Bending behavior of concrete-filled FRP wound tubular arches with internal FRP bars

Conventional reinforced concrete arches are susceptible to corrosion in underground environments, leading to reduced durability. This study proposes concrete-filled FRP (Fiber-reinforced polymer) wound tubular arches with internal FRP bars to achieve excellent corrosion resistance. Eighteen concrete-filled FRP tubular arches were tested under mid-span concentrated loading, and the effects of FRP tube wall thickness and FRP reinforcement configuration were investigated. The experimental results demonstrate that increasing the wall thickness of the FRP tube significantly enhances the ultimate load-bearing capacity, with a maximum increase of 104.7% observed under mid-span loading. The incorporation of FRP reinforcement also resulted in 236.3%~279% increase of ultimate capacity and 111.11%-119.67% increase of displacement ductility ratio. A simplified theoretical model for predicting the ultimate load of concrete-filled FRP tubular arches with internal FRP bars was proposed, achieving a relative error within 10%. The proposed concrete-filled FRP tubular arch demonstrates considerable potential for application in underground engineering.