Axial behavior of carbon fabric‐reinforced cementitious matrix confined concrete‐filled geotextile tube stub columns

Abstract Recently, carbon fabric‐reinforced cementitious matrix (CFRCM) has become an attractive composite material for rehabilitation and strengthening concrete structures. However, considering its curing time, the construction efficiency of engineering is difficult to control in actual practice. Therefore, a novel composite structure named CFRCM confined concrete‐filled geotextile tube was developed and tested under axial compression, and its feasibility and effectiveness were also analyzed. Experimental results showed that the specimens with addition of carbon fabric failed in a ductile manner, characterized by shear cracks combined with fabric fracture. Compared to plain concrete, the axial behaviors of confined specimens were substantially improved. The peak strength increased by 8–24%, and the toughness increased by 88–259%, depending on the number of fabric layers (1–3). These enhancements were also influenced by concrete substrate strength and specimen cross‐sectional diameter. In addition, comparisons with concrete using conventional externally bonding techniques indicated that the proposed structure offers a promising alternative for achieving both performance and construction efficiency, although its post‐peak ductility was somewhat limited by the current forming quality of the confinement layer. Finally, a simple design‐oriented strength model was developed through regression analysis. Statistical comparison with several existing models demonstrated its competitive accuracy, showing good agreement not only with the test results in this study but also with a wider database of CFRCM‐confined concrete. It is anticipated that these results will pave the way for wider implementations for CFRCM confined concrete structures.