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Re: R value for log walls

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Thanks for your comments. I have been away since posting my 
message. I was rushing to catch a plane while preparing the 
message, so I may have been a little vague about which R value I 
wanted info on. R = Response modification factor as I am 
developing a Mathcad template for seismic design....

Charles, thanks for your suggestions on developing an R value for 
log buildings. I will persue this, purely on the basis of...someone 
has too. I am suprise that no one has done any 
research/design/development as there are a lot of log home 
manufactures out there, and a lot of buildings requiring an 
engineers approval. 

The journey begins.....

Peter McCormack

Date sent:      	Wed, 08 Dec 1999 15:59:28 -0800
To:             	seaint(--nospam--at)
From:           	Charles Greenlaw <cgreenlaw(--nospam--at)>
Subject:        	Re: R value for log walls
Send reply to:  	seaint(--nospam--at)

> At 02:31 PM 12/8/99 -0500, you wrote:
> >I am in the process of developing a MathCAD template for 
> >determining seismic loads per UBC.
> >
> >However, I need to determine a realistic "R" value to assign to log 
> >walls acting as both shear and load bearing walls. Obviously, a wall 
> >constructed of logs stacked 1 above the other has a higher density 
> >than a light framed shear panel, but is not as dense as a concrete 
> >or masonry log wall.
> >
> >Does anyone have any suggestion, is there a calculation method to 
> >determine it based on the material density???
> >
> >Any help will be appreciated
> >
> >Peter McCormack
> ------------------------
> Peter, a great opportunity knocks for you.
> Other replies, especially by "sasquake", call attention to the committee
> process as the source of seismic R values for various forms of construction.
> It appears that no committee has yet undertaken to set an "R" for log
> houses. In my experience on such committees, and following things since
> then, a special coefficient for such an esoteric form of construction would
> be tasked to one single person. If that person came back with a lot of
> numbers on paper, etc., and presented the recommended outcome in a
> self-assured, authoritative manner, then acceptance by the rest of the
> committee with little hassle is very likely. Once that happens, the outside
> reviews and cementing of the R factor outcome with the vaunted "consensus
> process" proceeds apace. Ben Yousefi told us how that consensus position
> becomes impenetrable armor against later challenge, especially one from an
> individual.
> So, you aren't on the committee, let alone a long-term member of it? For
> shame! But all is not lost: Imagine you are a committee member, using
> affirmation techniques and whatever else it takes to become a believer.
> Behold: The committee has given you the job of developing the "proper"
> R-value for log houses. Do it. Read up on the SEAOC Blue Book Commentary,
> and maybe ATC and NEHRP commentaries to get a flavor of the rationale and to
> pick up ease with the jargon. Then make up your mind firmly and set forth
> your R value with resolve. That's how to do it. 
> You don't have to furnish any scholarly explanation, or even any simple one,
> because someone else writes up all that for the next edition of Commentary
> later. Just be forceful in presenting it orally in committee, in your mind.
> Then use this R value. 
> Now, watch out for any second thoughts. You absolutely have to wrap yourself
> in the mystique of committee membership, in your mind, even though you are
> an individual. This is the magic that distinguishes you from any other
> individual, such as the hapless one who submits a challenge during that
> eleventh hour step in the final code approval process.
> Good Luck, and Unshakeable Resolve. When you're done, tell us what R value
> we have to follow. Logs "R" Us.
> Charles O. Greenlaw, SE  Sacramento CA