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

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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