Steel Moment Frame connections

[EBF]

I was wondering if anyone had any information on recent testing that may have been done using TS or pipe columns with moment frames. I am working on a moment frame building and the architect would like to use pipe or tube columns. According to Fema 350 all moment frame connections be prequalified, and only WF columns were tested, so is that our only choice?

 

[Taro]

Within the SAC/FEMA program, only a limited range of wide flange columns have been tested to qualify as special moment frames (SMRF). If you want to use tube or pipe sections, you can either do project-specific testing to qualify the connections as SMRF ($$$) or design it as an ordinary moment frame.

 

[EBF]

So it is ok to use pipe or TS columns for OMF? Is there any special detailing for these connections? What I know of Fema 350 doesn't address this issue...

 

[shemp]

Because you are looking at FEMA 350, I assume you must be in a high seismic area with a seismic design category of D or above. If you are, then it is my understanding that you are not allowed to use an ordinary moment frame. The supplement to the IBC modified Table 1617.6 so that OMF's are "not permitted" in SDC D, E, or F. In SDC D, you would be allowed to use an Intermediate Moment Frame as long as the height of your building doesn't exceed 35 feet.

 

[JAE]

shemp -

Are you talking about steel or concrete? What supplement are you talking about? Can you provide a link on the ICC website to show what supplement you are referring to? Thanks

 

[shemp]

I should have been more specific. I don't have the 2003 IBC, so I was referring to the 2000 IBC and the 2002 Accumulative Supplement.

Here's the link in case you're interested, but considering it's outdated, you're probably not interested!

http://www.iccsafe.org/dyn/prod/3001SP02.html

Also, I was referring to steel.
Does the 2003 IBC prohibit the use of steel OMF's in SDC D?

 

[EBF]

I am not familiar with the IBC, I am using the 2001 California Building Code, which as far as I know doesn't prohibit the use of steel OMF in Seismic Zone 4, though there is a height limit. If this is incorrect, please let me know and provide a reference...

 

[JAE]

I don't believe that the original IBC 2000 prohibited the use of OMF's and I guess the issue here would be if the city or governing agency required the 2002 Supplement, which most cities do not do. But apparently the revisions to the IBC have done something to limit its use.

 

[EBF]

I looked in the 2002 AISC Seismic Provisions, and they mention the new limitations on the use of OMFs and they refer to FEMA 2000g...

 

[ERV]

EBF,

California Building Code (2001) is based on the 97 UBC, which is much less restrictive than any of the newer codes. Stick to California Code of Regulations, Title 24, Volume 2, Chapter 22, Division I thru XI for structural steel and Chapter 22A Division I thru XII for cold formed steel. Seismic Provisions are covered in Section 2210. California still uses clasifications of Seismic Zones 1 thru 4, much simpler than other codes. For seismic zones 3 & 4 OMF's, SMF's, CBF's and EBF's are permited. K-bracing is not permited.

If you have the 2001 California Building Code, you should read it carefully. See the section I have referenced above, Page 2-248 in my book (loose leaf edition). I don't think that you will have a problem with your design as long as the connections conform to the code.

 

[seismiczone]

Non-qualified connections as per FEMA 350 can be used in seismic zone 4 with CBC 2001 (UBC97) if they are designed with an R value = 1.0

 

[kalico]

Where is FEMA 350 does it allow the use of non-qualified connections designed with an R of 1? Is this a requirement specific to the california code?

 

[seismiczone]

That's great Kalico. I tend to write in a criptic way for these responses. Actually, non-qualified connections can be used with an R value of 1 as per an administrative bulletin for San Diego County. It is not in FEMA 350.