Experimental investigation on structural behavior of composite slabs with steel decking, fiber-reinforced concrete, and lightweight aggregate concrete layers.

This study experimentally investigates the structural behavior of steel-concrete composite slabs under monotonic loading, with a focus on evaluating the influence of fiber content, fiber types, layer arrangement, and screw density on their performance. Twelve composite slabs, consisting of two layers of lightweight aggregate concrete (LWAC) and fiber-reinforced concrete (FRC) cast on steel decking, were fabricated and subjected to four-point bending tests. Experimental variables included fiber volumes (0.1%, 0.3%, 0.5%), fiber types (steel, polypropylene, or hybrid steel‒polypropylene), shear connector types (screws, end shear studs), screw spacings (200 mm, 300 mm), and layer arrangement. The results showed that increasing the fiber content significantly enhanced load resistance, reduced end slip, and improved strain capacity. Specifically, slabs with 0.5% fiber content achieved a 155% higher load capacity compared to those with 0.1%. Placing fiber-reinforced concrete (FRC) in the bottom layer and lightweight aggregate concrete (LWAC) on top provided better composite action, optimizing the performance of all components. Screw connectors greatly improved shear bond resistance and flexural strength, with slabs using 200 mm screw spacing showing 2.6 times higher strength than those without screws. Compared to traditional steel-concrete composite slabs, screw reinforcement increased flexural strength by up to 164%. The combination of FRC and screws led to favorable failure modes, such as distributed flexural and shear cracking with slip, which effectively utilized the full material capacity.