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RE: "Flitch-plate" design

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I could not find them in these references either. However, I did find one in
the book "Structural Design in Wood" by Judith J. Stalnaker and Ernest C.
Harris. The design examples assume concentricly placed stiffer member
(sandwiched). It is also refered to as a "Vertically Laminated Beam". It has
one caution:
"To design any of these types, the fransformed-section method must be used.
The transformed section is an imaginary section of stiffness equal to that
of the actual reinforced beam. Its dimensions and properties are found by
imagining the steel area to be replaced by an elastically equivalent area of
wood. The elastically equivalent area of wood is the area of steel
multiplied by the ratio of the modulus of elasticity of steel to that of
wood.
Designers should be cautioned that the variations in modulus of elasticitiy
of wood affects the assumptions made. The coefficient of variation of E in
wood is around 25-30%........The action of the reinforced beams is based on
the fact that the deflected shape of the wood and steel portions are
compatible. For the flitch beam, for example, both the wood and the steel
plate bend to the same deflected shape. If the loads include long-term
loads, a lesser E-value should be used for the wood." Page 291-292
Published by Van Nostrand Reinhold - 1989.

Dennis Wish PE


-----Original Message-----
From: Bill Allen, S.E. [mailto:billallen(--nospam--at)earthlink.net]
Sent: Friday, May 15, 1998 8:21 AM
To: seaoc(--nospam--at)seaoc.org
Subject: RE: "Flitch-plate" design


I have done a cursory search in my two main timber reference texts:

Timber Construction Manual, AITC, 3rd ed.(don't laugh, I know I'm an old
geezer)
Design of Wood Structures, Donald E. Breyer, 3rd ed.

I could find no references to "flitch plates" or any other connection with
metal side plates used for the purpose of resisting bending moment.

Regards,
Bill Allen

-----Original Message-----
From: Ed Marshall [mailto:elmarshall(--nospam--at)HASimons.com]
Sent: Friday, May 15, 1998 7:29 AM
To: 'seaoc(--nospam--at)seaoc.org'
Subject: RE: "Flitch-plate" design


There is also a discussion in  ASCE's "Wood Structures, A Design Guide
and Commentary", 1975, Section 8.6.3.2:

"... defined as 'a vertically laminated beam composed of one or more
pieces of timber with one or more metal plates on the sides or between
the timbers and fastened to each other so as to act as one unit ...  at
the beginning of this century, flitch beams were quite common and
accepted in building construction everywhere' ... yet the need to
predrill both lumber and steel plate, to allow bolting, made the
assembly of flitch beams time consuming, unpopular, and uneconomical in
light of advanced technology."  It then goes on to discussion testing of
nailed assemblies using sheet steel rather than plate steel.

By the way, I've seen a least a couple to text books that included
flitch plate beam design in them, but don't have them at hand.

Ed Marshall, PE
Simons Engineering
Atlanta

> -----Original Message-----
> From:	Bill Allen, S.E. [SMTP:billallen(--nospam--at)earthlink.net]
> Sent:	Friday, May 15, 1998 9:46 AM
> To:	seaoc(--nospam--at)seaoc.org
> Subject:	RE: Need "Flitch-plate" design example
>
> In this entire thread, this post is the only one which contains a
> reference
> to a published (as opposed to "home-brew") solution. I would be very
> interested in reviewing it. If it is not too much trouble, please mail
> a
> copy to:
>
> Bill Allen
> P.O. Box 7347
> Laguna Niguel, CA 92607
>
> Thanks,
> Bill
>
> -----Original Message-----
> From: John Buchanan [mailto:jjb(--nospam--at)scruznet.com]
> Sent: Thursday, May 14, 1998 1:05 PM
> To: seaoc(--nospam--at)seaoc.org
> Subject: Re: Need "Flitch-plate" design example
>
>
> At 11:55 AM 5/14/98 -0700, you wrote:
> >My client does not want to remove and replace an existing 4x16 DF #1
> Beam
> >which will span 18'-6" once the center column is removed. The roof
> trib on
> >the member is approximately 12'6". The beam is continuous over this
> support
> >(that's being removed) and the member calculates about 22%
> overstressed in
> >bending for the 18' span.
> >He has asked if I could design him a Flitch Plate with 1/4" steel
> sideplate
> >and a 1/4" x 3" leg to rest the existing patio framing at one side.
> >I have not designed one before and am not really sure how to go about
> it. I
> >assume it is similar to a composite beam design, yet the plate is
> only on
> >one 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
> >
>
> See section 10.35 of a book called "Wood engineering and Construction
> Handbook"
> Keith F. Faherty and Thomas G. Williamson
>
> McGraw Hill
>
> I Can send you a copy of the chapter next week if you'd like
>
> John Buchanan
>