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Re: Question on wood Roof Trusses

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Let's throw a twist into this:

If I am "responsible" for the bracing, and the contractor/truss supplier
never submits the shop drawings, then who is really responsible?

I have to beg and plead for shop drawings on commercial stuff, let
alone residential.

Dan Goodrich, P.E.


----- Original Message -----
From: "Neil Moore" <nmoore(--nospam--at)innercite.com>
To: <seaint(--nospam--at)seaint.org>; <seaint(--nospam--at)seaint.org>
Sent: Tuesday, January 16, 2001 12:37 PM
Subject: RE: Question on wood Roof Trusses


> Tarek:
>
> If I remember correctly, one of the TPI publications has an example of how
> ALL of the webs can buckle at once.  If the web bracing isn't anchored to
> something, then this can happen.  Most of the time, the real loads never
> approach the design loads and any buckling problem has moved into the
> factor of safety area.
>
> If people are designing trusses in snow areas, say 160 pcf, then our
> discussions and the possible reprecussions become important.  My original
> involvement in the web bracing responsiblity problem came about 6 years
ago
> in a court case.  That's were I found out that the responsibility is kinda
> hidden in the TPI specification, which the UBC refers you too.  How many
> people owned the TPI spec?  Further, it is also difficult to interpret the
> results of the computer output.  That presentation can be, and may already
> have been, improved upon.  I've read where some engineers are going to get
> tough about this and make the truss company provide the web bracing
> anchorage to the building or to the roof or somewhere.  Good luck!.
>
> It still is important to review the truss company's layouts; you might be
> surprised at what you will find.
>
> Neil Moore, S.E.
>
> >Peter:
> >
> >I personally have it in my specs that bracing the truss members is the
> >responsibility of the truss designer for reasons too numerous to
> >recount.this thread was started a while back so check the archives and in
> >particular excellent postings by Roger Turk .
> >
> >I think the bigger problem is getting the framer to actually brace
> >the members that need bracing. and unless somebody shows him where these
> >members are on the framing plan
> >they aint gona walk the building with the little 81/2 x 11's from the
> >truss engineer and do it( all they see is a little astrisk next to said
> >members)
> >incidently every framer that we worked with told me that they have never
> >installed such braces and never knew they were even required .Generally
> >engineers have some sort of a typical detail on their plans that refers
> >back to the truss designer's calcs. good luck getting the framer to
> >comprehend it.
> >it is my opinion that unless the compression bracing is shown on the
> >truss layout sheet with the appropriate details refernced to it nobody
> >will follow
> >my 2 cents
> >Tarek Mokhatr
> >strucural engineer
>
>
>
>