Hi everybody,

im relatively new in Caesar II-calculation (since 1,5 year). I have the following 2 questions/remarks concerning spring hanger design in Caesar II, these facts are based on Caesar II 5.3 and were tested and confirmed under the 7-Version (2014).

-Spring Design in Caesar II 1(assuming a linear system without friction) begins with the 1-HGR load case, which in fact determine the needed reaction load of a rigid restraint at the wished spring location due to weights loads. The calculated force is then put as constant force at that location while system is subjected to the design operating temperature to determine the spring displacement this load case is 2-HGR. Knowing the spring force and the displacement at operating condition, installation load is calculated. The calculated installation load is then put as external load for combination with other loads. We consider its combination with the design operating temperature and weight and pressure-for which the spring is designed- as OPE-load case. It s expected in linear analysis to have the same displacements and loads at the spring node for the load cases 2-HGR and OPE, what is well the case in Caesar II calculations. But this is in Caesar II only then the case when the E-Modulus is the same for 1-HGR and 2-HGR, this is what i could not understand.

I have collected the results in Excel-sheet, that i can share with the
program file i needed. In the sheet i compared many possibilities to show this and i mentioned the problems.

The second problem is the friction effects in 1-HGR, they seem to be not considered in this load case although the friction multiplier is set to 1 in load case editor for this load case. Generally it can be neglected since in weight load case friction generally has no big influence, but in some cases friction affects considerably the restraint loads in weight-load case as well. I can share Excel-sheet and the program-file if needed.

Appreciate your support in advance.

Ali.

Not necessarily, case #2 does not include the spring stiffness, since the spring hasn't been selected yet. Case #3 does have the spring stiffness, in addition to the preload from case #2. This is why you "may" see different results between cases 2 and 3.

For your friction question, do you have a CAESAR II model where friction affects case #1?

Hi Richard,

thank you for answering. In a linear analysis, Case#2 and case#3 would produce exactly the same displacements and it is in fact the case in Caesar II. The problem for me is only in case, in which different E-modulus are used in the cases (1-HGR and 2-HGR), in this case the displacement in case 2 is multiplied with the E-modulus ratio (it's tested by me by using many E-modulus combinations). I think its an algorithm matter since CAESAR is mainly designed for ASME-code which states the use of EC in all cases. In case of friction, the cases may differ of course (the friction of a displacement dependent load is different from the friction of constant load), here i don't have problems with Caesar II-results.

for the second question i posed, here are the files

Friendly greetings,
Ali.

Attachment is below.

Ali.

Please open a Support Request on Smart Support and send in the job files, so that Tech Support can evaluate and advise.