Analysis and Design of Flat Slabs Using Various International Design Codes: A Comparative Study

Flat slab systems have become one of the most preferred reinforced concrete floor systems for multistorey buildings due to their architectural flexibility, reduced construction time, improved aesthetics, and ease of installation of building services. Unlike conventional beam-supported slabs, flat slabs transfer gravity loads directly from the slab to the supporting columns without intermediate beams. Although this structural arrangement provides significant economic and architectural benefits, it also introduces critical challenges such as punching shear failure, excessive deflection, vibration, and stress concentration around slab–column connections. Therefore, the structural design of flat slabs requires careful evaluation using appropriate design methodologies and code provisions. Different international design standards, including IS 456:2000, ACI 318-19, Eurocode 2 (EN 1992-1-1), and BS 8110, provide different approaches for the analysis and design of flat slabs. These standards differ in the calculation of bending moments, punching shear resistance, serviceability criteria, reinforcement detailing, and load combinations. Consequently, identical structural systems designed according to different codes often result in varying slab thicknesses, reinforcement requirements, safety margins, and overall construction costs. This research presents a comprehensive comparative investigation of flat slab analysis and design using four internationally recognized reinforced concrete design codes. A prototype reinforced concrete multistorey building is analysed using the Direct Design Method (DDM), Equivalent Frame Method (EFM), and Finite Element Method (FEM). Structural responses such as bending moments, shear forces, slab deflections, punching shear stresses, reinforcement quantities, crack widths, and material consumption are evaluated and compared. The study also examines the economy, structural efficiency, and safety provisions of each design code. The results provide practical recommendations for structural engineers in selecting suitable design procedures for different building configurations.