混凝土梁腐蚀疲劳刚度衰减规律

Study on the law of fatigue stiffness decay of reinforced concrete beams subjected to corrosion fatigue

为研究腐蚀环境下钢筋混凝土梁的刚度衰减规律,对空气环境、淡水环境、盐水环境中的试验梁在循环荷载作用下的混凝土模量和试验梁的刚度进行了分析.根据钢筋混凝土梁在腐蚀疲劳下钢筋与混凝土的应变、残余应变、挠度等试验结果,得到了受弯构件正截面混凝土腐蚀疲劳模量降低率和构件腐蚀疲劳刚度的衰减规律.结果表明,虽然试验过程中混凝土并没有遭受明显腐蚀,但其疲劳模量却有所降低,降低的速率依试验环境的不同而不同.主要是钢筋腐蚀疲劳发展,截面协同工作的结果.试验梁的腐蚀疲劳刚度降低速率亦较快,在不同的腐蚀环境中疲劳刚度降低的速率也不同,以盐水环境中刚度衰减的最快.主要原因是构件中钢筋腐蚀疲劳裂纹的不断扩展导致构件刚度的降低.

In order to study the decaying law of stiffness of reinforced concrete beams in aggressive environment, the fatigue module of concrete and the stiffness of beams subjected to cyclic loading in the air, water and salt solution were analyzed. Based on the strain of reinforcement and concrete, residual strain and deflection tested in the experiment of reinforced concrete beams subjected to corrosion fatigue, the decreasing rate of corrosion fatigue module of concrete and the decaying law of fatigue stiffness of flexural members were obtained. The results show that the fatigue modules of concrete decrease whereas the concrete does not suffer from significant corrosion in the experiment. The decreasing rate of fatigue modules is different in various environments due to the development of the reinforcement corrosion fatigue and the coordinated working of the section between reinforcement and concrete. Also the measured decreasing rate of corrosion fatigue stiffness of the beam is different in various environments, which is the fastest in the salt solution. The main reason is the continuous developing of corrosion fatigue cracking of reinforcement leading to the decreasing of stiffness of the beams.