A-36 Beams 2

[Eugenio9]

I'm calculating which measurements are necessary in order to sustain a load (tension) of 5 tons with the total length of the beam of 10 meters. But what I'm not sure is which allowable stresses should I consider. I found that the yield tensile strength is 36 ksi, but in the MDSolids programs its automatic value for A-36 is 21 ksi for tension, compression and shear, and I'm not sure why. Does anyone know if I should consider 21 ksi or 36 ksi?
Thank You.

 

[Eugenio9]

In reality the load will be smaller, I'm already giving it a margin in that area.

 

[SnTMan]

Eugenio9, per ASME pressure vessel Code data (Sec II, Part D) Sa-36 minimum yield strength is 36 ksi as you noted. Allowable tensile (for design) is 16.6 ksi up to 650 F. Again this is for ASME Code work only.

Your program's value of 21 ksi may be per a structural or some other Code. You are going to need to know what your software is doing.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[MJCronin]

How is this an ASME (mechanical) Code question ?

This sounds like a fundamental Structural engineering question and can be addressed by posting in the appropriate forum

MJCronin
Sr. Process Engineer

 

[Geoff13]

A common allowable tension stress is 0.6 Fy, which for A36 would be 0.6(36)=21.6 ksi. Suspiciously similar to the value you noted.

 

[Eugenio9]

Perfect, thanks for the help!

 

[JStephen]

In most cases, the allowable stress for an A36 beam would come a specific design code. And in most cases, that stress would vary depending on how the beam was laterally supported to prevent buckling, and in many cases, would be less than the 21ksi you mention. There are building codes, bridge codes, lifting beam codes, etc, and each has their own requirements.
Some of the codes are based on allowable stress, some on strength level, so don't confuse the two there.
Also, note that a lot of shapes formerly produced as A36 are now A992.
Where the program comes up with that stress- no clue, you'd need to ask the program publishers.