Ground Motion Input for Site Response Analysis

[moe333]

I am performing a site response analysis (SRA) for a deep, stiff soil site where Vs is about 800 ft/s for hundreds of feet (site Class D), and I am using a non linear effective stress code. There are many opinions regarding the development and implementation of input ground motions.

I am using ground motions recorded on site class B (since these are generally considered to be un-modified) and scaling/modifying the ground motion so that the spectrum from the recorded ground motion is similar to the Site Class D, MCE 2007 CBC response spectrum at the specific location.

I am then inputting the ground motion at a depth of about 100 feet into the code and assigning the ground motion a Vs of 800 ft/s, similar to the site specific Vs at the site and depth.

Any comments on the methodology are appreciated. I am aware of the NEHRP commentary and realize my method is different.

Thanks

 

[msucog]

try this site since i'm certain you will find help there

http://nisee.berkeley.edu/

you can search the abstracts and then pay $25 a year if you find good stuff there. i've found that it's the best (and most cost effective) resource for earthquake related stuff. there's a couple of papers by "the seismic gurus" that discuss all sorts of things including what you are working on. many of the papers are pretty "deep" to me but i suppose that should be expected due to the complexity of the subject.

from the little bit i know, it sounds like you're taking a reasonable approach.

also check out

http://www.ez-frisk.com/

 

[Castigliano]

I'm a little confused as to why you're modifying to site class D before entering the analysis. Is this to account for the fact that you're only including the top 100 feet in your analysis, and there appear to be at least another hundred feet below that elevation to bedrock? If so, you might want to check out the work by some researchers on the "Mississippi Embayment" modeling efforts. A little vague, I know, but all I have to offer.

Castigliano

 

[msucog]

http://people.ce.gatech.edu/~sromero/maecenter/Overview.html