重复荷载下高强钢筋与混凝土黏结性能的试验研究

随着预应力钢筋强度的提高及钢筋外形的变化,加之抗震设计必须考虑的黏结退化,钢筋与混凝土之间的黏结锚固问题愈显突出。通过光圆钢棒、异形钢棒和螺旋肋钢丝拉拔试件在重复荷载作用下的拔出试验,比较了3种不同外形高强预应力钢筋的黏结特性,研究了螺旋状预应力钢筋与混凝土界面间的黏结锚固机理,并讨论了影响黏结锚固性能的主要因素。根据试验结果,给出3种高强预应力钢筋在等幅重复荷载作用下的特征荷载值与应力水平上限的关系式。结果表明光圆钢棒在重复荷载作用下与混凝土的黏结性能较差;而异形钢棒和螺旋肋钢丝具有较好的黏结性能,且螺旋肋钢丝的黏结性能优于异形钢棒。研究成果为承受重复荷载的此种高强预应力钢筋混凝土结构的设计提供了依据。

An experimental study of the bonding behavior between high-strength steel bar and concrete under repeated loadings

With the improvement in prestressing tendon strength,variations in deformation patterns of rebars,and the necessity of bond deterioration in earthquake-resistant designs,the bond anchorage between reinforcement and concrete has become an increasingly acute issue.The pullout specimens of round steel bars,deformed steel bars and helical rib steel wires were tested under repeated loadings.Bond behaviors of the interfaces between 3 surface patterns of prestressing tendons and concrete were compared,the bond mechanisms between the helical prestressing tendons and concrete were explained,and the main influencing factors on bond anchorage performance were discussed.Based on the experimental results,the relationships between characteristic loads and maximum stress levels were obtained under repeated constant-amplitude loadings.The results indicate that the bond between round steel bars and concrete under repeated loadings is weak,whereas the bond for deformed steel bars is better and that for helical rib steel wires is the best.