冻融作用下钢-PVA混杂纤维增强混凝土与钢筋黏结性能试验研究OA

In order to investigate the bond performance between steel-polyvinyl alcohol hybrid fiber reinforced concrete(S-PVA HFRC)and steel bars under freeze-thaw cycles,75 S-PVA HFRC specimens were designed and fabricated based on orthogonal test factors,namely steel fiber volume fraction,PVA fiber volume fraction,and mineral powder replacement rate.These specimens were subjected to freeze-thaw cycles with different numbers of cycles,followed by central pull-out tests under monotonic loading.The failure modes,bond strength,interfacial bond stiffness and toughness of S-PVA HFRC specimens under different test parameters were studied,and the influence of each parameter on the bond-slip mechanical behavior of S-PVA HFRC under freeze-thaw conditions was analyzed.The results show that all S-PVA HFRC specimens exhibit steel bar pull-out failure;the bond strength of S-PVA HFRC specimens decreases with the increase in the number of freeze-thaw cycles.After an identical number of freeze-thaw cycles,the bond strength and peak slip of S-PVA HFRC specimens are higher than those of fiber-free plain concrete specimens.After 50 freeze-thaw cycles,the bond strength of S-PVA HFRC specimens exhibit the most significant enhancement.Compared with fiber-free plain concrete specimens,the S-PVA HFRC specimens exhibit the greatest increase of 53.75%when the volume fraction of steel fiber is 1.3%,the volume fraction of PVA fiber is 0.2%,and the replacement rate of mineral powder is 15%(mass fraction).The incorporation of hybrid fibers effectively mitigates the adverse effect of freeze-thaw damage on the interfacial bond stiffness and significantly improves the energy dissipation capacity of the specimens.A bond-slip model for the interface between S-PVA HFRC and steel bars under freeze-thaw conditions is proposed,which shows good agreement with the experimental results.