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Re: Effective Peak Acceleration to Velocity Related Acceleration

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With a return period criteria of 1000 years I presume this is a large
government project (a dam, a desalination project, a military project,
etc), and it's clear that the UBC is not your governing criteria for
this project.  I would be very hesitent, if I were you, to try to apply
the UBC to your projsct.

I would review the criteria for the project and 'insist' that a new
consultant be brought on board to provide you with the data you need.

Lew Midlam, PE

Eqbal M. Kassam wrote:
> I am looking for any formulas or rule of thumb to convert "Peak Ground
> "
> accelerations to "Effective Peak Velocity Related Accelerations ". I
> have ASCE 7-93 which provides definition of these accelerations, i.e
> Aa
> and Av, the difference being the periods.
> Actually I have a "Seismic Response Assessment Report" from a
> consultant
> done long time ago for my project, located in Middle East. This
> consultant is no longer providing any services to the project.
> The report states  "For 1000 Average Return Period (criteria for this
> project), the computed Mean Peak Ground Acceleration is 0.183g". The
> report also provides Mean Ground Accelerations for other return
> periods
> - 500 years is 0.127g, 5000 years is 0.354g and 10,000 years is
> 0.452g.
> It does not provide any information on Velocity Related Acceleration.
> How does one determine the Equivalent UBC Zone with the above
> information ? Is it UBC Zone 2B or Zone 3 ?  (UBC Return Period is 475
> years versus 1000 years on my project). The AISC Seismic provisions
> and
> ASCE categories is based on "Effective Peak Velocity Related
> Accelerations". UBC Zoning is also based on this.
> Is it safe for me to assume that this site (not located in US) is
> equivalent to UBC Zone 2B ? According to "Project Guidelines" prepared
> prior to my arrival on the project, the site was classified as UBC
> Zone
> 3. From my drawing reviews, detailing of concrete structures,
> ductility
> requirements, for Zone 3 has not occurred. It is a Lump Sum Turn Key
> Contract and the Contracor is trying to convince the owner that
> detailing for UBC Zone 2B is adequate and that there was an error in
> the
> "Project Guidelines". The majority of the structures that get effected
> are concrete and some steel connections are doubtful.
> Any comments or words of wisdom
> Eqbal M Kassam, P.E