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Re: WWII Allowable Structural and Reinforcing Steel Stresses

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Frank,

I am not sure about specific war time criteria but you may find some useful information in the following documents:

1.  CRSI Engineering Data Report #48.  This shows all the various types and strength values for rebar used in the U.S. from 1911 to present.  I believe you can download it free from the CRSI web site.

2. "The Mysterious 1/3 Stress Increase" by Duane Ellifritt.  This article chronicals the development of stress increase factors going back to the mid 1800's to present.  I can not remember where I downloaded this from but a search on the web may find it.  My guess is that it is from the AISC Journal.

Thomas Hunt, S.E.
ABS Consulting




"Hartzell, Frank" <Frank.Hartzell(--nospam--at)jacobs.com>

08/21/2003 10:10 AM

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WWII Allowable Structural and Reinforcing Steel Stresses





I'm pretty long in the tooth but didn't study structural engineering until just after the war. I am aware that the allowable structural steel stress was increased for structures built during the war but am not sure about reinforcing steel. I seem to remember that the allowable increase for structural shapes was about 25%.

I'm currently looking at modifying a building built in 1945 and am finding that the footing reinforcing steel is rather severely overstressed. The drawings call for deformed structural grade reinforcing steel which I believe would be 40 ksi yield with an allowable tensile stress of 18 ksi according to the codes of the period. I'm also assuming that the structural steel is the old A7, 33 ksi yield.

The drawings call for 13-3/8 bars each way in a 7 ft square footing which results in a steel ratio of only 0.0015, lower I think than even codes at that time permitted. It also seems rather odd to use No 3 bars in a footing but perhaps wartime shortages resulted in all sorts of unusual choices. It's also possible that the draftsman used 3/8 when he meant to use 5/8.

I intend to call for field investigation but, in the meantime, I was wondering if any old timers (or better informed engineers of any age) could enlighten me on the wartime design criteria.

Thanks for any help.

Frank Hartzell
Jacobs Engineering

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