反复荷载下腐蚀钢筋与混凝土的粘结特性

Bonding Behavior of Corroded Steel-reinforcement with Concrete under Cyclic Loading

试验研究了混凝土中腐蚀钢筋在反复荷载作用下的粘结-滑移特性。研究的参数包括:钢筋腐蚀率和钢筋的侧向约束。试验结果表明,钢筋腐蚀率较低时,腐蚀减弱了加载过程中的粘结强度损失。而腐蚀率较高时,腐蚀则显著增大了粘结强度损失,卸载时的粘结应力水平仅为加载时的3/4。无约束试件在达到最大粘结应力之后劈裂破坏,此时的滑移很小。与此形成对比,受约束试件最终表现为拔出破坏,此时的相对滑移较大但裂缝宽度较小,约为0.2mm。较之于有约束试件,无约束试件的粘结强度随腐蚀率变化的趋势更为显著。较高腐蚀率时,前5个加载循环会引起较大的粘结损失。

The relationship between bond stress and slip displacement of corroded reinforcement with concrete under evclie loading has been experimentally investigated. The parameters investigated include reinforcement corrosion rate and lateral restraint of speeiments. The results show that a lower level of corrosion help to reduce the bond loss during h,ading, while higher level corrosion significantly increase the bond loss. The valumes of bond stress in unloading was only as large as three-fourth of that in loading period. In nnrestraint specimens, at the slip displacement was very small, the splitting failure of concrete was observed when the maximum bond stress was reached. As a comparison, the pullout failure was generally ohserved in restraint specimens and the slip was much larger while crack width was small, about 0.2mm, The changes of bond strength in unrestraint specimens with increase of corrosion are more obvious than in retraint ones. A higher level corrosion caused larger bond decrease in the first five loading eycles.