Div-1-UG-23(b)-Allowable Compressive Stress

What! more homework?? Why would you want to know the allowable stress on a vessel that you are going to pressurize? especially if you're standing next to it!!

Good one!..lol

Not familiar with Jawad and Farr Guidebook, but reference to this is the only clue that you're talking about pressure vessels, not structural members. Can't comment on point A etc, but for elastic modulus as usually understood it's the same for tension as compression, in the elastic range.

However, for members under compression or vessels under external pressure, the load is usually limited by elastic instability (buckling) rather than allowable stress. For example, a vessel designed for full vacuum is typically good for several bar internal pressure (actual figure depending on vessel details)

Jawad! He is a great guy, I studied under him for a while. Great teacher, and very knowledgeable, one of the top guys in pressure vessels in the country.

I still don't understand "its value comes to half of the actual value of E under tensile loading conditions)". What is "a curve for a material in external pressure chart"? Maybe if I had the book in front of me it would be clear, but your stress-strain curve (though very nice!) doesn't explain it (not to me anyway). In the elastic range, for compressive stress it would be same slope but negative strain.

BTW is there any other way of measuring E except by using the slope between 2 points on elastic portion of a stress-strain curve?

The modules of elasticity E is considered as a physical property of a material, and that figure of E is fixed at certain temperature and reduced with higher temperatures. And that figure of E is used in analysis and/or calculations whatever the exercise is tensile or compressive.

See the attached Table TM-1 of ASME VIII-1 showing the Moduli of Elasticity E of ferrous materials for a given temperature.

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