Seismic lookup by zip code 4

[mrMikee]

A site that I have used quite a bit has moved. To lookup seismic data by zip code go to the following link:

http://eqint.cr.usgs.gov/eq-men/html/zipcode-06.html

This information is based on 1996 data which is good for IBC2000/2003, generally. I think someone here at eng-tips said that there are a few errors in the values reported on the zip code lookups, so a cross check back to the map is probably a good idea.

The newer codes will be using 2002 data with lookup based on longitude and latitude.

http://eqint.cr.usgs.gov/eq-men/html/lookup-2002-interp-06.html

Regards,
-Mike

 

[archeng59]

I use Enercalc for component design. the last version (5.8) has a module for seismic where you can input the zip code to get seismic info based on ASCE 7-02. this could be an alternative to your link.

 

[mrMikee]

Some of the USGS data is not copyrighted so it would be available to the public, and I suppose could be easily integrated into software for the convenience of lookups. It would be interesting to compare the data.

-Mike

 

[WillisV]

Note that ASCE 7-02/IBC 2003 still uses the USGS 1996 data - ASCE 7-05 / IBC 2006 is the first code cycle to use USGS 2002 data.

 

[mrMikee]

Someone at eng-tips said last year that there was at least one state that adopted the USGS 2002 data early for use with the IBC2003. Which is Ok with me but it just makes it harder to keep track of.

-Mike

 

[WillisV]

Georgia approved the option to use USGS 02 as a supplement to their building code which is essentially a copy of IBC 2000.

 

[wjc]

Be careful in using zipcode lookup parameters in active, near fault areas. The parameters are based on a grid that is something like 6km square. If you are within 2km of a fault, such as the Hayward Fault, the value by zipcode (where the value is determined at the centroid of the zipcode area may be substantially in error!!

 

[fleisher]

I was at a Staad seminar in Dallas and noticed they had a similar capability in their new version. Put in the zip code and it creates a response spectrum based on the IBC graphs. But if you go to their website, there is nothing about their new version yet.

 

[Beggar]

Would one of you structural guys/gals do me the professional courtesy of interpreting what this says about my home?

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Probabilistic ground motion values, in %g, at the Nearest Grid point are:
10%PE in 50 yr 5%PE in 50 yr 2%PE in 50
PGA 29.731501 38.852032 52.698761
0.2 sec SA 70.977837 105.759598 126.108498
0.3 sec SA 63.360321 98.395309 122.763702
1.0 sec SA 25.884750 31.822069 44.953178
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


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[mrMikee]

Beggar,

We generally design for an earthquake acceleration response spectrum "defined as corresponding to to a 2-percent probability of exceedance in 50 years" per IBC section 1615.2.1. This would be column four in your post labelled "2%PE in 50." The two values of interest are Ss=1.26 and S1=0.44 for short period and 1-second period accelerations. These numbers then go into a relatively contorted (IMO) set of equations and conditions that result in equivalent seismic forces that are a percentage of W for lateral loads and a percentage of the deadload for vertical loads.

I posted a link to a few high resolution maps in thread507-152485 that will give you a better overall view of seismic risk nationally.

I don't have any recent calcs with me today, but where you live now seems to me to be getting into a little more serious area of seismic design. In the midwest I seldom see seismic forces that are more than a good strong wind.

Regards,
-Mike