Special Treatment, written by Tom Schlafly, Director of Research at AISC, in the March 2008 issue of Modern Steel Construction (MSC). In the June 2010 issue of MSC, a question about whether the hidden toe should always be fully welded was posed as part of the Steel Quiz (see Question 4). In the answer, it states “[full] welding is only required if the normal components of the two branch forces differ by more than 20%.”
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