锈胀钢筋混凝土梁疲劳性能试验研究

Experimental study on fatigue behavior of reinforced concrete beams with corrosion-induced cracking

为研究锈胀对钢筋混凝土梁疲劳性能的影响,采用电化学快速锈蚀试验得到了不同锈胀程度的钢筋混凝土梁,讨论了初始锈胀裂缝的宽度及分布情况。开展了钢筋混凝土梁的静力及疲劳试验,研究了不同疲劳循环次数后梁的荷载-挠度关系、混凝土疲劳裂缝发展、疲劳寿命及失效模式。试验结果表明:相同静载水平下梁的跨中挠度随疲劳循环的增加而增大,经历相同疲劳循环后梁的刚度退化对锈胀程度敏感性大;锈胀钢筋混凝土梁混凝土裂缝数量减少、裂缝平均间距增大,锈胀程度较低梁的混凝土疲劳裂缝发展具有明显的"三阶段"特征;疲劳试验梁均发生了以纵向主筋疲劳断裂为主要标志的脆性失效形式;锈胀降低钢筋混凝土梁的疲劳寿命,锈胀引起混凝土剥离梁的疲劳寿命下降90%以上。

This paper aims to study the effect of corrosion-induced cracking on the fatigue behavior of reinforced concrete beams. An accelerated corrosion test is performed to obtain different cracking reinforced concrete beams. The initial crack width and crack distribution are discussed. Static loading tests and fatigue tests are conducted. The load-deflection relationship, fatigue crack propagation of concrete, fatigue life and failure mode after various fatigue cycles are analyzed. The experimental results show that the deflection in mid-span increases with the increase of fatigue cycles under the same load level. The stiffness of beam is sensitive to corrosion crack degree after the beams are subjected to a same fatigue cycle. For the beam with corrosion cracks, the number of concrete fatigue cracks decreases and the average crack spacing increases. A key feature of ＂three stage＂ is presented in concrete fatigue crack propagation for the beam with a lower crack degree. All the beams occur a brittle failure as fatigue fracture of reinforcing bars. Corrosion crack decreases the fatigue life of reinforced concrete beam. The decreased ratio of fatigue life for the beam with concrete spalling is about 90% of uncorroded beam.