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Re: 60,000 psi limit on Reinforceing bars

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Dear Michael,

Thank you for your response. I have a follow up question.
1. Using higher strength concrete would increse bond srength would it not?
2. Is not posssible or practical to manufacture 100,000 psi or more
reinforcing steel with  adequte ductility as required by code.

I agree with you on the possible brittle failure of high strength steel.

Thanks again. I hope you have a nice week a head

Alex C. Nacionales, C.E.
A.C. Nacionales Construction
Iloilo City, Philippines

-----Original Message-----
From: Michael Valley <mtv(--nospam--at)skilling.com>
To: seaoc(--nospam--at)seaoc.org <seaoc(--nospam--at)seaoc.org>
Date: Tuesday, June 23, 1998 3:06 PM
Subject: Re: 60,000 psi limit on Reinforceing bars


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