Flexural Behavior and Failure Mechanisms of High-Strength Coral Aggregate Concrete Beams: Effects of Reinforcement Configuration and Loading Protocol

ABSTRACT This study investigated the flexural behavior of high-strength coral aggregate concrete beams with varying reinforcement configurations and under monotonic and multistage amplitude escalation loading. Four-point bending tests were conducted to evaluate the effects of reinforcement specimen on bearing capacity, crack development, and failure mechanisms. Critical mechanical responses, including specifically moment–displacement correlations, longitudinal bar strain profiles, and crack propagation behavior were quantitatively tracked throughout the loading sequence. Results demonstrated that increasing the reinforcement ratio significantly enhanced both the ultimate bending moment (Mut) and the cracking-to-ultimate moment ratio (Mcrt/Mut). The specimen reinforced with steel fiber-reinforced polymer composite bars exhibited superior ductility, wider crack spacing, and more distributed cracks compared to the conventional steel-reinforced specimens. Under multistage amplitude escalation loading, premature stress redistribution within the coral aggregates led to reduced structural performance, characterized by accelerated crack width expansion and earlier failure. The finite element analysis demonstrated good agreement with the experimental results in terms of bearing capacity, moment–curvature curves, load–strain curves, and damage distribution patterns, with additional parametric simulations conducted to extend the investigation beyond the tested configurations.