Comparative Cost and Design of Solid, Ribbed and Waffle Slab for a Three-storey Shopping Complex Using Prota, Orion and Spreadsheet

Cost is an important factor in choosing the type of floor or slab used in any construction. When a large space within a building needs to be covered without hindrance and supports, waffle or ribbed slabs are used. For all slab systems, the cost constitutes a significant portion of the overall cost of the structure. Therefore, this research aims to select a preferable slab system with the least construction cost for a shopping mall. Computer-aided design software such as Prota 2018 and Orion 2018 was used for analysis and design, and RCC spreadsheets were used to manually check the slabs. The results reveal that the Solid floor slab has more concrete volume and steel than the waffle, and the rib consumes the lowest least volume of concrete and steel among the three slab systems. Therefore, the rib slab is the most economical of the three slab systems since it uses the least concrete and reinforcement. The cost of a floor slab system ranges from 12 to 17% of the structural cost in building works, the percentages of the cost of the slab in a floor system is 17.84% for solid slabs system, 13.65% for rib slabs and 12.48% for waffle slabs of the total cost of a structure. It can therefore be concluded that using rib slab saves 17.95% and 7.46% of the construction sum when compared to solid slab and waffle slab construction systems respectively. In conclusion, it is recommended that ribbed slabs should be used for commercial building construction with more than 5KN/m2 live load in commercial buildings that spans up to 15m and more.