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Re: 60,000 psi limit on Reinforceing bars

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The Code imposes the same limit on yield strength for reinforcement 
(in seismic applications) regardless of the concrete compression 
strength.  Again, the concern is assuring ductile response.  There 
are at least two potential ductility problems with higher strength 
reinforcement:
1) The wrong limit state (bond failure) controls.
2) The reinforcing steel lacks adequate ductility at the material 
level.  This is why material satifying ASTM A706 or A615 (with 
additional requirements) is specified in the Code.

Internationally, some have used LOWER strength reinforcement to 
acheive higher levels of ductility in R/C response.

On Sat, 20 Jun 1998 13:04:50, Alex Nacionales wrote:
> What if  I  use 5000 psi or even 7000 psi
> concrete?
> 
> Alex C. Nacionales, C.E.
> 
> 
> Michael Valley wrote:
> 
> > On Thu, 18 Jun 1998 04:47:18, Alex C.
> > Nacionales wrote:
> > > I do not understand the 60,000 psi  yield
> > point
> > > limit on the concrete  reinforcing bars.
> > > Can some please give me a reason for this.
> > > Some bars tested on my projects reached more
> >
> > > than 60,000 psi  before it yielded.
> >
> > ACI 318-95 allows higher yield reinforcement
> > (for non-seismic
> > applications) per 3.5.3.2.
> >
> > The commentary to ACI 318-95 section 21.2.5
> > explains why the yield
> > stress is limited for seismic applications.
> > The concerns center on
> > the potential for limit states controlled by
> > shear or bond failure.
> >
> > - - - - - - - - - - - - - - - - - - - - - - -
> > - - - - - - - - - - - - - -
> > Michael
> > Valley
> > E-mail: mtv(--nospam--at)skilling.com
> > Skilling Ward Magnusson Barkshire
> > Inc.                  Tel:(206)292-1200
> > 1301 Fifth Ave, #3200,  Seattle  WA
> > 98101-2699          Fax:        -1201
> >
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> 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Michael Valley                                   E-mail: mtv(--nospam--at)skilling.com
Skilling Ward Magnusson Barkshire Inc.                  Tel:(206)292-1200
1301 Fifth Ave, #3200,  Seattle  WA 98101-2699          Fax:        -1201