Comparative Structural Analysis of Conventional Beam-Slab System and Flat Slab with Drop Panels Using ETABS

Abstract

The choice of floor system strongly affects the structural efficiency, clear headroom, and construction economy of multi-storey buildings. The conventional beam-slab system is stiff but limits architectural flexibility and the routing of services, whereas flat slabs remove the beams and speed up construction but are prone to larger deflections, which drop panels around the columns are used to reduce. This paper compares a conventional beam-slab system with a flat slab with drop panels in a 10-storey residential building modeled in ETABS. Both models have identical geometry (20.0 m × 20.0 m plan, 5.0 m grid, 3.0 m storey height), materials (f′c = 25 MPa, fy = 500 MPa), column sizes, loads, and supports, and were analyzed under gravity loading. The maximum vertical deflection at the critical top-floor mid-span fell from −6.00 mm in the beam-slab model to −4.10 mm in the flat slab model, a reduction of about 31.7%. The total dead load base reaction was 30,093.44 kN for the beam-slab model and 29,031.44 kN for the flat slab model (3.53% lower), while the live load reaction was identical at 12,000.00 kN. The results indicate that drop panels can provide adequate serviceability without down stand beams under the gravity loading considered. The findings may help engineers select a suitable floor system, although lateral loading, punching shear, and cost were outside the scope of this study.