I am analyzing an existing "moment" frame that penetrates a wood roof structure to an equipment platform above and the designer used HSS columns and W shape beams. He shows a bolted moment connewction of the W shape to the HSS column.

Are there any pre-qualified bolted connections for this type of connection? It was done in 2005 under the 2003 IBC. A325-N bolts. The designer used 1" plate on the beam side thru-bolted through the HSS with no backing plate and it has me concerned as to the pull through aspect of the tensioned bolt thru the HSS section.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

Supplement 1 for AISC 358-10 has a pre-qualified HSS column moment connection. Not sure if it was in use back then though....

http://www.conxtech.com/

The only comment I have seen is in the Seismic Design Manual where it states in C.2.3.2b, in the middle of page 6.2-51, that the nelastic effects must be restricted to the beam to prequalify the connection - kinda nebulous to me as no specific type of connection is mentioned, bolted or welded.

I also checked the HSS and the section used, an HSS6X6X.5 does satisfy local buckling requirements (Table 1-4b).

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

Appendix P of AISC 341-05 contains the pre-qualification requirements. Then appendix S gives the testing requirements.

In the post-Northridge worlds, I saw a company use the stringent (i.e. SMF) detailing provisions, but with a reduced R = 3.0. That was just so that the buidling official would let them use a non-prequalified connection for their project. That was in the 1997 UBC days when no one really knew what to use for their moment connections....

The conx connection is proprietary. It was probably not the connection you are dealing with. Is this intended to be a seismic condition? Please provide a sketch. I am assuming a plate welded to the HSS wall, flare bevel at the sides and fillets top and bottom. Several issues with this in a seismic application. But it can be analyzed for non-seismic application. I am not sure of an design example. I usually us paddle plates for moment connections to HSS columns. Or provide stiffeners for direct welding of the beam.

www.FerrellEngineering.com

This is in a high seismic region, so the answer is a very big YES.

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com

The Conxtech connection is the only prequalified connection with HSS column. This is a proprietary connection and was not qualified in 2005.

www.FerrellEngineering.com