A Comparative Study on Column-Beam Dimensions and Reinforcement Percentages across Different Seismic Zones in Bangladesh

Abstract

According to, the Bangladesh National Building Code (BNBC 2020) divides the country into four seismic zones based on seismic risk levels. This study evaluates the structural response of an 8-story reinforced concrete building across these zones, focusing on the final beam and column section sizes and the required reinforcement percentages. The analysis uses the Equivalent Lateral Force (ELF) procedure, with earthquake, wind, and gravity loads assigned according to BNBC 2020 guidelines. Structural modeling and design are carried out in ETABS based on American Concrete Institute code provisions under a Special Moment Resisting Frame (SMRF) system. Service conditions are checked using property modifiers defined in BNBC 2020 to evaluate story drift limitations, sway, soft story effects, and torsional irregularity. Ultimate strength checks are performed using ACI 318-11 property modifiers. The final section sizes are selected after ensuring that beam-column capacity ratios satisfy both service and ultimate requirements. The comparative results show that structures in Seismic Zone 4 require the highest reinforcement and largest section dimensions, followed by Zones 3, 2, and 1.