This document analyzes the seismic effects of rigid floor diaphragms in multi-storey reinforced concrete buildings. Eight building models are considered - with rigid and semi-rigid diaphragms, and with shear walls in the x-direction, y-direction, or both. The models are analyzed using ETABS software to determine time period, base shear, story drift, and maximum displacement. Results are compared to evaluate the impact of diaphragm type and shear walls on seismic response. Having rigid diaphragms and shear walls is found to reduce lateral displacement and drift compared to flexible or semi-rigid diaphragms without walls. The study aims to select the most economical design that provides comparable