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[SEAOC] Re: [SEAOC] Re: [SEAOC] Truss discussion.

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Neil:
These are some good questions and I hope they will generate some discussion.
I'll respond to number 1 and 3.  (Regarding item 5, I don't see how Section
3.4 is involved is connected to shrinkage.) Frank Woeste

At 01:55 PM 8/13/96 -0700, you wrote:
>Frank:
>
>Thank you for your reply to some of my questions.  I also received the WTCA
>1-1995 from you and your commentary and have some further comments and
>questions.
>
>1.      What if there isn't a building designer or engineer for a project;
i.e. 
>only the contractor is involved, such as for conventional light-frame 
>construction?  Who now is responsible for the web bracing?

According to WTCA 1-1995, the "Building Designer is the individual or
organization having responsibity for the overall building or structure
design....."   In the case you cite, the Contractor is also the "Building
Designer." 
>
>2.      There appears to be no provisions for any submittals to a building
>department.  Many building departments accept the truss data after the fact -
>not a good idea, but real world.  
>
>3.      How high of a temperature would affect the long term strength of a
>truss?

According to recent research at the U. S. Forest Products Lab on clear pine,
continuous exposure at 150F (24 hours per day) will cause the wood to lose
strength.  They are now completing their 4th year of temperature exposure at
150F.  Dr. Dave Green is the lead researcher.  His telphone number is
608-231-9261.
The standard answer on this subject is given by the ANSI/NFPA NDS-1991
National Design Specification for Wood Construction, Table 2.3.4.  It gives
reduction factors for sustained temperature exposure between 100 and 150F.
The word "sustained" is important in using this table.
>
>4.      What effect would be from the moisture content going from a kiln-dried 
>material of 15% to less than 6%?   Would this be a similar situation to use
>a 20% reduction of the allowable plate value when plates are installed at a
>19%, per 
>4.2 of TPI-85?
>
>5.      We have found with the lowering of the moisture content, there is a
>corresponding reduction of the cross sectional area and therefore the member
>no longer size no longer conforms to Section 3.4.  Any comments?  
>
>
>
>
>Neil Moore, S.E.
>
>...
>
>

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