Included mass data in response spectrum analysis

Already many users might have asked this question and hence request administrator to provide links on this topic which will clear following doubts:-
1. "Active force" in output to be in the range > 65-70 % for each of the directions X,Y,Z- Is my understanding correct ?
2. "Added force" in output to be in the range of 25 - 35 %- Is it OK ?

Are there any guidelines based on experience of dynamic analysis users to get better mass participation in above report ) Included mass data)
. Regards,
bagpiper

1) Follow the rules of thumb for node spacing:
- element lengths no more than 1-foot per inch of diameter
- at least one node between each elbow, restraint, tee, or rigid

2) Make sure you're using the "missing mass" option

3) Extend the frequency cut-off (unless you've already done that).