I have a question regarding the way CAESAR calculates the allowable expansion stress. I am using B31.3 'liberal allowable', equation (1b) in the code book. The code states that Sh is the "basic allowable stress at maximum metal temperature expected during the displacement cycle under analysis." It appears though, that in certain cases CAESAR is using the maximum temperature that I enter for an element, regardless of which temperatures are involved with a particular load case.

For example, lets say that I have an element with three temperatures entered on the input spreadsheet for this particular element, T1=100, T2=400 and T3=1000, with corresponding Sh1=20,000, Sh2=20,000, and Sh3=5,000. The load cases in the file might be:

L1=SUSTAINED
L2=L1+T1
L3=L1+T2
L4=L1+T3
L5=L2-L1 (exp. code check 1)
L6=L3-L1 (exp. code check 2)
L7=L4-L1 (exp. code check 3)
L8=L3-L2 (exp. code check 4)
L9=L4-L2 (exp. code check 5)
L10=L4-L3 (exp. code check 6)

The numbers are not from a real problem, I just made them up for the example. It seems from the code that I should have 2 different allowable stress values for the 6 expansion stress ranges above, calculated using Sh=20,000 for L5, L6 and L8 and using Sh=5000 for L7, L9, and L10. When I run a file similar to the example above, CAESAR correctly calculates Sa for L5 and L6 based on Sh=20,000, but it is calculating Sa for L8 based on Sh=5,000 even though the maximum metal temperature on this particular element encountered during this displacement cycle is T2=400. I am thinking from the above statement from the code that L8 should be based on Sh at T=400, and I should be able to calculate a somewhat higher allowable stress range for this particular load case using Sh at T=400 in equation (1b). Is this correct?