Performance of a Steel Fiber Reinforced Concrete Deep Beam with an Opening: A Non-linear Finite Element Analysis

Opening in RC deep beams is often necessary to provide utilities with a passage through the beam, while the beam itself should be capable of sustaining high stress as a transfer beam. The presence of an opening in the beam will create stress concentration that eventually reduces its strength and stiffness. The conventional way to cope with this situation is to provide shear reinforcement that resists the tensile stress when the concrete cracks. One of the major drawbacks is that the concrete would have to crack first to redistribute the tensile stress from the concrete to the shear reinforcement. Another alternative proposed in this paper is to use steel fiber, which not only resists crack growth but also increases the tensile strength of concrete. The proposed solution is evaluated using an in-house finite element analysis package. The stress–strain model for the steel fiber reinforced concrete under tension was adapted from the author's previous work using the superposition method and calibrated with the laboratory test results. The crack propagation for plain reinforced concrete (RC) and steel fiber RC deep beams were compared and discussed. From the analysis, using steel fiber effectively increased the load-carrying capacity of the deep beam.