MINIMUM REINFORCEMENT REQUIRED FOR CONCRETE BEAMS WITH HYBRID BARS AND HYBRID FIBERS-NUMERICAL INVESTIGATION

Abstract

The intent of this research is to establish a design procedure and formulate equations for a novel construction material. Adhering to design codes, one crucial requirement is to verify the minimum reinforcement area to ensure the ductile failure of RC members and mitigate crack formation resulting from shrinkage. Within this study, the authors explore the minimum reinforcement of beams with both hybrid bars and hybrid fibers through the utilization of numerical simulations. To analyze the flexural behavior of low reinforcement ratio members, fifteen RC beams are modeled and subjected to four-point loading configurations. The parameters under scrutiny encompass the hybrid reinforcement ratios ranging from 0.0% to 0.50%, as well as the beam depth. The outcomes of the numerical analysis, obtained through the Nonlinear Finite Element Analysis (NLFEA) method, are presented in light of maximum deflection, and cracking and peak capacity. Two distinct approaches are employed to explore the minimum reinforcement ratios: (a) the cracking moment approach and (b) the Ductility Index (DI) approach. Comparative evaluations between these approaches demonstrate that the incorporation of hybrid fibers allows for a reduction in the minimum reinforcement ratio. Specifically, when implementing the DI approach, the minimum reinforcement ratio decreases to 0.081% instead of 0.18% for RC beams. Notably, the DI approach exhibits superior agreement with the NLFEA results in comparison to the cracking moment approach.