RE: Steel SMRF beam connection

I am considering a similar situation right now. One end of a single bay, one story frame does not have room for the same size column because it is between a repetitive window system. All that will fit on one end is a 6x6 tube or wide flange column. A 24" WF column will fit in the other end. I can't meet the drift requirements unless the base of the 24" column is fixed. (I am using OMF) If I do this, is it now a cantilever column even though there is a moment connection at the top of the 24" column to the beam? And if so then we have the R in one direction conundrum. We are squeezing this in under the 98 Calif Building Code.

 

Jeff

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From: Shaun Dustin [mailto:sdustin@cc.usu.edu]
Sent: Saturday, November 24, 2007 9:34 PM
To: seaint@seaint.org
Subject: RE: Steel SMRF beam connection

Oscar,

 

We used to do this when I was designing a lot of SMFs, but only as an extension on a multi-bay line of frames—never as a one-sided half bay frame.  I’ve analyzed a lot of those multi-bay with a half-bay on the end, and I can tell you you get very little (if any) capacity out of such a frame. The only reason I would ever leave them in a design is if I had a cantilever where I was using a full bay as the backspan or if I needed a little nudge to make redundancy work under CBC.

 

Shaun Dustin, MS, PE

Doctoral Candidate

USTAR Biofuels Initiative

Utah State University
4130 Old Main Hill
Logan, UT 84322

sdustin@cc.usu.edu

435-770-7816

 

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From: OSCAR HENRIQUEZ [mailto:OHENRIQUEZ@ms-ae.com]
Sent: Wednesday, November 21, 2007 5:46 PM
To: seaint@seaint.org
Subject: Steel SMRF beam connection

 

 

Can someone tell me if it is allowed, as part of a steel Special Moment Resisting Frame (SMRF) system, to have a beam with a pre-qualified RBS moment connection at one end of the beam and a simple shear connection at the other end of the beam?  Without getting into details of why we are doing this, I would like to know if having such connections will disqualify the frame from being a SMRF.  If this is not allowed, where is this stated in the CBC or Specifications?

 

Happy Thanksgiving everyone!

 

 

Oscar Henriquez, P.E.

McLean & Schultz

Brea, CA 92801