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RE: Application of 3Rw/8 - How to apply

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I'm still not clear on this one. You have stated pretty much what is written
in 2211.6 and the wording of this is what is confusing to me. I need a
practicle example. I would assume that you would first determine the
appropriate member size based upon applying the original load to the frame.
The 3Rw/8 term would be applied to the design of the beam to column
connection and therefore would be applied to the moment and shear at that
node. The initial load is not increased only the stress in the joint.
Is this a correct assumption?


-----Original Message-----
From: Horning, Dick/CVO [mailto:dhorning(--nospam--at)]
Sent: Wednesday, September 23, 1998 1:02 PM
To: 'seaint(--nospam--at)'
Subject: RE: Application of 3Rw/8 - How to apply

Rw = 6, not 8, for steel OMRF.  Framing elements not part of the lateral
force resisting system must be able to support gravity loads under a
displacement of 3Rw/8 times the calculated displacement of your moment
frame.  You don't need to multiply your moment frame forces by it.

> ----------
> From: 	Dennis S. Wish PE[SMTP:wish(--nospam--at)]
> Sent: 	Wednesday, September 23, 1998 12:38 PM
> To: 	SEA International List
> Subject: 	Application of 3Rw/8 - How to apply
> I design very little steel so I apologize up front for my lack of
> understanding regardless of the number of posts which have been sent on
> this issue. I am in need of a fast answer and would appreciate any
> responses.
> I have designed a simple (Ordinary) moment frame for a seismic retrofit.
> The frame is one bay - 25 feet between columns and 12 feet in height.  The
> lateral load applied from the results of the UCBC design is 10.57 Kips.
> The frame is pinned at the base and therefore develops moment in the
> connection of beam to column.
> Do I apply 3Rw/8 to the moment at the connection or is it applied to both
> the moment and the shear at the end of the beam?
> Also, is it correct to assume Rw is equal to 8 for use with an Ordinary
> Moment Frame?
> I appreciate any fast responses.
> thanks
> Dennis Wish PE