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根据混凝土I型裂缝扩展准则,将起裂断裂韧度作为材料参数,提出了一种新的计算混凝土结构裂缝扩展过程KR阻力曲线模型。该模型认为,裂缝扩展阻力由混凝土材料固有的抗裂能力和粘聚力提供的阻力组成并等于裂缝扩展的驱动力;应用该模型并借助有限元法计算了混凝土三点弯曲梁、楔入劈拉试件的裂缝扩展量、断裂过程区(FPZ)长度,在此基础上计算了混凝土试件的KR阻力曲线、研究了其尺寸效应,并与采用其他方法所计算的KR阻力曲线结果进行了比较。根据该文的研究结果,只要给出混凝土的弹性模量、抗拉强度和起裂断裂韧度,即可根据有限元法计算混凝土裂缝扩展过程的KR阻力曲线而无需测定混凝土试件的荷载-裂缝口张开位移等曲线。
According to the propagation criterion of concrete type I crack, fracture initiation toughness is taken as the material parameter, and a new model for calculating the resistance curve of the crack during the crack propagation process is proposed. The model considers that the crack propagation resistance is composed of the inherent cracking resistance of concrete materials and the resistance provided by cohesion and is equal to the driving force of crack propagation. The model is used to calculate the three-point bending beam of concrete by wedge-splitting The crack extension and the length of the fracture zone (FPZ) were obtained. Based on this, the KR resistance curve of the concrete specimen was calculated and its size effect was studied. The results were compared with the results of the KR resistance curve calculated by other methods Compare According to the research results in this article, given the elastic modulus, tensile strength and fracture toughness of concrete, the KR resistance curve of concrete crack propagation can be calculated according to the finite element method without the need of measuring the load of concrete specimen - Crack mouth open displacement and other curves.