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Re: Re: Bracing for Nail-Plate Wood Trusses

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Just a little more discussion on previous posts.  My concern is whether the delegation of design responsibility as mandated by ANSI/TPI-1 1995 can be modified by carefully worded contract documents.
 
>FBC 2319.17.2.1  Wood Trusses
>
>This section covers all the responsibilities of truss design. All bracing
>design and detailing, along with connections between trusses, are to be on
>the truss shop dwgs. It is somewhat unclear whose responsibility it is to
>design the bracing to main structure connection.
 
I might point out that this section of the code applies to the High Velocity Hurricane Zone which is basically Broward & Dade County (Florida).  I'm not sure this would be useful in determining the delegation of responsibility for the rest of Florida.  I suspect that the State Board of Engineers would hold me to the language in Chapter 61 of the Florida Administrative Code which I referenced in an earlier post:
 
61G15-31.003 Design of Structures Utilizing Prefabricated Wood Components.
(1) Apportionment of responsibilities between Structural Engineer of Record (Building Designer) and Delegated
Engineer (Truss Designer) shall be as set forth in Chapter 2 of ANSI/TPI 1-1995.
 
>I think the TPI and the State Truss Manufacturers Associations have done
>a great job lobbying the code writing organizations and enforcement
>entities to get their requirements included in the codes and enforcement
>procedures. I know they are very active in our state.
>What have our professional organizations (representing structural
>engineers)done to protect our interests in this regard? Are they aware
>that it is an issue? Are we letting our opinions be heard? Are any of us
>active in writing these codes? Can all of us agree on one approach? As
>long as we are divided on the best approach to this issue, our influence
>may not be effective.
   
This is all true, however ANSI/TPI-1 Chapter 2 (now ANSI/TPI/WTCA 4 2002) is a "consensus" document.  That means structural engineers were supposedly involved in the development and approval of the document in the first place.
 
>Interestingly enough, the "Metal Plate Connected Wood Truss Handbook," 2nd
>Edition, Wood Truss Council of America, 1997, does *not* consistently place
>the responsibility in the same way that the TPI does. 
 
For better or for worse this is no longer true.  TPI and WTCA now have the same standard as of last year.  ANSI/TPI/WTCA 4 2002 is a consensus standard which has already received the nod of approval from the ICC.  It will be invoked by the 2004 IBC.
 
One hopeful piece of information is the following language printed at the bottom of the ANSI/TPI/WTCA 4 2002 document on WTCAs website.  This text does not appear to be part of the Standard itself but is intended to be a disclaimer:
 
"These recommendations should not be interpreted as superior to the project Architect's or Engineer's design specification for handling, installing and bracing wood trusses for a particular roof or floor."
 
...now if the state board mandates ANSI/TPI-1 Chapter 2 1995 as the document which apportions design responsibilities, then does this disclaimer apply?  That is, can my contract documents specify a different apportionment. ...I wonder...
 
Christopher A. Banbury, PE
Vice President
Nicholson Engineering Associates, Inc.
PO Box 12230, Brooksville, FL 34603
7468 Horse Lake RD, Brooksville, FL 34601
(352) 799-0170 (o)
(352) 754-9167 (f)
www.nicholson-engineering.com