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RE: Old Seismic Values

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You have got a bit of homework to do. This is normally in the domain of seismologists. But if you have the marching orders, the following is your homework:
* 1994 NEHRP and Commentary
* 1997 NEHRP and Commentary
* 2000 NEHRP and Commentary
* 2003 NEHRP and Commentary
* Neotectonics in Earthquake Evaluation, Krinitzsky and Slemmons, Geological Society of America * DOE STD 1020-94, Natural Phenomena Hazards Design and Evaluation Criteria for DOE Facilities

* The Hazard in Using Probabilistic Seismic Hazard Analysis for Engineering, Krinitzsky, Environmental & Engineering Geoscience Winter 1998 * USACE Paper S-73-1, State of the Art for Assessing Earthquake Hazards in the US, Report 29, Krinitzsky

The NEHRP documents were developed by the BSSC Some of their documents are available on line. Some of the older ones will probably not be available on line.

If it were up to me, I would call Geomatrix, URS, USACE, or USGS in Boulder. You will find guys like Maury Power, C B Crouse, Ellis Krinitzsky, E V Leyendecker, Art Frankle, Ted Algermissen, and Dave Perkins who are the real movers in the field. I have been envoloved in seismic engineering for about 17 years and envolved in code development for about 10 years, I would hire one of the guys.

What you are needing was the result of a radical evolution that took place over a 10 year period. In the early days the Algermissen and Perkins charts were what was used for zone development and were 20 years old before we went to true seismic spectral ordinates. Ted Algermissen first proposed a seismic spectral ordinate chart in about 1995. It just took us a while.

Harold Sprague

From: "Jason W. Kilgore" <jkilgore(--nospam--at)>
Reply-To: <seaint(--nospam--at)>
To: <seaint(--nospam--at)>
Subject: RE: Old Seismic Values
Date: Wed, 11 Aug 2004 18:21:17 -0500

> I don't know why you are even trying to use the old data.

Because the client said, in effect, "Thou shalt use this document in your
design".  The document specifically states the acceleration and velocity
values I gave earlier.  I *know* that the values are wrong; my problem is
that I have to explain to the client why they're wrong, how much they're
wrong, what are the right values, and why they are the right values.

In order to do this efficiently, I need to completely understand exactly
what the old values are, and how they relate to the new values.

Again, I realize that these are very low numbers, but the difference in the
report value (5%, 475 yr. return) and new values (2.1%, 475 yr. return)
could mean the difference between adding bracing to all mechanical units or
strengthening existing 20' tall URM shear walls (in plane and out-of-plane).

Jason Kilgore
Leigh & O'Kane, LLC
Kansas City, Missouri

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