There are 3 major fault lines in our country, which are exposed to thousands of earthquakes every year, namely the North Anatolian Fault Zone and the East Anatolian Fault Zone. Therefore, earthquake effects are more important in terms of the structural behavior of the buildings built in our country. It is very important for building safety to design buildings as regularly as possible during the design phase. However, sometimes this is not possible for reasons such as architectural designs. In the study, 6 different models with the irregularity type of A3-Existence of Projections in the Plane and the symmetric reference model were analyzed according to Mode Superposition Method. The models analyzed in the study were modeled with the SAP2000 program. As a result of the analysis, the interstory drift performances of the models under the effect of earthquakes were examined. Comparisons were made in line with the results obtained from the analyzes and comments were made on the effect of structures with A3 irregularity type on the interstory drifts.