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RE: BRACED FRAMES

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Hollow Structural Sections (HSS) have performed very poorly in low-cycle fatigue
tests.  Therefore they have more restrictive b/t ratios for seismic
applications.  These restrictions were also in the 1994 UBC (Section 2211.7.3)
and are not new.  Yes, you are still effectively precluded from using large HSS
sections in high seismic zones.

Rick Drake, SE
Fluor Daniel, Aliso Viejo

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Matthew Jordan <MattJ(--nospam--at)CRJARCH.com> on 05/07/2000 03:47:00 PM

Please respond to seaint(--nospam--at)seaint.org

To:   "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
cc:

Subject:  RE: BRACED FRAMES


greetings
97 code sec. 2213.8.2.5 (or .9.2.4) requires w/t ratio for braced frames <
than 110/root Fy= 16 for 46ksi tubes which is 1/16 inch of thickness for
every inch of tube. Fine until you go bigger than 10 inch tubes (5/8 inch
wall). There are none thicker in AISC for 12,14,16 inch tubes. Have we just
eliminated the use of big braced frames in warehouse type buildings?? Does
the title "Compression elements in braces" mean vert. col. also or just
diagonal brace when in compr.?
TIA
matt jordan

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