Friday, January 16, 2009

Re: Lateral Stability of a Box Beam ?

This may not be much help, but I reviewed four fire halls in Fort Erie
(across the river from Buffalo) for structural integrity. One of them
had what appeared at first glance to be poured concrete beams until I
noticed a hole in one. They turned out to be plywood box beams,
trapezoidal in shape, wider at the top. I believe I asked the list at
the time and no one was able to give me a specific answer but someone
seemed to recall that these were being promoted at the time (1950s?) by
the plywood industry? Perhaps there is someone out there who can help. I
would like to learn more about them also.
Gary

Bill Allen wrote:
>
> I have a situation requiring two beams, approximately 12" apart
> spanning about 27 feet. They aren't supporting much more than their
> own weight, but I'm concerned that if I just use the span as the
> unbraced length, the beams are going to be very large.
>
> I would like to put plywood top and bottom to increase the effective
> lateral torsional strength. Is there a good reference in determining
> the capacity of such an assembly in wood?
>
> Thank you,
>
> T. William (Bill) Allen, S.E.
>
> ALLEN DESIGNS <http://www.AllenDesigns.com>
>
> Consulting Structural Engineers
> V (949) 248-8588 • F(949) 209-2509
>

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