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RE: Truss permanent bracing

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The options are:

1) Provide lateral bracing which incidently only works well if a) the web members of adjacent trusses line up and b) the contractor actually installs it.

2) Require the contractor to create a T-section out of each web member that requires lateral bracing. In fact, this maybe the only practical solution where web members of adjacent trusses do not line up.

3) Require the contractor to install a metal web brace which does the same as the T-section. I used to know the name of this product but can't seem to find it right now. Does anyone know the name or manufacturer?

For those that want to put it back on the truss supplier or contractor, 2) or 3) sound like possible options.

Jim K.

-----Original Message-----
From: Jordan Truesdell, PE [mailto:seaint1(--nospam--at)truesdellengineering.com]
Sent: Wednesday, August 17, 2005 1:33 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Truss permanent bracing


I've yet to see a shop drawing submission that does not include language 
to the effect that the manufacturer adheres to the TPI requirements, aka 
no truss bracing. Most show locations of bracing, but no overall plan.  
A horizontal bracing member merely insures that all the similar webs in 
a line will fail together.  Since slender members are based on the 
minimum thickness, and that is universally 1.5", the architectural 
design (pitch+span) will tend to force the webs beyond the slender 
point.  Aside from going to n-ply trusses all over the building (can you 
say "unhappy owner"?), they're limited by the geometry given.  I think 
you at least need to give them bracing points and allowable values on 
the structure if you expect them to even try to brace.  My guess is that 
this is an unwinnable battle for individual firms using notes.  Sadly, 
we (SEs) are not nearly as organized as the TPI when it comes to forcing 
this issue to the ICC.

Andy Heigley wrote:

>We have talked about this several times in our firm about this topic.  And
>finally resolved to state in our General Structural Notes and specs, to
>specifically state something to these effects:
>
>THE DESIGN OF ALL WEB MEMBER PERMANENT BRACE SIZES AND CONNECTIONS, REQUIRED
>FOR THE STRUCTURAL ADEQUACY OF THE TRUSSES, SHALL BE THE SOLE RESPONSIBILITY
>OF THE TRUSS SUPPLIER.
>ADDITIONAL MEMBER PERMANENT BRACE SIZES AND CONNECTIONS, NOT PROVIDED BY THE
>SHEATHING SHOWN ON THE CONSTRUCTION DRAWINGS, SHALL ALSO BE THE
>RESPONSIBILITY OF THE TRUSS SUPPLIER.  THIS BRACING CAN INCLUDE, BUT IS NOT
>LIMITED TO, TOP CHORD BRACING FOR TRUSSES WITH PIGGY-BACKS, AND INTERMEDIATE
>BRACES FOR GABLE TRUSS WEB MEMBERS.
>
>It is the Truss designer's choice to use a slender member.  If he wants to
>use a slender member and brace it so it works, then he should provide the
>bracing for it.  So far, we've had no arguments from truss suppliers
>regarding this note, and I'll even say I've checked shop drawings that calls
>out the bracing for web members.
>
>So that's my 2 cents.
>
>Andy Heigley, PE
>
>Dublin, Ohio
>  
>


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