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

Re: ACI Code requirement: ties at steel

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

I certainly did not develop this requirement, but here is an attempted
rationale for you.

Review ACI 7.9.1  Connections.  An elevated transition from a steel column
to a concrete column is basically a splice.  The anchor bolts are anchorage
for the steel column above.  Though not a direct bar to bar transfer, you
are relying on bearing at the top of the concrete column to accept the
forces from the steel column.  This transfer of compression requires
confinement.  If this was a slab or footing, confinement would be provided
by the surrounding concrete, and ties are not required unless you are
introducing moment and shear into the connection.   If you are introducing
moment and shear, you are most likely dealing with lateral forces, hence the
Chapter 21 requirements.

Refer also to ACI 15.8.3.3  Anchor bolts and mechanical connectors shall be
designed to reach their design strength prior to anchorage failure or
failure of the surrounding concrete.

Again this is consistent with what I indicated above.

I am in agreement with Roger, and my practice is similar.

Paul Feather
San Diego, CA

----- Original Message -----
From: "Keith Fix" <kefix(--nospam--at)yahoo.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Wednesday, June 06, 2001 6:26 PM
Subject: Re: ACI Code requirement: ties at steel


> This condition is where I've seen this tie arrangement detailed the most,
> however; the code requirement remains, and I accept the explanation
already
> given.
>
> That said, I would appreciate the opinion of someone who developed this
code
> requirement.
>
> -Keith Fix
>
> --- syed faiz ahmad <syedfaiz23(--nospam--at)hotmail.com> wrote:
> > Gentlemen
> > Ties around anchor bolts or hair pins around the same & developed into
> > slab-on-grade is meant to transfer horizontal force ( of the frame
reaction
> > ) to the soil rarther than for any other purpose. This response is
specially
> > directed to our learned friend Engr. Roger Turk.
> > SYED FAIZ AHMAD
> > SENIOR STRUCTURAL ENGINEER
> > SAUDI OGER LTD
> > RIYADH, SAUDI ARABIA.
> >
> >
> > >From: Tom.Hunt(--nospam--at)d-fd.com
> > >Reply-To: seaint(--nospam--at)seaint.org
> > >To: seaint(--nospam--at)seaint.org
> > >Subject: Re: ACI Code requirement: ties at steel
> > >Date: Wed, 6 Jun 2001 14:14:18 -0700
> > >
> > >Keith,
> > >
> > >The 97 UBC sections are 1921.4.4.8 and 1921.7.4 and it does not seem to
> > >appear in ACI 318.
> > >
> > >Thomas Hunt, S.E.
> > >Duke/Fluor Daniel
> > >
> > >----- Forwarded by Tom Hunt/DFD on 06/06/01 02:08 PM -----
> > >
> > >                     Keith Fix
> > >                     <kefix@yahoo.        To:     seaint(--nospam--at)seaint.org
> > >                     com>                 cc:     asherma(--nospam--at)c-b.com
> > >                                          Subject:     Re: ACI Code
> > >requirement: ties at steel
> > >                     06/06/01
> > >                     10:19 AM
> > >                     Please
> > >                     respond to
> > >                     seaint
> > >
> > >
> > >
> > >
> > >
> > >
> > >Thanks!  All this makes sense, but I've missed it these last 6+ years
(as
> > >have
> > >my previous employers).
> > >
> > >I also found the code references, with help from Mitch Sklar.  They
are:
> > >
> > >1996 BOCA 1913.1.3
> > >1997 SBC 1914.1.7
> > >
> > >I also noted the requirement for 9" embedment; I've used 8" in the past
and
> > >only switched to 12" in the last 2-3 years in conjuction with my
adoption
> > >of a
> > >1'-4" minimum footing thickness.
> > >
> > >Thanks to you both.  I am appropriately humbled.
> > >
> > >-Keith
> > >
> > >--- Roger Turk <73527.1356(--nospam--at)compuserve.com> wrote:
> > > > Keith,
> > > >
> > > > Yes, I design that way not only in concrete, but also in masonry
> > >whenever
> > > > anchor bolts are installed to support a concentrated load and
regardless
> > >of
> > > > the material used to transfer that concentrated load. The ties
provide
> > > > *confinement* to the concrete and increases its ability to take
> > >compressive
> > > > forces.  In masonry walls, I use hairpins around anchor bolts at
edges
> > >of
> > > > openings and ends of walls.
> > > >
> > > > A. Roger Turk, P.E.(Structural)
> > > > Tucson, Arizona
> > > >
> > > > Keith Fix wrote:
> > > >
> > > > . > But do you detail this way, and why?
> > > >
> > > > . > -Keith
> > > >
> > > > . > --- Roger Turk <73527.1356(--nospam--at)compuserve.com> wrote:
> > > >
> > > > > Keith,
> > > > >
> > > > > Good practice is not always codified.
> > > > >
> > > > > A. Roger Turk, P.E.(Structural)
> > > > > Tucson, Arizona
> > > > >
> > > > > Keith Fix wrote:
> > > > >
> > > > > . > I give up! I can't find it!
> > > > >
> > > > > . > My boss remebers a code requirement for ties around anchor
bolts
> > >for
> > > > > steel
> > > > > . > columns and/or at the tops of concrete pedestals for steel
> > >columns.
> > >We
> > > >
> > > > > . > have only been able to find the requirement in the earthquake
> > >section
> > > > of
> > > >
> > > > > . > UBC 97, but not for general loading or in any other code.
> > > > >
> > > > > . > If anyone knows where this code requirement can be found,
PLEASE
> > >REPLY!
> > > > >
> > > > > . > Also, your usual practice and engineering judgement is also
> > > > appreciated.
> > > > >
> > >
> > >
>
>
> __________________________________________________
> Do You Yahoo!?
> Get personalized email addresses from Yahoo! Mail - only $35
> a year!  http://personal.mail.yahoo.com/
>
> *
> *   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
>


* 
*   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