Fatigue bond behaviour between basalt fibre-reinforced polymer bars and seawater sea-sand concrete

Abstract

Basalt fibre-reinforced polymer (BFRP) bar-reinforced seawater sea-sand concrete (SSSC) structures have long-term development significance. However, there have been few systematic studies on the fatigue bond behaviour between BFRP bars and SSSC. Therefore, to fully understand the fatigue bond mechanism of BFRP bar-reinforced SSSC structures, the fatigue bond performance between BFRP bars and SSSC was thoroughly studied. Fatigue pull-out tests were conducted to study the influence of the concrete strength, bar diameters, surface shapes of BFRP bars, and stress levels on the fatigue bond behaviour. It was found that the total slip could be regarded as an inherent property of the bond between BFRP bars and SSSC, which had nothing to do with the loading process. Furthermore, the bond fatigue failure mode had great influence on the fatigue bond indexes, including the fatigue bond stiffness, slip at maximum fatigue bond stress, and residual fatigue slip. A fatigue bond model was proposed to reflect the fatigue bond behaviour. Meanwhile, a design method was proposed for predicting the fatigue life based on the slip at maximum fatigue bond stress. Finally, according to different surface shapes of BFRP bars, the fatigue bond mechanism between BFRP bars and SSSC was classified and discussed.