Hi Martymm...on most (or all) of our projects we model the fixed supports as rigid. However, we have done some alternate models where we include a structure, or equivalent structural stiffness, and the results can be quite different - sometimes it can result in pump nozzles, etc. being shown as overloaded.

As SHR has mentioned, if you use a specified stiffness for one support, you need to specify stiffness for all support on the system, or your results might be skewed.

Regards,

Pervez