Need a book? Engineering books recommendations...

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

Re: Tension rod bracing

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Ganesh,

your are correct. the R- value should be lower.
Please see Paper on " Hysteretic modelling of x-braced shear walls" by: Natividad Pastor and Antonio Rodriguez-Ferran, Thin-walled structures, Vol. 43, 2005, pp. 1567-1588.

Himat

>>> cethia(--nospam--at)gmail.com 06/16/06 6:49 AM >>>
I think the R factors for such bracing types went down to 3.25 from 5 and I
am interested in knowing the rationale behind this move. I have tried
finding literature related to work
regarding the behavior of Tension only rod bracings, but they are often
dated and from out of the US (Japan and Australia) hence hard to get a hold
off.

Ganesh


On 6/16/06, Syed A Masroor <masroor(--nospam--at)eaworld.com> wrote:
>
> Can Charlie or some one tell us WHY tension only systems are being so
> restricted by the new codes? Is it something theoretical or performance
> related ? After all, we have lived with them for so long.
>
> S A Masroor
>
> ----- Original Message -----
> From: "Harold Sprague" <spraguehope(--nospam--at)hotmail.com>
> To: <seaint(--nospam--at)seaint.org>
> Sent: Thursday, June 15, 2006 11:26 PM
> Subject: RE: Tension rod bracing
>
>
> > What you stated is true.   I was presuming that Drew was wanting to
> remove
> > an SCBF and replacing it with a tension only OCBF.  But tension only
> OCBF's
> > are are very restricted more by the IBC and ASCE 7 as opposed to AISC.
> The
> > original concept (crafted in the secret code development room on a far
> away
> > planet) was to just allow tension only OCBF's for PEMB's only for
> buildings.
> >
> > Obviously, there are more variables that need attention.  But the
> > fundamental question of using a tension only OCBF is that they are
> allowed
> > under some limited circumstances.  Some of the best performing
> structures
> > around are the tension only braced systems used for elevated water
> towers.
> > Now these are important structures, and they have a good track record.
> > Granted they do some special features, but the basic concept is still a
> > tension only OCBF.  By the way, we allow tension only OCBF's if they are
> > categorzed as nonbuilding structures.
> >
> > Regards,
> > Harold Sprague
> >
> >
> > >From: "Haan, Scott M POA" <Scott.M.Haan(--nospam--at)poa02.usace.army.mil>
> > >Reply-To: <seaint(--nospam--at)seaint.org>
> > >To: <seaint(--nospam--at)seaint.org>
> > >Subject: RE: Tension rod bracing
> > >Date: Thu, 15 Jun 2006 07:12:48 -0800
> > >
> > >You cannot have a specially concentric braced frame with tension only
> > >bracing
> > >without any compression bracing per AISC341-02 13.2c.  The exception to
> the
> > >30% to 70% tension brace rule says you need to have some compression
> braces
> > >designed for special load combinations in any line of bracing if you
> > >violate
> > >the 70% amount of tension braces.
> > >
> > >If you are going to have tension for a grid line they need to be
> designed
> > >for
> > >special load combinations with an ordinary braced frame R.
> > >
> > >-----Original Message-----
> > >From: Harold Sprague [mailto:spraguehope(--nospam--at)hotmail.com] 
> > >Sent: Wednesday, June 14, 2006 4:21 PM
> > >To: seaint(--nospam--at)seaint.org 
> > >Subject: RE: Tension rod bracing
> > >
> > >As with everything else.... it depends.  Are you using ASCE 7 or IBC,
> and
> > >which edition?
> > >
> > >The 2002 AISC Seismic Provisions do not preclude tension rod bracing.
> What
> > >will limit the applicability is the ASCE 7 or IBC.  The biggest
> variables
> > >are:
> > >A.  Seismic Design Category.  Since you are using a SCBF, I would
> presume
> > >that you are in SDC D, E or F.
> > >B.  Height
> > >
> > >Look at ASCE 7-05 Table 12.2-1.
> > >
> > >Regards,
> > >Harold Sprague
> > >
> > >
> > >
> > >
> > >
> > > >From: Drew Morris <dmorris(--nospam--at)bbfm.com>
> > > >Reply-To: <seaint(--nospam--at)seaint.org>
> > > >To: SEAINT <seaint(--nospam--at)seaint.org>
> > > >Subject: Tension rod bracing
> > > >Date: Tue, 13 Jun 2006 09:18:26 -0800
> > > >
> > > >Under the 2002 AISC Seismic Provisions is tension rod bracing
> prohibited?
> > > >We have a case where the building will be designed as a special
> > > >concentric braced frame, but the architect is objecting to those
> braces
> > > >that will be in front of large windows.  Can tension rod bracing be
> > > >used for these locations?  The building is a 2 story structure and
> the
> > > >braces will be on both levels.
> > > >
> > >
> > >_________________________________________________________________
> > >Don't just search. Find. Check out the new MSN Search!
> > >http://search.msn.click-url.com/go/onm00200636ave/direct/01/ 
> > >
> > >
> > >******* ****** ******* ******** ******* ******* ******* ***
> > >*   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 
> > >******* ****** ****** ****** ******* ****** ****** ********
> > >
> > >******* ****** ******* ******** ******* ******* ******* ***
> > >*   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 
> > >******* ****** ****** ****** ******* ****** ****** ********
> >
> > _________________________________________________________________
> > Don't just search. Find. Check out the new MSN Search!
> > http://search.msn.click-url.com/go/onm00200636ave/direct/01/ 
> >
> >
> > ******* ****** ******* ******** ******* ******* ******* ***
> > *   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 
> > ******* ****** ****** ****** ******* ****** ****** ********
>
>
> ******* ****** ******* ******** ******* ******* ******* ***
> *   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 
> ******* ****** ****** ****** ******* ****** ****** ********
>

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