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RE: QUERY: How do you determine fpy?

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On Thu, 04 Jan 1996 22:48:33 -0600  Bill Polhemus wrote:
>Hello, all.
>
>I am extremely rusty when it comes to prestressed concrete design.  In 
>fact, it's been about ten years since I did anything with it.  Now I find 
>I have some evaluation of existing prestressed concrete structure to do, 
>and I'm trying to get back up to speed.
>
>The ACI 318 code, Chapter 18, makes reference to the value fpy, which is 
>the specified minimum YIELD strength for prestressing steel.  This is 
>analogous to fy, for mild steel reinforcing.
>
>However, I can't find anything in the smattering of references that I have
>that tells you how to estimate this value, even though it is used in a few
>"checks" in the design equations.
>
>Most of the design equations use fpu (Ultimate Strength), fse (residual 
>stress after losses), and fps (stress at service load).  Nothing about 
>fpy.
>
>Anyone have a clue?

fpu is a quantity that you would need to get from the 'as-built' drawings or specifications for the 
structure.  It's a characteristic of the steel used in the prestressing.

Nigel

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Nigel Mends, PE
email:  nmends(--nospam--at)mt.net
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