GRE-dynamic analysis

just wonder to know if anyone has had the same problem while performing a dynamic analysis (time history) on a GRE system; do I need to manually compare the calculated stresses with the allowable stress? the allowable limit stress does not appear in the dynamic output.

If it is a surge or water hammer analysis, you can consider it as occasional allowable stress (ISO 14692 if this the code you are using).

Warm Regards,
Johnnel

You can set this in (Static/Dynamic Combinations) & select occasional.

D1+SUS(W+P1+H)

D1 -----> Dynamic Loads

SUS-----> Sustained Loads

Warm Regards,

Hi Borzki,

thanks for the reply,

I don't think there is anywhere in the dynamic module where one can set up the load case type. I thought all the dynamic calculations (except modal and harmonic) are (OCC) by default. I can only configure the combination method of the selected load cases (either SRSS or ABS)
and by the way, for the Iso code or the likes of it for GRE, I think the combination of OPE+D1 would be a more sound OCC load case.

Hi Pooria,

I haven't have experience regarding GRE dynamic analysis. As long as you have considered the dynamic effect & combined it with appropriate load cases and followed the Code allowable requirements you are in good shape.

Once I encounter this, I will try to deep dive & share with you how to tackle this using Caesar II.

Warm Regards,

up

The issue with GRE is that there's no single one way to analyze it statically - each manufacturer will (or should) provide you guidance with how to tabulate stresses statically.

I've had manufacturers tell me to treat it like metal piping, but with different allowable stresses for different cases.

I've also had manufacturers tell me to use GRE specific code.

So, without specific experience analyzing GRE dynamically, I'm hesitant to tell you that the dynamic output definitively matches that of the static analysis code, but I would have to believe that is the intent of the authors of the software.