Need a book? Engineering books recommendations...

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

Re: FW: FW: Reinforcement detailing in coupling beam

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Eric,
Thanks a lot for these helpful information. Now I'm
getting a better idea myself about the essential facts
in this situation.
I'm dealing with an existing steel structure
strengthen by new concrete shear wall. So I don't want
to touch the old steel system, simply because that the
situation will get more complicated and would involve
steel beams and etc.
However having the column at the middle, would make
the coupling beam span shorter in reality, means that
shear action will dominate for sure. Is this right?
The typical span and depth for coupling beam is 15'
and 5' respectively and steel columns and beams are
WF10. 
If this assumption would be right, it seems that I
might be able to have two coupling beam transferring
their shear load to the column at the middle. 
On the other hand, I came to this idea from your
comments that it might be better to just make the
steel beam to act like coupling beam and ingnore
diagonal rebars. 
Thanks again,
Frank


--- "T. Eric Gillham PE" <teric(--nospam--at)gk2guam.com> wrote:
> 
> 
> -----Original Message-----
> From: T. Eric Gillham PE [mailto:teric(--nospam--at)gk2guam.com]
> Sent: Saturday, October 27, 2001 11:34 AM
> To: seaoc list
> Subject: FW: FW: Reinforcement detailing in coupling
> beam
> 
> 
>
--------------------------------------------------------------------------
> This message is too long to be posted to this list.
>
--------------------------------------------------------------------------
> 
> 
> Frank:
> 
> This sounds like a complicated situation - you say
> the steel column is
> EXISTING?  What about the walls?
> 
> Short span R/C coupling beams have diagonal struts
> because the span to depth
> ratio is such that compression and tension struts
> form between the walls in
> the beam and dominate the behavior of the beam such
> that flexural action is
> pretty much non-existent.
> 
> This being the case, you are essentially designing
> diagonal "columns", and
> hoops spacing and detailing is a must if
> satisfactory peformance is to be
> relied upon.  This also goes for the development of
> the main strut bars,
> since they will yield in both tension and
> compression - in fact, as far as
> development lengths for these bars into the abutting
> walls, I usually go at
> least 1.2 times any UBC development length
> requirements.
> 
> This being the case, CONTINUOUS diagonal strut bars
> are required - they
> cannot be cut and hooked any more than the vertical
> bars in a ductile R/C
> column could be cut and restarted.
> 
> I am still confused as to the situation.  Is the
> wide flange section
> required for carrying load across the opening, or
> are there other steel
> elements (beams) framing into the existing WF col
> and that is why you wish
> to keep it?
> 
> Perhaps if you gave some idea of the span of the
> opening, and whether the
> walls are existing or not it might help.  If the
> walls and WF are existing,
> it will be tricky indeed, since developing the diag
> strut bars (see above)
> would require demolition of a rather large chunk of
> the existing wall and
> repouring of it after the diag struts are installed.
> 
> Another way to look at it is whether the coupling
> beams are actually
> required.  If you are cutting an opening in existing
> walls, can you get by
> with just the cantilever action of the newly created
> (from 1 you are getting
> 2) walls?  If not, you may even want to look at
> using a steel coupling beam
> anchored by thick plates at each wall end secured
> with a bunch of through
> bolts.
> 
> I'm having difficulty formulating a response, since
> I still cannot see the
> picture quite clearly enough.
> 
> Regards,
> 
> TG PE
> 
> -----Original Message-----
> From: Fariborz Tehrani [mailto:fmtehrani(--nospam--at)yahoo.com]
> Sent: Saturday, October 27, 2001 10:26 AM
> To: seaint(--nospam--at)seaint.org
> Subject: Re: FW: Reinforcement detailing in coupling
> beam
> 
> 
> Eric,
> Thanks for your email and comment.
> Here are some more information on this situation:
> The steel column is existing WF10 and the wall
> thickness is 18" at the lowest level and 10" at the
> highest level.
> The span is shorter than 4 times the beam depth, so
> coupling action is applicable.
> It's also notable that the steel column is at the
> middle of the opening.
> This column has not designed to carry any load other
> than gravity. However at this situation, interaction
> might occur between the coupling beam and the
> column.
> Now, what would be happened to diagonal rebars?
> Shall
> I transfer shear loads to the steel column? And in
> that case, may I cut diagonal rebars at the column
> web
> and provide standard hook or other means of
> development?
> Thanks again for your help,
> Frank
> 
> 
> ******* ****** ******* ******** ******* *******
> ******* ***
> *   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!?
Make a great connection at Yahoo! Personals.
http://personals.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 
******* ****** ****** ****** ******* ****** ****** ********