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混凝土尺寸效应及其宏观力学非线性根源于其材料细观组成的非均质性。结合混凝土细观结构形式,将混凝土看作由骨料颗粒、砂浆基质及界面过渡区组成的复合材料。采用双线性弹性损伤模型来描述砂浆基质及界面过渡区的力学行为,假定骨料颗粒为弹性体而不发生破坏,进而推导并获得了单轴拉伸条件下不同骨料颗粒级配混凝土断裂裂缝扩展路径长度及其抗拉强度的理论解。最后,对比了建立的理论公式结果与细观尺度数值模拟结果,验证了构建的关于裂缝长度及抗拉强度理论解的准确性和合理性。
The size effect of concrete and its macroscopic mechanical nonlinearity are attributed to the heterogeneity of the mesostructure of the material. Combined with the concrete meso-structure, the concrete is considered as a composite material composed of aggregate particles, mortar matrix and interfacial transition zone. The bilinear elastic damage model is used to describe the mechanical behavior of the mortar matrix and the interface transition zone. Assuming that the aggregate particles are elastomers without damage, the fracture of the aggregate-graded concrete under uniaxial tension is deduced and obtained Theoretical solution to crack propagation path length and tensile strength. Finally, the results of theoretical formula and numerical simulation are compared, which verify the accuracy and rationality of theoretical solution for crack length and tensile strength.