Effect of Strain Rate on the Bond Performance of Carbon Fiber–Reinforced Polymer Tendons in Ultrahigh-Performance Concrete

Abstract

This paper aims to investigate the contribution of chemical adhesion and friction to the bond stress of a smooth carbon fiber–reinforced polymer (CFRP) tendon in ultrahigh-performance concrete (UHPC) under different strain rates by conducting static tensile and drop-weight impact tests. The influences of strain rate and embedded length on the bond performance were revealed, and the components of the bond stress for the smooth CFRP tendon in UHPC were analyzed. The results showed that an increase in the strain rate improved chemical adhesion but exhibited an adverse effect on friction. In comparison with specimens subjected to static tension, the chemical adhesion of the specimens under strain rates from 3.10 to 4.87 s−1 increased on average by 48%–78%, while the friction decreased on average by 34%–45%; however, the effect of embedment length was marginal. Based on a comparison of the bond strengths of smooth and ribbed CFRP tendons, the decrease in the interlocking interaction was considered to be responsible for the low dynamic bond strength. Finally, formulas were developed to predict the dynamic bond strength and critical anchorage length of smooth CFRP tendons in UHPC under impact events.