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Re: Wood Floor Truss Joist Problem?

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Bob:
Thx for reply.

I used design loads for the calcs: LL=40 psf and DL=24
psf. Deflection parallel to the problematic joists was
measured with a laser level; deflection = O.4" is the
difference in measurements about the joist center.  

One feature that might be unusual is that the problem
joists support a bathroom tub on one side and a
refrigerator on the other side of a partition wall. I
didn't account for these loads.  

Irv


--- Robert Kazanjy <rkazanjy(--nospam--at)gmail.com> wrote:

> 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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