Investigation of Flexural Behavior of Voided and Crosstie Reinforced Slabs

Abstract

Reinforced concrete slabs constitute a significant portion of the building weight. One of the methods developed to reduce the slab weight is the voided slab system. In this system, voids are formed with materials such as plastic or foam. In this study, voided slabs with concrete connections, which are rarely found in the literature, were investigated. Because there is no sufficient study regarding the bending capacity and behavior of voided slabs, 11 slabs with varying void ratios and crosstie reinforcement were tested to fill this gap. In this context, three solid slabs without voids and eight slabs with different void ratios were produced. Polystyrene foam was used to create three equal layers. The top and bottom layers are reinforced concrete, and the middle layer consists of square concrete connections and polystyrene foam, which has not been studied yet. The slabs were divided into two groups: the first group specimens had no crossties, whereas the second group had varying crossties. In this context, it was tried to determine the optimum weight and performance of the slab. A uniformly distributed load was applied using the three-point bending method. According to the results, the slab weakened with the use of polystyrene foams, and the ultimate load capacity decreased accordingly. The stiffness, ductility, toughness, and load capacity of solid slabs were found to be higher than those of voided slabs. When the void ratio was 20%, the failure mode changed from flexure to shear. By using crosstie reinforcement, shear failure was prevented, and ductile behavior was increased. Finally, the load capacity of the slabs was compared with ACI318-19 and other studies, and a new equation was proposed.