Structural Behaviour of Functionally Graded High-Strength Hybrid Fiber-Reinforced Concrete Beam-Column Joints Under Static and Cyclic Loading

The structural behaviour of beam-column connections with varying concrete layers was experimentally evaluated to enhance performance through hybrid fiber-reinforced concrete. A custom hybrid mix incorporating 0.3% glass fiber and 0.7% polypropylene fiber was developed, creating a reinforced layer with high-strength concrete in the beam section. Four beam-column joints were cast, featuring a dual-layer concrete design—hybrid fiber-reinforced concrete and high-strength concrete—and subjected to static loading tests. Comparative analysis with control specimens, devoid of fiber reinforcement, demonstrated a 22.9% improvement in ultimate load-carrying capacity. Crack patterns aligned with the "strong column-weak beam" principle, ensuring optimal failure mechanisms. Probability analysis confirmed the consistency and reliability of the hybrid fiber-reinforced layer in improving structural performance. The results highlighted significant gains in ductility, structural strength, and load-carrying capacity, offering a robust solution to durability and performance challenges in reinforced concrete beam-column connections. This investigation contributes to developing advanced materials for resilient structures, underscoring the benefits of combining hybrid fibers with high-strength concrete.