Development is a non-stop process it is seen that nowadays the development has reached to a new level. The development along with serviceability, durability, safety, innovation criteria in design etc. are lot more things to be concerned. The design approach has now gone so far in the field of advancement since, the complex multi-storey structures cannot be solved with ease manually the help of more detailed and dynamic analysis has helped to solve such structures with lots of plan and vertical irregularities. The different structures taken in this research are Irregular G+9 RC Frame Multi-storey building.The structure is irregular along the height possess vertical irregularity. The structure is considered to be in high seismic Zone V with damping ratio ( ) of 5%. The cases taken here is an irregular structure with step-up at storey-6 which is having fixed-base support is compared with the same irregular structure with step-up at storey-6 having base-isolation (LRB). The Dynamic analysis approach is used for the study of response of the structure and design by RSA (Response Spectrum Analysis). Keywords: Base-isolation damper, Frame structure, Irregularity, Response Spectrum Method