Mixed Mode Fracture of Concrete

这项拟议研究的目的是继续华盛顿大学先前关于钢筋混凝土构件斜拉破坏的混合型混凝土断裂方面的研究。具体地说，将使用裂纹线楔形加载的双悬臂梁试件来研究剪切传递机制，这种机制被认为可以阻止稳定的裂纹扩展，这些试件具有较短的起始裂纹和不同的随裂纹长度变化的加载历史。用云纹干涉法同时测量两个正交位移场，由此可确定裂纹张开位移和稳定扩展的对角拉伸裂纹的滑移。莫尔数据和加载数据将与有限元程序交互使用，以推导复合型加载下断裂过程区的裂纹闭合和剪力。通过实验和数值分析相结合的方法，推导出复合型稳定裂纹扩展准则。结果将与断口的断口和轮廓仪分析相关联，以评估不同成分(硬化水泥浆体、粗骨料和细骨料等)的相对微观力学贡献。混凝土的混合型断裂。

The objective of the proposed research is to continue prior University of Washington studies on mixed-mode concrete fracture aspects of diagonal tension failure in reinforced concrete members. Specifically, the shear transfer mechanism, which is thought to resist stable crack growth, will be studied using crack-line wedge- loaded, double cantilever beam specimens with short starter cracks and various loading histories which are crack-length dependent. Moire interferometry will be used to measure simultaneously two orthogonal displacement fields from which the crack opening displacement and the slip of stably growing diagonal tension cracks will be determined. Moire data together with the loading data will be used interactively with a finite element code to deduce the crack closure and shear forces in the fracture process zone under mixed mode loading. Mixed mode stable crack growth criterion will be deduced from this hybrid experimental-numerical analysis. The results will be correlated with fractography and profilometer analyses of the fractured surfaces in order to assess the relative micromechanic contributions of the various constituents (hardened cement paste, coarse aggregate and fine aggregate, etc.) to mixed mode concrete fracture.