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RE: R-values in Seismic Provisions

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Dick,

A few caveats are in order on this topic.  

Caveat 1:
Ron Hamburger is correct and is intimately familiar with the R values.  That R value war is currently under way and I would categorize Ron as the General Pershing in that war.  I am just a lowly guy in a trench trying not to get hit by a stray bullet.

Caveat 2:
The 1996 Blue Book and the 1994 UBC used Rw values not R values.  They are different. The 1997 UBC, 1998 NEHRP, and the 2000 IBC all use the R values.

The point I was making in my original post, was that I did not understand the source of the inordinately low R values, and that the low R values implied an elastic response.

Harold Sprague, PE
Krawinkler, Luth & Assoc.


-----Original Message-----
From:	Horning, Dick/CVO [SMTP:dhorning(--nospam--at)CH2M.com]
Sent:	Tuesday, September 15, 1998 9:24 AM
To:	'seaint(--nospam--at)seaint.org'
Subject:	RE: R-values in Seismic Provisions 

I think those speakers are misinformed, or don't understand the rationale
underlying the R factor.  For background, see the 1996 Blue Book, Page
119-120.

> ----------
> From: 	Bill Sherman[SMTP:SHERMANWC(--nospam--at)cdm.com]
> Sent: 	Monday, September 14, 1998 4:53 PM
> To: 	seaint(--nospam--at)seaint.org
> Subject: 	R-values in Seismic Provisions 
> 
> Harold Sprague wrote: 
>  
> > An R of 1 would imply an elastic response. < 
>  
> While I would agree with the above statement, I have heard some speakers
> on 
> seismic design state that an R-value of approximately 2.0 under the 1997
> UBC 
> would relate to a "fully elastic response".  This does not make sense to
> me
> - 
> can anyone explain the basis for this statement? 
>  
>  
> 
> 
> 
> 

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