混凝土软化本构关系对双K断裂参数的影响

混凝土裂缝扩展的双K断裂准则,用于描述混凝土结构裂缝的起裂、稳定扩展和失稳断裂。其相应的双K断裂参数K_ICⁱⁿⁱ、K_IC^un可通过简便的实验和基于虚拟裂缝扩展粘聚力的解析方法确定。已取得的研究结果表明,起裂韧度K_ICⁱⁿⁱ的解析解与所确定的混凝土软化本构关系有关。对于简单实用的双线性软化本构曲线而言,参数σ_s、w_s、w₀的取值直接影响软化本构关系的确定。根据本课题组新近所做楔入劈拉实验,经分析对比得到了与实测结果相符合、为确定双K断裂参数所使用的双线性软化本构曲线的相应参数。

THE INFLUENCE OF SOFTENING TRACTION-SEPERATION LAW OF CONCRETE UPON THE DOUBLE-K FRACTURE PARAMETERS

The double-K fracture criterion describes initiation, stable propagation and unstable propagation of cracks in concrete structures. The corresponding double-K fracture parameters (iniIcKandunIcK) introduced in the criterion can be determined using a simple experimental method combining with an analytical evaluation based on the cohesive force on the fictitious crack zone. The results show that the initial fracture toughness iniIcK depends on the softening traction-separation law used in the calculation. With regard to the convenient bilinear softening traction-separation law, the parameters ss、sw、0w will influence on the softening traction-separation law. Comparing with the results of wedge splitting tests which were conducted recently, the parameters in the softening traction-separation law can be determined to evaluate the double-K fracture parameters.