混凝土双K断裂参数计算的半解析有限元法

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(起裂断裂韧度$K_{\rm IC}^{\rm ini} $和失 稳断裂韧度$K_{\rm IC}^{\rm un}$)一般通过简便的试验和基于虚拟裂缝扩展粘 聚力的解析方法确定. 利用平面扇形域哈 密顿体系的方程，通过分离变量法及共轭辛本征函数向量展开法，以解析的方法推导出基于混 凝土虚拟裂缝扩展线性粘聚力模型的平面裂缝解析元列式. 将该解析元与有限元相结合，构成 半解析的有限元法，可求解任意结构几何形状的混凝土平面裂缝双$K$断裂参数的计算问题. 数值计算结果表明半解析有限元法对该类问题的求解是十分有效的.

Semi-analytical element method for double-K fracture parameters computations in concrete

The double-K tracture criterion describes initiation, stable propagation and unstable propagation of cracks in concrete structures. The corresponding double-K fracture parameters (initial cracking roughness K_(IC)~(ini) and unstable fracture toughness K_(IC)~(ini)) introduced in the criterion are determined using a simple experiment method combing with an analytical evaluation based on the cohesive force on the fictitious crack zone. Based on the Hamiltonian governing equations of plane elasticity for sectorial domain, the variable separation and eigenfunction expansion techniques are employed to develop a novel analytical finite element for the fictitious crack propagation linear force model in fracture mechanics of concrete in this paper. The new analytical element can be implemented into FEM program systems to solve computational problems of double-K fracture parameters for concrete cracked plane structures with arbitrary shapes. Numerical results indicate that the method is efficient and accurate.