锈蚀钢筋混凝土梁的疲劳性能

Fatigue Behavior of Corroded Reinforced Concrete Beams

为合理评估既有锈损混凝土桥梁的剩余疲劳寿命,对8根模拟锈蚀钢筋混凝土梁进行了高周疲劳试验,研究和探讨了锈蚀钢筋混凝土梁的疲劳性能。结果表明:交变荷载作用下试件的斜裂纹出现并迅速发展成主裂缝;模拟锈蚀钢筋混凝土梁多在端部发生剪切疲劳破坏;试件的挠度发展、裂缝分布与破坏形态密切相关;随循环次数增加,锈蚀主筋的最大、最小应力不断增长,应力幅值基本不变;混凝土的最大、最小压应变快速增长,应变幅值平稳增长;试件的疲劳寿命具有较大的离散性;同等条件下,模拟锈蚀钢筋混凝土梁的疲劳寿命往往比锈蚀钢筋的轴向拉伸疲劳寿命长。

In order to reasonably determine the remain fatigue life of existing corroded RC bridges,high-cycle fatigue tests were performed on eight corroded reinforced concrete( RC) beams,and the fatigue behavior of RC beams with corroded main reinforcing steel bars were investigated. The test results indicated that the diagonal cracks of specimens emerged and developed quickly under the alternate loads,finally became the main cracks. Most simulate corrosion RC beams appeared shear fatigue failure near the end. The deflection development and crack distribution of specimens were closely related with failure models. With the increase of cycle numbers,the maximum and minimal stresses of corrosion main reinforcement increased gradually,and the stress amplitudes changed little. The maximum and minimal compressing strain of concrete developed quickly,and the strain amplitudes increased stably. The fatigue life of specimens had more discreteness,and the fatigue life of the corroded RC beams was longer than that of natural corrosion reinforcing steel bars subjected to axial tensile fatigue loads under the similar corrosion and stress conditions.