From: SGE Structural [mailto:sgordin@sgeconsulting.com]
Sent: Thursday, November 13, 2008 9:31 AM
To: seaint@seaint.org
Subject: STRESS AND FORCE
Struggling through the 2007 AASHTO BDS, I fail to understand one very basic thing. There was a good thing invented once, called stress, why the new codes use forces instead?
The use of forces - as those of resistance or loading - is so less informative, and does not give the same feel for the performance of material/component.
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Stresses are actually not a good indicator of failure. Factor of safety based on stresses are over-simplification. Question arises which stress you want to use a indicator? Principal stresses, Von Mises stress, or stresses based on several other hypothesis? Or, should we carry the whole state of stress in a form of stress vector and compare with the unknown "allowable stresses"?
-Suresh Acharya, S.E.
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Of course, all new equations allow conversion into stress, but why the change?
V. Steve Gordin, SE
Irvine CA
Irvine CA