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Factory made trusses

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Frank Woeste wrote:

. > The design of the compression web bracing and companion diagonals required
. > to stabilize the lateral web braces is the responsibility of the building
. > designer, usually an engineer or architect in commercial construction.  
. > The "truss designer" is responsible for specifying the points on each 
. > truss that require lateral support. A reference on this matter would be 
. > ANSI/TPI 1-1995  National Design Standard for Metal Plate Connected Wood 
. > Truss Construction which has been adopted by the three model codes.  See
. > specifically paragraph 5.3 Permanent Bracing.

Hogwash!

Only the truss designer knows where compression members need to be braced and 
the bracing force.  The building designer has no knowledge of this until the 
shop drawings are received.

Regardless of what TPI 1-1995 says, my specifications will *require* that 
*all* bracing that is a condition of design of the trusses is to be specified 
and detailed by the truss designer.

The Truss Plate Institute went thru this once before (early 1970's) and at 
that time put in their specs that all bracing which is a condition of design 
is the responsibility of the truss designer.

. > There's more to permanent bracing than web bracing.  Chords under valley
. > sets, the  flat compression chord of a piggyback system, etc. require
. > permanent bracing design ...

Right, but who determines where the chords under valley sets are located?  
Who decides where compression web members go and how long they are?  Who 
determines where piggyback systems are divided?  Not the building designer!

A. Roger Turk, P.E.(Structural)
Tucson, Arizona