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Re: Nails etc. in Wet Wood

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The reduction actually varies depending on the circumstances and connector 
type, but 30% is nominally correct.  I will note that "circumstances" that 
I refer to are either "at time of fabrication" or "in-service" in the 2005 
NDS (and I assume the 2012 NDS, but have not checked recently).  Thus, the 
NDS does consider more that just at fabrication.

I suppose the one way to deal with the concern is to do what contractors 
typically accuse us of doing any way..."over-design" the connection.  Just 
do the connection calculations using the appropriate CsubM factor (that is 
the factor to account for moisture content) assuming a MC above 19%.

Of course, you do need to consider whether the wood is actually going to 
reach a MC above 19% just due to being installed in the rain.  Wood being 
wet on the surface will not necessarily mean the MC goes above 19%.  For 
that to even be a remote possibility, the wood likely would have to be 
sitting out in the rain for long periods of time such that it gets 
"soaked".

Beyond that, you need to consider what will happen with the wood when it 
gets to "in-service" conditions.  In the case of a building, then that 
means fully enclosed meaning the wood is likely now in a "conditioned" 
space.  Even if that wood started out soaked, presumably it will dry out 
(at least some) due to the ambient internal temperature and humidity level. 
 Thus, long term it should be less of an issue.

In the end, you will have to decide if you are worried about it enough and 
if so, if you want to "beef up" the design.

Regards,

Scott

On Jan 15, 2013, at 12:05 AM, Mark Johnson wrote:

> Here's a beginner's question.  If I remember, there is a 30% reduction in
> the allowable strength of nails and other fasteners in sawn lumber when 
> the moisture content is 19% or above at the time of fabrication.  I see 
> houses of other buildings going up in the rain all the time, especially 
> this time of year.  And probably with box nails or gun nails too rather 
> than common nails, but that another story.
> 
> The question is how to deal with the possibility that stuff you design 
> will get built when wet.
> 
> Thanks,
> Mark Johnson
> 
> --- On Fri, 1/11/13, Paul Ransom <PRansom(--nospam--at)PaulRansom.ca> wrote:
> 
> From: Paul Ransom <PRansom(--nospam--at)PaulRansom.ca>
> Subject: Re: [SEAINT-SEAOSC] Design of Crane-Supporting Structure 
> Including Testing Load
> To: seaint-seaosc(--nospam--at)mail-list.com
> Date: Friday, January 11, 2013, 8:36 AM

Truncated 1175 characters in the previous message to save energy.

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