循环荷载下含裂缝缺陷的混凝土断裂特性试验研究

Experimental Study on Compressive Properties of Defective Concrete Under Cyclic Loading

为研究含裂缝缺陷的混凝土在循环荷载作用下的断裂性能,利用MTS试验机对带有预制裂缝的混凝土三点弯曲梁试件进行了循环加载试验,获得了荷载-裂缝张口位移试验全曲线,据此得到了试验曲线的包络线和共同点轨迹线,并计算了试件的断裂能和滞回环的耗散能。通过对循环加载试验声发射信号的采集,分析了混凝土试件在该荷载历史下的声发射特性。结果表明:循环加载曲线的包络线与单调加载曲线相吻合,且共同点轨迹线与包络线的形状相似;两种循环加载试验得到耗散能与循环次数的曲线趋势相同,形状相似;循环加载试验中的声发射参数可以表征混凝土试件循环加载全过程的受力状态,并呈现出明显的Felicity效应。

In order to analyze the fracture characteristics of concrete with under cyclic loading,the cyclic loading tests were carried out on concrete three-point bending beam specimens with prefabricated chack by the defects MTS experimental machine,and the full curves of load-crack opening displacement were obtained for the whole testing process,from which the envelope curves and the common point curves of the testing curves were obtained,and the fracture energy of the specimens were calculated as well as the dissipated energy of hysteresis loops.The acoustic emission characteristics of concrete specimens under the load history were analyzed by collecting acoustic emission signals of cyclic loading tests.It was found that the envelope curves of the cyclic loading were consistent with the monotonic loading curves,and the shapes of the common-point trace curves were similar to the envelope curves.The two cyclic loading tests showed that the dissipated energy and the number of cycles had the same trend and similar shape.The acoustic emission parameters in the cyclic loading tests could characterize the stress state of concrete specimens during cyclic loading and showed a significant Felicity effect.