Concentrically loaded concrete columns reinforced with steel-FRP composite bars (SFCB) and carbon fibre-reinforced polymer mesh fabric (CFRP-MF) stirrups

Corrosion of rebar is a major cause of performance degradation in coastal structures, and thereby, significantly affects their durability and safety. To address this issue, a new corrosion-resistant reinforced composite structural concrete column were formed by using basalt fibre-reinforced composite bar (SFCB) as the longitudinal reinforcement and carbon fibre-reinforced polymer mesh (CFRP-MF) as an alternative to stirrup. Eight columns were subjected to an axial compression test to determine their capacity. The effects of different combinations of embedded reinforcement, concrete strength, and CFRP-MF stirrup ratio on the cracking performance, ductility, and axial load carrying capacity were investigated. A nonlinear finite element modelling was used to predict axial compressive response of concrete column reinforced with SFCB and CFRP-MF stirrups, and parametric analyses were conducted. The experimental results indicated that all tested columns reinforced with CFRP-MF stirrups were damaged in the central region of the specimens with extensive peeling of the protective layer. To ensure optimal structural safety, it is recommended that SFCB adopt the equal stiffness alternative method to replace longitudinal reinforcement. The substitution increases load-carrying capacity and ductility of the specimen by 5.4 % and 7.8 %, respectively. The study proposes an improved design model for predicting the N_u of columns reinforced with SFCB and CFRP-MF stirrups, which enhances prediction accuracy and precision when compared with existing codes. The findings contribute innovative insights and practical recommendations for advancing the utilization of seawater sea sand concrete and its application in coastal engineering projects.