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Re: R values

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Title: Re: R values
This would be the effort that I mentioned (without specific document reference as I did not recall it) in my post to actually come up with a “rational” engineering method for the R-values.  I have not kept up to speed with it, but I knew it was taking place and had seen several presentations at different times on the effort.  I do know that there was some highly subjective decisions made that some material groups were not happy with as they felt it penalized their material.  I do not know how all that played out, but I felt some of their concerns were valid from what I recall.

But, the end result is that current R-values are still the “hocus pocus” values, as far as I know.  It will most likely take another code cycle or two before this more “rational” engineering method results in R-values (and other factors) in the code.


Adrian, MI

On 10/6/09 12:43 PM, "Tim Rudolph" <PinyonEngineering(--nospam--at)> wrote:

Fema P695 has 400 pages to guide the determination of an R-value - the publication blurb is listed below.  
The publicacation date is June 2009
Quantification of Building Seismic Performance Factors FEMA P695
This publication presents a recommended methodology for reliably quantifying building system performance and response parameters for use in seismic design. The parameters or “seismic performance factors” addressed include the response modification coefficient (R factor), system overstrength factor, and deflection amplification factor. The methodology is a refinement of an earlier preliminary methodology, and is based on a review of relevant research on nonlinear response and collapse simulation, benchmarking studies of selected structural systems, feedback from an expanded group of experts and potential users, and evaluations of additional structural systems conducted to verify the technical soundness and applicability of the approach. This draft document has been released for public comment and interim use.

Tim Rudolph
Pinyon Engineering