Behavior and strength of hidden Rc beams embedded in slabs

Abstract

Reinforced concrete (RC) beams protrude from the ceiling, unless there is an infill wall beneath. Sometimes the construction of these beams is avoided due to aesthetic concerns, and instead a reinforcement arrangement with an equivalent bending moment capacity in the slab is made; this is named as a hidden beam. However, since such a design based only on strength can change the behavior to a great extent, the drawbacks of hidden beams were experimentally investigated. A total of fourteen half-scale specimens, including conventional T-beams and slabs with identical flexural capacities (hidden beams), were tested to failure under four-point loading. Reinforcement ratio and slab thickness were adopted as test parameters. The results indicated that hidden beams were able to achieve reference strengths after excessive (up to eight times larger) deformations, or they occasionally could never achieve these capacities. Experimental data were also compared with analytical deflection approaches.