I need to say to design RC frame structure for seismic region instead of designing and analysis of all body of structure which part of structure I have to care out in design to resist seismic resistance
Basically you have to analyze the whole structure for seismic load and reinforcement detailing of beam-column joints and RCC bands/slab is very important. Also based on the calculated base shear, foundation is to be designed appropriately.
I think that you should try an analysis with plastic hinges and find the critical collapse mechanism. From the results you should be able to define which parts of the structure have to care out in design. But in general the most critical areas are as mentioned above the beam column joints and the columns.