1) The NUREG jobs are dynamic benchmarks only - there is no static analysis for these jobs.

2) The support stiffnesses are provided in the NUREG bulletins.

3) Think about piping supported on the ground, then the 1st level of a rack, and also the 2nd level of a rack. The seismic activity excites the supports on the ground. Some of these supports will be pipe supports, others will be the rack supports. As the rack is excited, the supports on the 1st and 2nd level will also be excited, but differently from the ground and from each other. In this example, there would be three support groups. Note though, these other spectra were also provided in the NUREG bulletin - usually you would obtain this information from your Structural group. Alternatively you can model the rack and let CAESAR II do all the work.

4) This is the acceleration of gravity in "in/sec2".

5) This is also an input defined in the NUREG bulletin.

6) The frequency extraction stops at either: the cut-off value you specify, or the number of frequencies you specify. Typically you would use a cut-off value since you don't know how many frequencies exist below any certain value. In this benchmark example, the NUREG bulletin specified the number of frequencies to extract.

You don't need a referenced static load case unless the job is non-linear (has non-linear supports like +Ys, gaps, or friction).

A response spectrum analysis always begins with the natural frequency extraction.