基于碳纤维混凝土机敏性的Ⅱ型断裂试验研究

Experimental Research of Mode Ⅱ Fracture Based on Self-monitoring Behavior of Carbon Fiber Reinforced Concrete

针对Ⅱ型断裂韧度KⅡc较难确定的现状,利用碳纤维混凝土的机敏性对有限宽两端切口半边受力试件的断裂性能进行了考察.结果表明,碳纤维混凝土的导电性能随荷载和位移显著变化,并呈现洛伦兹曲线关系;碳纤维混凝土的机敏性可以被用来确定该型试件的KⅡc,其值要大于素混凝土的KⅡc;在峰值荷载前的电阻变化率曲线可以用来表征试件在试验过程中的弹性变形阶段、裂缝稳定开展阶段和裂缝失稳开展阶段.

Because it is difficult to determine fracture toughness of pure mode Ⅱ fracture, the self-monitoring behavior of carbon fiber reinforced concrete was used to investigate mode Ⅱ fracture of double edge notched specimen. The results show that resistance increases with increase of load and displacement, which shows relationship like Lorentz curve. Self-monitoring behavior of carbon fiber reinforced concrete can be used to ascertain K ncvalues of double edge notched specimen, which are found to be higher than that of normal strength concrete. The curves of fractional change in resistance before maximum load can illustrate three stages, that is, such as elastic deformation, stable fracture and unstable fracture .