混凝土随机骨料结构在非线性有限元分析中的应用

Application of concrete random aggregate structure in nonlinear finite element analysis

在细观层次上,混凝土被认为是由粗骨料、砂浆以及它们之间的黏结带组成的三相非均质复合材料,这种复合材料的性质可通过混凝土细观随机骨料结构来模拟。提出一种适合于细观研究的非线性有限单元法,采用结合抗拉强度和开裂韧性的综合破坏准则,允许裂缝扩展时缝尖单元进行应力重分布,并用控制位移增量迭代法揭示混凝土峰值后的软化行为。随后用这一方法仿真模拟混凝土在单轴受拉和单轴受压时的整个加载过程,在细观层次研究的基础上揭示了混凝土的宏观性能。

Concrete is a composite material with a three-phase of inhomogenities in mesoscopic level.It is consisting of coarse aggregate、mortar matrix and interfacial zones between the coarse aggregate and the mortar matrix.Using random aggregate structure that resembles the mesoscopic structure of concrete can simulate the behavior of this material.A nonlinear finite element method suitable for mesoscopic study of concrete is developed.A failure criterion combining tensile strength and fracture toughness is adopted.Stress relief as cracks propagate is also allowed.An incremental displacement controlled iterative scheme that can deal with post-peak behavior is employed.The method is applied to simulate the process of real concrete trial under axial strain and axial stress.It obtains some behaviors of macroscopic concrete by studying at mesoscopic level.