Prestressed Beam Material Properties for 1961 Project

Guastavino · Jul 9, 2015

Hi all,

Anyone know of a good location to find historic prestressed values for specifically f'c and fpu? Below is a beam sketch. I've looked online and I have a 1st edition PCI design handbook but it only goes back to 1971. It's on my list to buy historic ACI 318, but I haven't got around to it yet. I've scoured the original drawings for a note defining f'c and fpu and there is none to be found. Not even design loads, which isn't all that uncommon for a 1961 structure, but I was hoping for at least something. Anyone experienced structures of that age. Project location is North Carolina.

Thanks,

Nick

hokie66 · Jul 9, 2015

I don't think much has changed. My textbook by Dunham from 1964 lists the strands as 250 ksi, with forces initial 18.9 kips, transfer 18.0 kips, and final 15.1 kips. I think the most common concrete strength for precast members was 5000 psi, but 4000 psi would be a conservative guess in the lieu of testing. The #3 bars would be Grade 40.

Guastavino · Jul 9, 2015

Thank you Hokie. I really appreciate it.

Guastavino · Jul 9, 2015

Hey Hokie,

Was the "final 15.1k" after the estimated losses? I get a similar value when I take 250ksi*0.106in^2*0.7*0.8=14.84k, which is 0.7*fpu with a then 0.80 lumped factor for losses. Thanks.

hokie66 · Jul 10, 2015

Yes, that was the design load after losses. I found the 15.1 kip value listed also in Winter's text, 1964 edition, and the values were attributed to John A Roebling's Sons Corporation.

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Prestressed Beam Material Properties for 1961 Project

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