A high rise building has to be designed to resist lateral loads due to wind or earthquake. Interior structural system or exterior structural system provides the lateral load resistance to the structure. The shape, structure and material used also influence the behaviour of structure against lateral loading. In this study three dimensional analytical models of G+12 storied buildings have been generated for regular and irregular buildings and analysed using CSI ETABS software (2015 version) for earthquake zone III in India. The objective of the project is to carry out seismic analysis (RSA) of regular and irregular reinforced concrete buildings and to carry out the ductility based design using IS 13920. Results of this analysis are discussed in terms of story displacements, story drifts, story shear and stiffness. From the results it is concluded that story displacements increases linearly with height of the building; maximum storey drift is observed at second floor for irregular structure and at fourth floor for regular structure; maximum storey shear force was observed between ground floor and second floor for regular structure and at ground floor for irregular structure and the value decreases linearly with height; storey stiffness varies non - linearly for both the structures with maximum values at ground floor. © IAEME Publication.