|
Title |
Evaluation of the Local Bond Behavior of Triple Hybrid Nano-Reinforced Concrete under Cyclic Pullout Loading
|
|
Authors |
박성관(Seong-Gwan Park) ; 이문석(Moon-Seok Lee) ; 최창식(Chang-Sik Choi) ; 배백일(Baek-Il Bae) |
|
DOI |
https://doi.org/10.11112/jksmi.2026.30.4.77 |
|
Keywords |
삼중 하이브리드 나노보강 콘크리트; 반복하중; 부착거동; 부착응력; 누적 소산에너지 Triple hybrid nano-reinforced concrete; Cyclic loading; Bond behavior; bond stress; Cumulative dissipated energy |
|
Abstract |
This study evaluated the local bond behavior of triple hybrid nano-reinforced concrete incorporating carbon nanotubes (CNTs), nano-silica (NS), and graphene oxide (GO) under cyclic pullout loading. The main variables were the nanomaterial incorporation ratio, namely OPC, 0.5N, and 1.0N, and the cover-to-bar diameter ratio. Material test results showed that 1.0N improved both compressive and splitting tensile strengths, whereas 0.5N mainly increased the splitting tensile strength with little improvement in compressive strength. In the cyclic pullout tests, all specimens exhibited pull-out failure, and the measured rebar strains remained below the yield strain, indicating that the test results were governed by bond deterioration rather than rebar yielding. The forward peak bond stress did not increase consistently with nanomaterial incorporation. However, the 1.0N specimens showed higher initial stiffness, delayed peak bond stress development, and improved post-peak residual bond performance. The initial stiffness of 1.0N increased by 66.3% and 23.4% for the 100 mm and 125 mm specimens, respectively, compared with OPC. At a slip of 3.0 mm, the residual bond stress ratios of 1.0N were 0.76 and 0.51, which were significantly higher than those of OPC. In addition, 1.0N maintained reverse-to-forward peak bond stress ratios of 0.92?0.96 and increased cumulative dissipated energy by up to 251.7% compared with OPC. These results indicate that the primary effect of triple hybrid nano-reinforcement is not a simple increase in forward peak bond stress, but rather the enhancement of initial bond stiffness, resistance to post-peak softening, residual bond performance, and energy dissipation capacity under cyclic loading.
|