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Re: Braced Frames - Hollow Strucural Sections

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Why not just design the braces as tension members only and save yourself the
headache you are now facing for compression member design?


----- Original Message -----
From: Ron O. Hamburger <ROH(--nospam--at)>
To: <seaint(--nospam--at)>
Sent: Wednesday, May 10, 2000 8:26 AM
Subject: Braced Frames - Hollow Strucural Sections

> It is possible to use large HSS in braces of braced frames.  The
requirement on
> h/t is for "unstiffened" elements of sections.   This requirement was
added in
> 1994 to prevent braces from experiencing premature local buckling and "oil
> canning."  When this happens, very large strains occur at the yield lines
in the
> local buckle and fracture initiates after a few cycles.
> It is possible (and laboratoy testing has demonstrated this) to fill the
> with a noncompressible material, such as cement grout, and use lower h/t
> The grout fill stiffens the tube so that the faces are no longer
> elements."  This prevents the local buckling from occuring.
> Refer to the papers by Hassan and Goel, 1991 and Goel and Tang, 1989 upon
> this code provision is based.