Shear behavior of coral aggregate concrete beams reinforced with steel–FRP composite bars: An experimental investigation and predictive modeling using generalized additive models

Steel-Fiber Composite Bar (SFCB)-reinforced Coral Aggregate Concrete (CAC) structures have broad application prospects in coastal and marine engineering. To investigate the shear behavior of SFCB-CAC beams, this study conducted tests on two stirrup-free beams and six stirrup-reinforced beams, with key parameters including stirrup configuration( ρ v ), shear span-depth ratio ( a/d ), and reinforcement ratio( ρ f ). The results show that the shear failure modes of SFCB-CAC beams are similar to those of traditional reinforced concrete beams, and the fibers and steel core of SFCB have good bonding performance. The provision of stirrups can significantly improve the bearing capacity and ductility of beams, with the optimal ductility achieved when the a/d ratio is 2. As the a/d ratio increases from 1 to 3, the cracking load, yield load, and ultimate load decrease by 67.52%, 65.42%, and 68.02%, respectively. When the ρ f of SFCB increases from 1.14% to 1.49%, the shear bearing capacity increases by 9.2%, while ductility decreases by 21.69%. This study established a database containing 156 samples and trained a high-precision machine learning model for shear capacity prediction. Furthermore, the existing formula was modified using test analysis and SHAP interpretation results, with verification showing good agreement between the modified formula's predictions and test values. This study provide valuable references for SFCB-CAC structures as a replacement for traditional reinforced concrete structures in marine engineering.