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RE: AWWA D100

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I'm talking about RF per D100 Section 13.4.  My response spectra has a
475 year return period versus 10,000 for RF = 2.5.
D100-96 is still the primary code used in the industry until the new one
is published.
Thanks-
Al

> -----Original Message-----
> From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com]
> Sent: Tuesday, December 21, 2004 2:22 PM
> To: seaint(--nospam--at)seaint.org
> Subject: RE: AWWA D100
> 
> 
> Albert,
> 
> In response to your particular question, the answer is no.
> 
> You really have me confused.  If you are looking at the D 
> 100-96, the "force 
> reduction factor" is Rw (not Rf) which is really a response 
> factor and is 
> independent of the ground shaking / seismicity.
> 
> It sounds like you are trying to fine tune a tank design.  If 
> so the "out of 
> the can" D 100-96 is not the proper tool.  Besides, it is the 
> Z that defines 
> seismicity (recurrence periods) and the ground shaking.  All 
> that aside, the 
> rest of the seismic code world left much of the D 100-96 
> behind several 
> years ago without MAJOR tweaking.
> 
> To get what I think you want, use the ASCE 7-02, Section 
> 9.14.7.3.  If you 
> want to modify the seismic probabilities, do it within the 
> SDS and SD1 
> calculations.  Don't modify the R.  You will probably want a 
> site specific 
> response spectra developed for the probability that you desire.
> 
> I would also suggest that you read the FEMA 450-1 and FEMA 
> 450-2, Chapter 14 
> for the commentary that led to the development of the tank provisions 
> contained in ASCE 7-02.  You will find similar changes in the 
> ACI 350.3.
> 
> BTW, the D 100 is in the process of a major upgrade.  I 
> believe that it is 
> being balloted now.  Seismic is one of the MAJOR overhaul areas.
> 
> Regards,
> Harold Sprague
> 
> 
> 
> 
> >From: "Al Grathwol" <AGrathwol(--nospam--at)BoyleEngineering.com>
> >Reply-To: <seaint(--nospam--at)seaint.org>
> >To: "SEAOC List (E-mail)" <seaint(--nospam--at)seaint.org>
> >Subject: AWWA D100
> >Date: Tue, 21 Dec 2004 12:00:35 -0800
> >
> >According to AWWA D100, the force reduction factor Rf = 2.5 
> for a 10,00 
> >year recurrence period.  Is there a methodology for adjusting Rf for 
> >smaller recurrence periods?
> >
> >
> >Albert H. Grathwol
> >Phone (949) 476-3562
> >Fax (603) 971-0200
> 
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