Hi all,

I am using ISO 14692 to analyse a composite system.
I am wondering why allowable stresses for SUS (W+P) and SUS+Settlement (W+P+D) cases are different?

I'd appreciate if anyone can help.

This Code checks two stresses - hoop and axial. The program displays the stress with the largest stress-to-allowable ratio. Also, the allowable stresses may change as load changes.

Dave,

Thank you so much for your information.
However, in my case all loads are the same! I also double checked the load factors to make sure that for both SUS (W+P) and SUS+Settlement (W+P+D) , it is 1.0.

Is there any other reason for the difference in allowables or is there any other input that I might have entered wrongly?

Cheers

Is your allowable stress jumping to a much higher or much lower allowable? If so, I still believe the program may be listing a different check - going from axial stress controlling to hoop stress controlling. The limit for hoop stress is the hoop allowable while the limit for axial (bending) stress is based on total allowed axial stress at the current hoop pressure minus the axial stress due to pressure.

I have no other guesses to offer without more information about your model.

Dave,

Thanks for for the informative explanation.

In my model the allowable for SUS+Settlement (W+P+D) is 1.3 times of the allowable for SUS (W+P). I do not consider it much higher or much lower, it's like a normal factor which I do not know where it comes from.

This model is a combination of under ground FRP lines connecting to Carbon steel above ground lines attached to Tank nozzles.

If you need more detail information please let me know.

Thanks

Check the allowable stress multipliers in the Load Case Options. Adding a strain-based load (along with your stress type - SUS v OPE) to your load case may trigger a different allowable limit in accordance with ISO14692.