Dynamic performance of seawater sea sand reinforced concrete composite beams confined with C-FRCM under lateral impact loads

The dynamic performance of seawater sea sand reinforced concrete (SSRC) composite beams confined with carbon-fabric reinforced cementitious matrix (C-FRCM) under lateral impact loads was experimentally investigated using the drop hammer test machine. In this study, a new type of composite beam was developed, by integrating C-FRCM with SSRC beams, which can be applied to ICCP-SS systems. A new casting method tailored for the SSRC composite beams confined with C-FRCM was proposed to favor the bonding between the C-FRCM and the SSRC beam, ensuring superior interfacial performance compared to traditional externally bonded FRP systems. Six SSRC composite beams were tested under static and lateral impact loads at varying velocities. Results showed that SSRC composite beams confined with C-FRCM exhibited improved resistance to impact loads, with an 8.4 % increase in impact load resistance and a 12.3 % increase in deflection capacity compared to conventional SSRC beams. The enhanced performance is attributed to the confinement and additional tensile resistance provided by the C-FRCM. The study also introduced a simplified calculation method to predict the maximum deflection under impact loads based on initial kinetic energy and static test results, providing a practical tool for engineering design. Additionally, a damage assessment method based on residual deflection was proposed to evaluate the impact resistance of the SSRC composite beams. The findings demonstrate that C-FRCM confinement significantly improves the dynamic performance of SSRC beams, making them suitable for applications in coastal and marine environments.