Flexural behavior evaluation of concrete filled small-angle winded GFRP tube columns

In harsh environments such as ocean engineering, reinforced concrete structures suffer from severe corrosion, and concrete-filled fiber-reinforced polymer tubes (CFFT) have been widely used as a substitute for them. In this paper, extremely small-angle GFRP tubes are manufactured using the winding process and the flexural behavior of ±55° and ±15° angle-ply GFRP tube columns is investigated. The effects of the winding angle on the flexural behavior of CFFT were studied by experiment. The experimental results showed that the failure modes of CFFT were dominated by fiber rupture, slip between concrete and GFRP tube, and concrete crushing. Reducing the winding angle and filling concrete can effectively improve the ultimate flexural load by 117.25%, and 182.01%, respectively. Furthermore, a numerical model was established to predict the flexural behavior of CFFT, the Concrete Damaged Plasticity model was used to simulate the behavior of the concrete, and the Hashin failure criterion was used for the GFRP tube. The predicted failure modes and load-displacement curves were in good agreement with the experimental results. Parametric analysis showed that increasing the GFRP tube thickness can improve the ultimate flexural load by 62.72% and increasing concrete strength changes the failure mode of CFFT from GFRP tube rupture to concrete damage.