Thank you for your reply
1)I tried all the load With a new manual combination created to be calculated as p-delta but I got the same issue.(no loads shown in the simple cases)
2)but if make the simple cases static linear and the load combination as p-delta, I'll get all the loads in the simple cases tab, but do robot in this case use any result (especially defection) from the p-delta combination.
what I mean, in ACI-318 we can use p-delta analysis and ignore the factors of moment of inertia for each member. Case (2) above can lead of the same results?
what about the new option in robot 2015 the DAM analysis? can i use it for concrete structure? Will it have any effects on base shear when designing the footing (if seismic load is added)