Seismic Acceleration Look-up

[RichRook]

Hello group . .

I recently set up this website for looking up seismic accelerations very accurately by entering addresses. This is something I worked on a long time ago, but just recently finished up with and set up a professional web site.

it's at

http://www.rookrook.com

It uses the latest seismic data per IBC 2006

So far I've gotten good feedback on the site - give it a shot (no ads/registering or anything like that)

Thanks
Rich

 

[COEngineeer]

Isnt there one already on usgs.gov by inputting zip codes?

Never, but never question engineer's judgement

 

[MikeE55]

I used it as a quick check on the seismic for some of my projects. Looks like good work.

 

[JAE]

RichRook,

Before folks start blindly using your site, could you please provide a description, either here or on your site (or both preferrably) as to how these numbers are generated?

I have an initial concern that if it is based on the purely USGS data, that some areas aren't valid per the IBC. We used to use the USGS terms off their website but they recently posted a warning that the values aren't always valid for all parts of the US, specifically in high seismic areas.

Also, many cities and jurisdictions specify particular S values for their areas that are different than the posted AISC or USGS values. My own city, for example, uses two specific S1 and Ss numbers that are different that what I got by using your site.

So just suggesting that it might be good to qualify your site and numbers....a lot.

Otherwise, very handy to use I'm sure. Has it been quality checked a lot to verify its accuracy?

 

[RichRook]

There is some information on the FAQ page - which I do mean to expand upon - maybe I'll also make that FAQ link clearer.

The information is directly from the USGS data set (2002 version). It was tested against the USGS Java program . . running in a batch mode, about 10,000 random (and some not random) locations were compared with good results - a maximum of 0.001 difference - generally conservative and it ended up having a lot to do with how the USGS program rounded 5's.

The maps reprinted in the ASCE-7 are produced by USGS based on the 2002 data-set. . which is what my website uses. If a municipality has adopted specific values or requirements not part of the IBC (or ASCE7) then naturally these values will be wrong (just as the USGS maps or program would be wrong)

Rich Kipke

 

[JAE]

Just pay attention to this warning on the USGS website:

[blue]Important Note on Use of New 2008 USGS Hazard Maps

Although it is anticipated that the new 2008 USGS hazard data will be the basis for the seismic design maps in future editions of the NEHRP Recommended Provisions, the ASCE/SEI 7 Standard, and the International Building and Residential Codes, the values on those seismic design maps are expected to be materially different from the values on the 2008 hazard maps. More specifically, it is anticipated that …

1. the USGS hazard values will be amplified by factors that convert (approximately) to spectral response accelerations in the maximum direction of ground motion,

2. these factored hazard values will be multiplied by “risk coefficients” that adjust for a target risk (namely 1% probability of collapse in 50 years), and

3. these factored and adjusted hazard values will be capped near known active faults by so–called deterministic ground motions (like the USGS hazard values were for the design maps in current editions of the model building codes).

Thus, the 2008 USGS hazard maps should not be substituted for the model building code design maps nor should they be used with ASCE/SEI 41 or 31 for seismic rehabilitation or evaluation. [/blue]

Here's the link:

http://earthquake.usgs.gov/research/hazmaps/products_data/2008/disclaimer.php

 

[RichRook]

Thanks JAE - I actually already have that linked on my FAQ page. (

http://rookrook.com/faq.html#quiz6)

My website uses the 2002 database which is what that disclaimer is saying to do (and what the building code requires)

Rich

 

[JAE]

Thanks Rich... just making sure it can be used as is. Looks good.