The flexural behaviour of multi-layered steel fiber reinforced or ultra-high performance-normal concrete composite ground slabs

Residential and commercial buildings, racking legs from storage platforms, and other structures all depend on reinforced concrete ground slabs. Composite ground slabs composed of different layers of concrete are a novel subject of investigation and studies related to bending behavior of ground slabs are few. A twelve layered ground slabs (400 x 400 x 150 mm) was prepared in order to assess the flexural behavior with respect to cracking growth, cracking load, failure style, ultimate capacity, deformations, and load-settlement relation. The bottom tensile layer of the slab is made of steel fiber reinforced concrete (SFRC) or ultra-high performance concrete (UHPC) which comes in different thickness ratios of 0, 25, 50, and 75 %. The remaining top thickness of the slab is made of normal concrete (NC) to resist the compression force. In certain slabs, steel connectors spaced at different intervals were used to keep the layers from separating. The slab's deformations at the edge and in the middle were measured in relation to the applied load. The results indicated that the ultimate load of the ground slabs increased by 45.5, 56.5, 64.2 % and 72.7, 78.8, 86.2 %, respectively, when SFRC and UHPC were utilised to replace 25, 50, and 75 % of NC height. When 25 % of the NC-slab height was replaced with SFRC and UHPC, the carrying loads of the slabs rose by 100 and 162 %, respectively, at 1-2% settling. When compared to NC-slabs, all load-settlement characteristics in layered SFRC/UHPC slabs' center or edge deformations had shown a notable improvement. Using analytically indicated models, the ultimate capacity and settlements of ground slabs were anticipated. The experimental and theoretical results agreed.