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Re: Performance Objectives

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Concerning codification of structures into A, B, and C levels, with C level
being the code minimum which has an intuitive logic that
developer/builder/owner could understand, the 1994 NEHRP Provisions, Table
1.4.4, Seismic Performance Category has just the reverse alphabetic
designations.  The Seismic Hazard Exposur Groups are roman I, II and III and
the Seismic Performance Categories range from A for the lowest Av values of
Av<0.05 to Seismic Performance Category E for Seismic Hazard Group III for
essential facilities and 0.20 greater than or equal Av.

In other words, the Seismic Performance Categories and the requirements with
each Seismic Performance Category increase from A to E, which is counter-
intuitive from our school days report card grading A is highest to D and E
being the lowest.

The same arrangement of A being the lowest and D being the hightest exists in
the Table 1613.3.3.1-1, International Building Code, May 1997 Working Draft. 

Through the years I have found these REVERSE Seismic Performance Categories
confusing and have always had to look them up in these Tables to keep them
straight in my mind.

I agree with your A being the highest to C being the lowest rating system
because I believe the public/owner/builder/developer will understand this
"school day report care grading system" rather than the current 1994 NEHRP
Provisions (I assume 1997 NEHRP will be the same) and proposed May 1997
Working Draft of the International Building Code.

I am not sure at this late date we can propose such a fundamental change in
either the 1997 NEHRP Provisions or the proposed International Building Code.


Frank E. McClure     FEMCCLURE(--nospam--at)aol.com