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

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

[Subject Prev][Subject Next][Thread Prev][Thread Next]
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

***********************



                                                                                                                   
                    Padmanabhan                                                                                    
                    Rajendran            To:     seaint(--nospam--at)seaint.org                                                 
                    <rakamaka@yahoo                                                                                
                    .com>                cc:                                                                       
                    06/28/01 11:58                                                                                 
                    AM                   Subject:     Re: length to be used for tension bracing kl/r               
                    Please respond                                                                                 
                    to seaint                                                                                    . 
                                                                                                                   
                                                                                                                   




Less than a month ago, I attended a seminar on
"Bracing for Steel Structures", conducted by the
international authority on the subject, Dr. Yura.  The
limitation of kl/r (200 for compression members and
300 for tension members) are not required. The bracing
members should satisfy only the "stiffness" and
strength requirements. Future editions of AISC Manual
(ASD or LRFD or some hybrid form) will include
detailed sections addressing bracing.

Rajendran

--- Ken Peoples <kspeoples(--nospam--at)yahoo.com> wrote:
> I seem to be constantly coming up with bracing
> member sizes that are
> controlled by kl/r instead of the force in the
> member.  I have been
> using the full length of the member when evaluating
> kl/r.  My question
> is this: for X-bracing angles that are designed for
> tension only with
> the kl/r<300 recommendation, is it reasonable to use
> a length of 1/2
> the actual length when the angles are bolted
> together at the center.  I
> know that the other angle wouldn't give it much
> lateral support to
> prevent buckling in one of the directions if I were
> designing for
> compression, but to satisfy the l/r<300
> recommendation for tension
> members, I would think that it might be OK.  I
> understand from the AISC
> 9th ed. commentary on B.7 that the recommendation is
> made to "afford a
> degree of stiffness such that lateral movement
> ("slapping" or
> vibration) will be avoided. What approach do most
> engineers use?
> Thanks for your thoughts.
> Ken
>
> =====
> Kenneth S. Peoples, P. E.
> Lehigh Valley Technical Associates
> 1584 Weaversville Road
> Northampton, PA 18067-9039
> ph: 610-262-6345
> fax: 610-262-8188
> e-mail: kpeoples(--nospam--at)lvta.net
>
> __________________________________________________
> Do You Yahoo!?
> Get personalized email addresses from Yahoo! Mail
> http://personal.mail.yahoo.com/
>
> ******* ****** ******* ******** ******* *******
> ******* ***
> *   Read list FAQ at:
> http://www.seaint.org/list_FAQ.asp
> *
> *   This email was sent to you via Structural
> Engineers
> *   Association of Southern California (SEAOSC)
> server. To
> *   subscribe (no fee) or UnSubscribe, please go to:
> *
> *   http://www.seaint.org/sealist1.asp
> *
> *   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any
> email you
> *   send to the list is public domain and may be
> re-posted
> *   without your permission. Make sure you visit our
> web
> *   site at: http://www.seaint.org
> ******* ****** ****** ****** ******* ****** ******
> ********


__________________________________________________
Do You Yahoo!?
Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
*
*   This email was sent to you via Structural Engineers
*   Association of Southern California (SEAOSC) server. To
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
*   send to the list is public domain and may be re-posted
*   without your permission. Make sure you visit our web
*   site at: http://www.seaint.org
******* ****** ****** ****** ******* ****** ****** ********





-----------------------------------------------------------------------------------------------------
The information transmitted is intended only for the person
or entity to which it is addressed and may contain confidential
and/or privileged material. If you are not the intended recipient 
of this message you are hereby notified that any use, review,
retransmission, dissemination, distribution, reproduction or any
action taken in reliance upon this message is prohibited. If you 
received this in error, please contact the sender and delete the 
material from any computer.  Any views expressed in this message
are those of the individual sender and may not necessarily reflect 
the views of the company.  
-------------------------------------------------------------------------------------------------------

******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********