Return to index: [Subject] [Thread] [Date] [Author]

Re: Braced Frames - Hollow Strucural Sections

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Why not just design the braces as tension members only and save yourself the
headache you are now facing for compression member design?

Mark


----- Original Message -----
From: Ron O. Hamburger <ROH(--nospam--at)eqe.com>
To: <seaint(--nospam--at)seaint.org>
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
tube
> with a noncompressible material, such as cement grout, and use lower h/t
ratios.
> The grout fill stiffens the tube so that the faces are no longer
"unstiffened
> elements."  This prevents the local buckling from occuring.
>
> Refer to the papers by Hassan and Goel, 1991 and Goel and Tang, 1989 upon
which
> this code provision is based.
>
>
>
>