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Re: Bracing for Nail-Plate Wood Trusses

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I am also attempting to decide how to handle this problem. I have a few
thoughts as well.

Since TPI represents essentially the manufacturers, it is not surprising
that they have specified that the EOR does this portion of the design.  Why
irritate your own members?

Where in the UBC or relevant code, does it specify that TPI's guidelines for
the division of responsibilities are the ones to be used? If it is not
referenced by the code, can't the EOR specifiy that the truss company
provide this portion of the design?  Although this may mean that no one will
be doing it...

Since the trusses are typically designed after the structure, it would seem
that the permananet bracing would have to be designed as an internal system
( no external forces on the structure ) or else some re-design would have to
be called for.

Also, the most efficent permanent lateral bracing system would require some
effort in the truss design to align webs and such in the design.  How can
the EOR get the truss company to revise their design, which would require
perhaps less cost-effective trusses, when they are not intimately involved
in the truss mfgrs work?  Anyone that does custom housing using trusses can
tell you that the nice pretty layouts shown in TPI's guidelines for
designing permanent lateral bracing are never to be found.  Also, what
incentive is their for the truss company to provide webbing that does not
need to be braced (ie using 2x4 insted of 2x3, better material, etc.) when
they get to write off the difficult bracing analysis to the EOR?

I have seen a few truss companys that have been specifying 't' bracing to
eliminate the lateral bracing requirements.


Anyone else care to comment?

Pat Clark, P.E.

----- Original Message -----
From: "Kris Hamilton" <kph(--nospam--at)geigerengineers.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Thursday, March 13, 2003 4:18 PM
Subject: Bracing for Nail-Plate Wood Trusses


>
> I know this is an issue that was discussed several years ago, but I do not
> know if a consensus (or an accord) has ever been reached.
>
> The Plated Truss Institute still insists that the EOR should be the one to
> design the bracing for the web members, along with the connection of the
> bracing to the web members and the connection of the bracing to the
> structure.  What a shift of liability!
>
> I, of course, continue to believe that this ought to be dealt with by the
> truss manufacturer or designer, since it something that cannot even
remotely
> be known by the EOR until after shop drawings are received.  Their
handbook
> even acknowledges that the "building designer" might be the home-owner or
> contractor - then goes on to say that they should perform this engineering
> design function.
>
> The local building department just realized that this is not being done on
> most of the buildings they see, so they want to see an engineer design the
> web bracing for each truss roof that is specified by an engineer (I don't
> know what they are doing for "house-designer" projects).
>
> Is anyone aware if there has been any further action on this issue?  Or is
> everyone but me just buckling under and doing the design?  How many were
not
> even aware that there was an issue here?
> --
> Kris P. Hamilton, P.E.
> Geiger Engineers
> 114 West Magnolia Street
> Suite 505
> Bellingham, WA  98225
> Ph: 360 734 7194
> Fx: 360 734 7399
>
>
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