Friday, November 16, 2007

Re: USGS Web address for determining IBC SDC and Base Shear

I would say that if the accelerations are close and knowing the uncertainty that goes into the seismic accelerations, I vote that they are both correct.  Are we expecting more "accuracy" than reasonable on a model of a natural event?
 
Paul.
Phoenix, AZ

 
On 11/16/07, Larry Hauer <lrhauer@hotmail.com> wrote:
To continue with Dennis's question regarding how to determine the mapped spectral acceleration values for a specific location, I have found there are two sources, one is the USGS website using the Java Ground Motion Parameter Calculator, and the other is the FEMA 450-CD which is available free from FEMA, (800-480-2520). They are both based on 2003 information, BUT, interestingly they each give different results for a specific latitude and longitude, (not much difference- but definitely different). Again, they both say they are based on 2003 FEMA?USGS information, and the output "format" appears to be similar, ( i.e. USGS output).
 
Any ideas on which is "more" correct, and why?
 
Thanks in advance,
 
Larry Hauer S.E.





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