quoting "Steel Structures" 2nd ed., by Salmon & Johnson, p41-42:
"Stress-strain curves show a straight line relationship up to a point known
as the proportional limit, which essentially coincides with the yield point
for most structural steels with yield points not exceeding 65 ksi. For the
quenched and tempered low alloy steels the deviation from a straight line
occurs gradually. Since the term yield point is not appropriate [for these
steels], yield strength is used, [defined as] the stress at an offset strain
of 0.2%; or alternatively, a 0.5% extension under load."
Hope this helps.
From: "Fountain Conner" <fconner(--nospam--at)pcola.gulf.net>
Subject: RECAP -- Re: Proportional Limit, A36 Plate
The more I learn, the less I know...
Suggested range of Fp is between 70 percent and 100 percent of Fy. If we
were voting, the 100 percent figure would be in the lead (I found a couple
more references). But you all have your suspicions about how votes are
dealt with in Florida ;-)
Charlie Carter pointed out that I'm likely to have A-36 steel with a yield
significantly higher that 36ksi. Good!
Charlie also noted we weren't likely to get into the range of yield in this
design. Agreed, but the variation of Fp has almost a one-to-one
relationship to the allowable bending stress in the shell. With the
geometry of this stack, Fp 30 percent below Fy (from Neil Moore), reduces
allowable bending stress by about 28 percent, nearly a one-to-one
I'm not comfortable with this much variation.
* This email was sent to you via Structural Engineers
* Association of Southern California (SEAOSC) server. To
* subscribe (no fee) or UnSubscribe, please go to:
* Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you
* send to the list is public domain and may be re-posted
* without your permission. Make sure you visit our web
* site at: http://www.seaint.org