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RE: Need "Flitch-plate" design example

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I guess where I am "extrapolating" information is with regards to GLB
strengthening. Years ago, I occasionally reinforced overstressed GLBs using
this method. I then ran into a GLB expert (one who has 40+ years experience
and now spends a lot of time in court as an expert witness) who said this is
a bad idea and will not perform over the long haul.

With regards to residential construction, collar ties seem to perform well
too, but they won't "calc out" based on some of the modeling I have done
(due to horizontal deflection).

My previous post was my $0.02 and was merely cautionary. My friend Dennis
Wish can do whatever he desires.

Bill Allen

-----Original Message-----
From: Ed Marshall [mailto:elmarshall(--nospam--at)]
Sent: Thursday, May 14, 1998 3:03 PM
To: 'seaoc(--nospam--at)'
Subject: RE: Need "Flitch-plate" design example


I mainly do heavy industrial design so I don't have applications for
flitch plate design often, but I do have several supporting my house.
If I recall correctly that are built with 1/4" plates between 2X10's
spanning about 16' and each one supports about 10 feet of tributary
floor width, a wall with several door openings, and then a corresponding
ceiling and roof load.  No problem with wall cracks or deflections. The
assemblies are held together with about 1/2" diameter bolts on about 4'
centers.  On the few occasions when I've designed flitch plate beams I
recall the numbers working nicely.

Ed Marshall, PE
Simons Engineering

> -----Original Message-----
> From:	Bill Allen, S.E. [SMTP:billallen(--nospam--at)]
> Sent:	Thursday, May 14, 1998 5:32 PM
> To:	seaoc(--nospam--at)
> Subject:	RE: Need "Flitch-plate" design example
> When you say that this method "works", do you mean that you can
> produce
> calculations that are satisfactory or that the built-up section
> actually
> performs the way you intended it to (i.e., stresses are adequately
> transferred to the steel plate). My concern would be that, since the
> bolts
> are in wood and will deform), no (or little) load will actually
> transfer to
> the steel plates. In my mind, this is nothing like "composite" action
> since
> the deformations of the two materials are so incompatible. If you were
> talking about welding a flange plate on a steel girder, that would be
> different.
> Obviously, I have no "warm fuzzies" about strengthing a wood beam with
> a
> steel plate.
> Regards,
> Bill Allen
> -----Original Message-----
> From: T [mailto:vicpeng(--nospam--at)]
> Sent: Thursday, May 14, 1998 2:09 PM
> To: seaoc
> Subject: Fw: Need "Flitch-plate" design example
> Dennis
> I have done this many times.
> Points to heed
> 1)    If plate is not within the timber plies, i.e. laterally
> restrained,
> you have to calculate the bolt spaces by investigating the potential
> for
> plate buckling.
> 2)    If the plate is laterally supported such as with the bottom/top
> flange
> like with an angle then with good bolting patterns the section
> properties
> can be calculated with tranformed sections methods.
> 3)    You may need t consider torsion of the transformed section
> depending
> on your load application.
> Otherwise no different from ordinary beam design.  I have used this
> for many
> instances where header depth is restricted and a full steel section is
> not
> wanted.  Works like a hot damn!
> Thor Tandy  P.Eng
> Victoria  BC
> Subject: Need "Flitch-plate" design example
> >My client does not want to remove and replace an existing 4x16 DF #1
> Beam
> only on.........
> > side and is to be lagged to the face of the existing
> beam.
> >
> >If anyone has a sample of an analysis that I can follow, I'd
> appreciate it.
> >
> >Thanks
> >Dennis Wish PE
> >
> >
> >Dennis S. Wish PE