Seismic performance enhancement of hybrid fiber Reinforced Concrete beam–column joints using TRC strengthening and headed bar anchorage

Beam–column joints often experience severe congestion due to the large amount of transverse reinforcement and extended development lengths required to achieve ductile seismic behavior. This congestion leads to construction difficulties and compromises stress transfer in the joint core. This study aims to identify an efficient strengthening strategy that improves seismic performance while substantially reducing reinforcement demand. Hybrid fiber‐reinforced self‐compacting concrete (HFRSCC) was used to lower stirrup ratios, and headed bars were introduced to eliminate conventional development length and enhance anchorage. Pullout tests were conducted to optimize the anchorage system, and a helically ribbed headed bar configuration was identified as the most effective option. To further improve confinement with reduced internal rebar, two strengthening options—textile‐reinforced concrete (TRC) jacketing and an X‐bar configuration—were examined. Six exterior beam–column joints of 100 × 150 × 1000 mm were tested under cyclic loading to evaluate hysteresis response, stiffness degradation, crack behavior, energy dissipation, and damage progression. The results demonstrated that HFRSCC delayed crack initiation and improved ductility, while headed bars effectively controlled anchorage‐related failures without adding congestion. TRC strengthening of beam column joints with headed bars achieved the most favorable performance, attaining 133% higher peak cyclic load than the conventional joint, 41% higher than the HFRSCC joint, and 63% higher than the X‐bar joint, along with fuller hysteresis loops and superior energy dissipation. Although the X‐bar configuration enhanced performance, TRC exhibited higher ductility and relocation of plastic hinge. A Support Vector Regression model developed using 146 datasets predicted joint shear with a 96% correlation to experimental results, demonstrating high accuracy and confirming its suitability for design applications. Overall, the combination of HFRSCC, headed bars, and TRC provides a practical, congestion‐free, and highly effective solution for seismic strengthening of beam–column joints with reduced reinforcement and enhanced ductility.