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Re: Rebar Grades

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To Mr. Thomas Hunt,

	I have a copy of Reinforced Concrete Design Handbook, Second Edition,
Copyright 1955 by American Concrete Institute which I had as a student
in the early 1960s.  This book has a number of tables for compressive
steel, T-beams and others with values for fs as follows: 16,000, 18,000,
20,000, 22,000, 24,000, 27,000, and 30,000.  This book deals entirely
with working stress analysis; the working stress was normally not more
than half of the yield stress.  Most of the problems illustrated in the
book used 20,000 as the values for fs.

	Hope this helps.

				Regards,

				H. Daryl Richardson

Pat Bachman wrote:
> 
> The AASHTO Manual For Condition Evaluation of Bridges, 1994 recommends the following in Section 6.6.2.3:
> 
> Unknown grade prior to 1954, Fy = 33 ksi
> Unknown grade after 1954, Fy = 40 ksi
> 
> If you can find anything on the plans indicating Fs used for design, you can be pretty sure that if:
> 
> Fs = 18 ksi, Fy = 33 ksi
> Fs = 20 ksi, Fy = 40 ksi
> Fs = 24 ksi, Fy = 60 ksi
> 
> As for area of square bars, I have found nothing to use except a calculated value based on provided dimension.
> 
> Good Luck, Patrick Bachman, P.E.
> 
> *** Original Message ***
> 
> I am working on rehabilitating a 1950 concrete seawater intake structure
> that was designed per the 1946 Uniform Building Code.  The drawings call
> out for either 2500 psi or 3000 psi concrete and the rebar is called out as
> either square bar for deformed round bars.  Does any know what rebar grades
> were used in this time period?  I know 40 ksi rebar has been around for a
> long time but as grey as my hair is this is before my time.  I might add
> that this structure is in amazingly good shape with little deterioration.
> Goodos for our fathers and grandfathers.
> 
> Thomas Hunt, S.E.
> Duke/Fluor Daniel
>