From recent earthquakes it is proved that many of structure are totally or partially damaged due to earthquake. So, it is necessary to determine seismic responses of such buildings. Also presence of mass irregularity in the structure may lead structure to the failure if not taken into account. There are different techniques of analysis of structure. Response spectrum analysis is one of the important dynamic methods of analysis which will be used in this project work. This paper is concerned with the effects of various Mass and column stiffness Irregularity on the seismic response of a structure. The primary objective of the project is to carry out Response spectrum analysis (RSA) of vertically Mass irregular RC frames with column stiffness variation. Comparison of the results of analysis of irregular structures with regular structure will be done. Comparison of mass irregular buildings having different column stiffness will also be done. The scope of the project also includes the evaluation of response of structures for axial force, base shear, time period, storey drift and storey displacement.

Keywords : Mass irregularities, Column Stiffness, Seismic Analysis, response spectrum analysis, Base Shear, Drift, Displacement.