Comparative Assessment of Reinforced Concrete Slab Systems for Office Buildings in Kuwait

The selection of a reinforced concrete slab system influences structural efficiency, cost, embodied carbon, and serviceability. Six cast-in-place slab systems were compared for a four-story office building in Kuwait with 6- and 9-meter spans to determine which system provides the best overall performance.

Twelve CSI ETABS models were developed. Loads were specified in accordance with ASCE 7-16, and reinforced concrete design was in accordance with ACI 318-19. Evaluated parameters included concrete and reinforcement quantities, direct material cost, embodied CO₂ emissions, structural weight, vertical natural frequency, and X-direction seismic displacement. An MCDM method was used to rank the alternatives, with deflection, punching shear, and story drift assessed separately.

The flat slab with drop panels (Design 5) achieved the highest ranking at both spans, with MCDM scores of 0.989 and 0.993. This system resulted in the lowest cost, embodied CO₂ emissions, structural weight, and X-direction displacement. At a 9-meter span, Design 5 reduced cost and CO₂ emissions by 6.4% and 7.3%, respectively, compared to the next-best alternative.

The results indicate that maximizing stiffness does not always yield the most efficient structural solution. Targeted strengthening at column zones can enhance performance without incurring the material costs associated with continuous beams.

For similar office buildings in Kuwait, Design 5 provides the optimal balance of economy, sustainability, structural efficiency, and serviceability, pending project-specific verification.