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双K断裂准则能够定量描述混凝土结构裂缝的起裂、稳定扩展和失稳断裂。通过简便的试验和基于裂缝扩展粘聚力的解析方法 ,可计算双K断裂参数KiniIc和KunIc。反映粘聚力变化规律的软化本构曲线形状影响起裂韧度KiniIc的确定。对于简单实用的双线性软化本构曲线而言 ,取ws=CTODc,并引入一个直接影响混凝土软化本构曲线形状的参量λ ,结合本课题组新近所做的三点弯曲切口梁试验 ,调整参数λ ,得到了与实测结果相符的双线性软化本构曲线形状 ,用于确定双K断裂参数。
The double-K fracture criterion can quantitatively describe the initiation, steady expansion and instability faults of concrete structures. KiniIc and KunIc can be calculated by simple experiments and analytical methods based on crack propagation and cohesion. The shape of softening constitutive curve that reflects the variation of cohesion determines the determination of KiniIc. For a simple and practical bilinear softening constitutive curve, we take ws = CTODc and introduce a parameter λ that directly affects the softening constitutive curve shape of the concrete. Combined with the newly conducted three-point bending notched beam test of our group, Parameter λ, the shape of bilinear softening constitutive curve which is consistent with the measured result is obtained, which is used to determine the double K fracture parameter.