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RE: Ordinary moment connections - pre-engineered metal buildings

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The ICC IBC2003, Table 9.5.2.2 allows Steel OMF and IMF with endplate
connections for SDC D, E, and F per footnote "h" and allows OMF per footnote
"i" if the dead load of the roof is less than 15 psf.

-----Original Message-----
From: Haan, Scott M. [mailto:HaanSM(--nospam--at)ci.anchorage.ak.us]
Sent: Monday, April 05, 2004 3:06 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Ordinary moment connections - pre-engineered metal buildings


It is in the 97 UBC but it is not in the 2000 IBC or AISC Seismic.  I guess
many pre-engineered metal building manufacturers are designing OMRF
connections this way in Seismic Design Category D.

-----Original Message-----
From: Jim Persing [mailto:jpersing(--nospam--at)FHOARCH.COM] 
Sent: Monday, April 05, 2004 2:37 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: Ordinary moment connections - pre-engineered metal buildings


I think that the omega level forces come directly from the 97 UBC, Section
2213.6, para 2.
 
Jim Persing

-----Original Message-----
From: Carter, Charlie [mailto:carter(--nospam--at)aisc.org]
Sent: Monday, April 05, 2004 2:38 PM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Ordinary moment connections - pre-engineered metal buildings



AISC Design Guide 4 on end-plate moment connections is being typeset now. It
covers end-plates in SMF, primarily. I know of no basis for the assertion
that there is permission somewhere to design metal building OMFs for
omega-level forces and forget the member strength development requirements.
But I don't know everything, so I will check around and see what I can find.

 

Charlie

 

 


  _____  


From: Haan, Scott M. [mailto:HaanSM(--nospam--at)ci.anchorage.ak.us] 
Sent: Monday, April 05, 2004 4:11 PM
To: seaint(--nospam--at)seaint.org
Subject: Ordinary moment connections - pre-engineered metal buildings

 

Someone has indicated to me that the metal building industry is not
designing ordinary moment connections per the exact wording in AISC Seismic
section 11.2a.  I have not checked if this has been discussed on the list
before.

American Institute of Steel Construction [AISC] AISC Seismic Provisions
Section 11.2a indicates that fully restrained ordinary moment connections
need to be designed for a flexural strength Mu that is at least equal to
1.1*Ry*Mp of the beam or the maximum force that can be delivered to the
connection by the system or need to demonstrate an inelastic rotation of at
least .01 radians per AISC Seismic Appendix S and Section 9.2a.   The
special load combinations incorporating the over strength factor are meant
to approximate the maximum force that can be delivered to an element by the
system.  

It is come to my attention that it is the metal building industry standard
practice to design ordinary moment connections for the special load
combinations and not the options specifically written in the code: tested or
1.1*Ry*Mp or maximum load that can be delivered to the system.  The Metal
Building Manufacturer's Association [MBMA] in conjunction with the AISC are
in the process of drafting the "MBMA Seismic Design Guide for Metal
Buildings" which will allow ordinary moment connections to be designed for
the special load combinations.

Are other jurisdictions allowing special load combinations to design
ordinary moment connections as an approximation of the maximum load that can
be delivered to the connection by the system?

Why aren't the AISC Seismic Provisions written to allow the special load
combinations specifically for ordinary moment connections?  

Are the AISC Seismic Provisions going to be modified to specifically allow
this method of determining the internal forces for designing ordinary moment
connections?

  

 

Scott M. Haan P.E. 
Chief of Building Inspections 

Municipality of Anchorage 
Development Services  Department 
Mission Statement:  Guide safe construction and responsible development for
the community. 







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