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Re: Wood Floor Truss Joist Problem?

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Trusses 18" deep,  ~24" o/c spanning 24' might be slightly optomistic
depending on the LL & DL.

Any usual dead load? gyp-crete?

Who was the truss mfr?  Give them a call & discuss your concerns w/ them.

Were the calcs (stress & deflecton) done with real estimated dead &
live loads or with design loads?

Design LL / DL?  Actual estimated LL / DL?

Your measured deflection (.4" over 5' near center of span) doesn't
make sense to me............
what was it measured relative to?  


cheers
Bob

On 6/14/05, IRV FRUCHTMAN <ifaeng(--nospam--at)yahoo.com> wrote:
> Fellow Engineers,
> Here is another request for your advice: Do you know
> of structural problems with metal-plate-connected wood
> floor truss joists near the joints of its center open
> panel?
> 
> My client has noticed floor deflection increasing with
> time in his residential condo(bought new and now 1
> year old)and is concerned about potential long term
> effects – how much larger will the deflection become
> and might there be a structural floor failure in the
> future.
> 
> "Multiframe" results show that truss chords at the
> open panel have combined flexure and axial stress much
> greater than allowable. Calculated deflection is close
> to measured; calculated moments agree with those from
> the TPI empirical method. All other members have
> acceptable stresses.
> 
> Floor span is 24' and the wood trusses are 18" deep,
> with (1)-4"x2" SP#1 members. There is a 24" open panel
> at the truss center. Measured floor deflection near
> the open panel is about 0.4" over 5'. One joist bay
> beneath the troubled area is exposed and I've measured
> tributary length of 22". Metal plates and the wood
> members look OK.
> 
> If this stress result is actually true then there
> ought to be many cases where structural problems have
> occurred. I don't know of any. Have I missed
> something?
> 
> Thanks
> Irv
> 
> 
> 
> 
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