Grout sleeve splicing of steel-fiber reinforced polymer composite bars: Tensile behavior and bond mechanism

In reinforced concrete structures exposed to harsh environments, steel corrosion poses a significant problem. Ductile and durable steel-fiber reinforced polymer composite bars (SFCBs), which can effectively address this issue, are a perfect alternative to conventional steel bars. However, the lack of suitable connection methods for SFCB has hindered their widespread adoption in civil engineering. To address this limitation, this paper proposes the use of grout-filled steel sleeves as a solution for connecting SFCB. The study designed 120 specimens of grout sleeve splices for SFCB to investigate their performance under unidirectional tensile forces. The experimental variables included the ratio of grout thickness to SFCB diameter, SFCB diameter, anchorage length, and grout strength. The results revealed various failure modes and found that specimens with a smaller ratio of grout thickness to SFCB diameter and greater grout strength demonstrated higher peak stress. The peak stress first increases and then slowly declines with an increase in anchorage length. Additionally, the peak stress decreased with increasing SFCB diameter, and the peak slip remained constant. Meanwhile, the bond mechanism between SFCB and grout was revealed. Finally, the study derived a theoretical bond-slip curve between SFCB and grout, as well as the development anchorage length.