Bond Behavior of Stainless Steel Reinforcement and Seawater Sea-Sand Concrete under FRP-Steel Confinement

Abstract

The combination use of stainless steel (SS) bars and seawater sea-sand concrete (SSC) is attractive for coastal and marine infrastructures due to the excellent corrosion resistance of SS and the eco-friendly property of SSC. Against this background, a total of 88 central pullout specimens were tested to investigate the bond behavior of SS reinforcement and SSC under different confinement levels provided by stainless steel stirrups and fiber-reinforced polymer (FRP) sheets. Several variables were designed in the present test, including the concrete type and strength, the thickness of concrete cover, rebar type, embedment length, and confinement type and level. The failure modes, bond-slip relationships, and ultimate bond strength were analyzed systematically. Test results reveal that splitting failure can be effectively prevented under sufficient confinement. The ultimate bond strength of SS bars in SSC can improve by at least 13.19% compared to counterparts in normal concrete (NC), and the enhancement of bond strength ranges from 0.49% to 37.49% with varying embedment length ratio. The confinement effects of concrete cover, stirrup, and FRP are also interpreted quantitatively by using a developed coefficient. Finally, a new bond-slip model considering dual confinement of FRP sheets and steel stirrups for SSC is developed and the proposed model performs well by comparing the theoretical predictions with the test results from this study and other relevant literature.