碳纤维加固钢筋混凝土受弯构件正截面疲劳理论与低温疲劳性能试验

Experiment on fatigue theory and low-temperature property of right section on CFPR-concrete bending structures

为了探索低温条件下碳纤维加固钢筋混凝土构件的疲劳性能,寻找疲劳破坏规律,展开了受弯构件正截面疲劳理论的推导研究。利用两根试验梁在-30^-20℃下进行疲劳加载试验,得出加固梁挠度、刚度、裂缝及疲劳强度的变化规律,对比研究了其在低温与室温下的疲劳性能。试验结果表明:低温疲劳荷载下,碳纤维布通过限制裂缝发展提高了混凝土梁的抗疲劳变形能力;加固梁的挠度明显小于室温疲劳荷载下的挠度,裂缝分布规律较好,裂缝宽度较小;碳纤维加固梁正截面疲劳承载力符合要求,具有一定的安全储备;现有的碳纤维加固梁跨中疲劳变形计算公式并不适用于低温情况。

To investigate the low-temperature property of CFPR-concrete structure in low temperature and dis-cover the fatigue changing rules,this study deduces the fatigue theory on the right section of bending structures. Experiments are conducted on two tested beams within the temperature range from -30 ℃ to -20 ℃.The changing rules of deflection,stiffness,fracture and fatigue strength were achieved.Then comparisons are car-ried out on fatigue property between low temperature and room temperature.The results show that CFPR sheet can improve fatigue deformation of concrete beams by constraining cracks.The deflection of reinforced concrete is remarkably smaller than that in room temperature fatigue loading.The cracks distribution is fine and the cracks width is tiny.The bearing capacity on the right section of CFPR-concrete structure meets the require-ment,and with safety storage.Current calculating formula on fatigue changing of mid-span of CFPR-concrete beam is not suitable for low-temperature conditions.