Welding of bar joist seats to steel beam flanges

[Brewdude]

An interesting question was raised today when looking at an RFP for a project. In this project, originally 3/16" welds, 3" long, were specified for the purpose of welding bar joists to a beam flange based on minimum requirements of the AISC code. However, many bar joists that are used today have seats which are less than 3/16" thick and thus only use a 1/8" weld. In this RFI they would like to use 1/8" welds at 4 1/2" long, which makes sense to me, however doesn't satisfy the AISC minimum weld thickness requirements. How does SJI justify this weld being okay?

 

[gtaw]

I thought open web members were welded per the requirements of the Steel Joist Institute.

Their requirements are considerably less stringent that either AISC or AWS.

If the joists are not joist girders, the weld is simply to keep the joists from being inadvertently displaced. The weld length is much less than 3 or 4 inches.

Best regards - Al