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Re: length to be used for tension bracing kl/r

[Subject Prev][Subject Next][Thread Prev][Thread Next] Often the controling factor for HSS sections used as braces are the b/t ratio
requirements, at least in seismic Zone 4, which has an impact on Kl/r ratios
and likely results in Kl/r ratios less than 200 and 300 for the given design
loads.  I would agree these limitation are not relevant relative to stiffness
and stress, but I would think it helps promote better behavior during cyclic
loading of a member and fatigue, especially if some inelastic behavior is
expected.

Michael Cochran S.E.  



In a message dated 6/28/2001 3:41:46 PM Pacific Daylight Time,
rakamaka(--nospam--at)yahoo.com writes:


While going through examples in the seminar, I noticed
that the limiting slenderness ratios were never used
in determining the allowable stresses. When I
questioned, Dr. Yura, about the existing requirement
on limiting slenderness ratios, he said that they are
not relevant. Perhaps, the committee on the code
provisions decided to retain the minimum kl/r
requirements.

Rajendran
--- Rick.Drake(--nospam--at)Fluor.com wrote:
>
> The latest LRFD Specification (December 27, 1999)
> will be bound in the next
> LRFD Manual, 3rd Edition, later this year.  Section
> B7, Limiting
> Slenderness Ratios, remains unchanged.  Preferable
> slenderness ratios are
> still 200 and 300 for compression and tension
> members respectively.
>
> New LRFD Specification Section C3, Stability
> Bracing, reflects Yura's
> excellent work in defining the required brace
> strength and stiffness for
> the stability of the braced member or structure.
> These requirements are in
> addition to the long-standing slenderness
> preferences.
>
> Rick Drake, SE
> Fluor Daniel, Aliso Viejo, CA
>
> ***********************
>