The following is the answer to your question on how STAAD genertaes the notional load:
1. Since notional loads are derived from gravity loads, the first step is in determining the lumped weight at the various nodes of the structure from the corresponding gravity loads. For example, when you declare the notional load as “1 X 0.002”, the program first generates the vertical weights (in the global Y direction) at all the nodes of the structure from the loading data you specified in case 1.
2. Once the nodal weights are obtained, those are then multiplied by the notional load factor, and the resulting value is applied along the direction that you want the notional load to act in. In this example, the vertical weights lumped at the nodes are multiplied by 0.002, and the results are then applied at the same respective locations along the global X direction.
If you want to obtain a report of the notional loads that the program generates, use the PRINT LOAD DATA option with your analysis command. For example,
PERFORM DIRECT ANALYSIS PRINT LOAD DATA
I notice that you are using version 20.07.05.15. I would suggest you to use the latest 20.07.06.34, which has some corrections regarding the Direct Analysis.
Sudip Narayan Choudhury