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Re: Parallel Chord Wood Floor Trusses

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After reading the article I have some doubts with the wood floor truss industry. I would probably not use them on the project and would look for an alternative such as I joists, Steel Joists, etc.

See the steel joist with web openings on the market. It allows duct work to be ran through.

James






From: "Chris Meyer" <chris.meyer(--nospam--at)shellandmeyer.com>
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: Parallel Chord Wood Floor Trusses
Date: Tue, 31 Dec 2002 13:44:29 -0500

Here's a question to get everyone's New Year rolling...I am curious to know if anyone has had a problem with using metal plate connected wood floor trusses. I've mostly dealt with I-joists here in Ohio, but the contractor on this job requested to use floor trusses. This made sense since there will be a significant amount of ductwork that will be going through the webs. However, I recently encountered a report published by an engineering firm in Austin,TX that documents in-service failures of these trusses. According to the report the ultimate capacity of the tested metal plate connections is less than what is determined by accepted industry standards (ANSI/TPI 1995). This resulted in plate peeling and tooth withdrawal. (You can review the report at http://www.amstarengineeringinc.com/trussresearch.pdf ) Here's my dilemma...1) The job is already in the shop drawing phase so alternate floor systems at this time are not an option 2) The report looked at residential loads (40 psf LL) and the floor trusses I have specified will have a live load of 100 psf. If this were a residence I wouldn't be AS concerned with it as I am with this public use facility. To top things off the architect has specified a 1/4" slate tile on most of the floor so any excess deflection/slip will be a problem. I will not be sealing the truss shop drawings, but with this new found knowledge, and as the EOR I thought I should investigate this further. Sorry this is so long winded, but I think this may be a very important issue. The report brings up other interesting items, but I'll let those interested read that. I will most likely have at least two trusses tested to twice the live load to insure their performance.

Any input will be GREATLY appreciated.

Happy New Year (Go Buckeyes!)

Chris Meyer, EIT
chris.meyer(--nospam--at)shellandmeyer.com



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