Pullout behaviors of basalt fiber-reinforced polymer bars with mechanical anchorages for concrete structures exposed to seawater

Abstract

This study presents an investigation of the pullout behaviors of basalt fiber-reinforced polymer (BFRP) bars with mechanical anchorages in concrete exposed to seawater. A total of forty-eight pullout specimens were prepared. Three types of mechanical anchorages that can be flexibly assembled on FRP bars, that is, additional straight bar, additional hook, and composite head, were adopted. The experimental variables comprised the anchorage type, conditioning temperature, and conditioning duration. The maximum pullout load (Pmax) and corresponding slip (smax), and the plateau length at the peak (lp) and slope of the descending branch (kd) of the load-slip curves, were evaluated and discussed. The results show that mechanical anchorages contribute to significant increases in the lp and decreases in the kd. Furthermore, the composite head achieves 32 % and 10 % increases in Pmax and lp respectively, and 20 % and 36 % decreases in smax and kd respectively, compared with the other two types of anchorages. After conditioning in seawater, the specimens with composite heads exhibit no significant degradation in their pullout behaviors, which indicates the effectiveness of the composite head in the protection against corrosive media. These results demonstrate the application prospects of a composite-head mechanical anchorage for FRP reinforcement in concrete structures constructed in the marine environment.