Nonlinear Analysis of Steel Moment-Resisting Frames for Evaluating Ductility Ratio

Abstract

This study investigates the seismic performance of composite flat slab and grid slab structures, emphasizing their behaviour under earthquake loading conditions. The analysis focuses on tall and slender buildings (L/B > 4, slenderness ratio = 2.88) without infill elements, revealing their unsuitability for seismic-prone regions due to reduced lateral stability. Buildings with an aspect ratio greater than 3 experience higher base shear in both directions, despite a lower seismic weight, whereas square plan buildings (aspect ratio = 1) demonstrate superior seismic resistance due to evenly distributed base shear forces and reduced fundamental periods. The findings highlight that incorporating drop panels increases the fundamental frequency by 20%, while grid slabs enhance structural stiffness by up to 96%, significantly improving lateral stability. The introduction of column drops further reduces storey displacement and mitigates punching shear forces by 25%, enhancing overall structural performance. The study underscores the importance of structural modifications in improving seismic resilience. Future research should focus on the integration of infill walls, bracing elements, and advanced reinforcement techniques to enhance energy dissipation, reduce structural vulnerabilities, and ensure the safety and durability of high-rise buildings in seismic regions.