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RE: Design Moment For Semi-Rigid Connections - rules to get a per mit

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Some rules to getting permits for partially restrained connection moment
frame structures:

Rule 1: The building official is always right.
Rule 2: In case the building official is wrong refer to rule number 1.



Scott M Haan P.E.
Plan Review Engineer
Building Safety Division http://www.muni.org/building
Development Services Department
Municipality of Anchorage
phone:907-343-8183  fax:907-249-7399
mailto:haansm(--nospam--at)ci.anchorage.ak.us



-----Original Message-----
From: Peter Higgins [mailto:76573.2107(--nospam--at)compuserve.com]
Sent: Wednesday, April 25, 2001 7:35 PM
To: INTERNET:seaint(--nospam--at)seaint.org
Subject: RE: Design Moment For Semi-Rigid Connections - see AISC Seismic
P rovisions for OMF


Message text written by INTERNET:seaint(--nospam--at)seaint.org
> 
Peter can tell you how to do a wind-frame analysis.
 <

There's an easy cheat:
1) Design the beams as simply supported (i.e. no help from the end
connections-you can't go wrong there)
2) Design the connections for the lateral load moments only, using the
Omega's, etc. as required.
3) Ensure reasonable ductility. This is the trick. You MUST know the
rotational behavior of the connection in both the semi elastic and post
semi elastic range. This almost always requires testing. However, Chen and
a bunch of other guys are trying to develop analytical models which will
allow decent designs without testing. However, I consider it a work in
progress, at least for buildings. Storage racks are required to test their
connections to failure, generating the information needed, which is the
basis of how I do the designs Scott has such an aversion to. [I think he
has an allergy to my seal actually]

This sounds heretical, but it actually brackets the upper bounds for each
component.

And yes, it does have a very solid theoretical foundation. I'll provide you
references if desired. They're all very old as this was a favored design
method in the pre computer days.

Good Luck, but be very careful of item 3.

Regards,

Peter Higgins

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