基于分形理论和扩展有限元法的钢纤维混凝土损伤破坏机理

为研究钢纤维混凝土损伤破坏过程和裂纹发展演化机理,基于分形理论和扩展有限元法,建立钢纤维混凝土立方体抗拉试验细观有限元模型和切口梁三点弯曲试验有限元模型,以相关试验测试结果为基础,比较验证了所建有限元分析模型的可靠性。以裂纹分形维数表征钢纤维混凝土损伤演化过程,考察不同钢纤维体积掺量和长度、粗骨料形状等重要因素对钢纤维混凝土损伤演化过程的影响。结果表明,基于裂纹分形维数的损伤值可以较好地反映钢纤维混凝土的损伤演化过程及特征,钢纤维体积掺量、长度的增加和骨料形状的不规则化会延缓钢纤维混凝土立方体试件的损伤演化过程,钢纤维体积掺量、初始裂纹距跨中距离的增加和初始裂纹缝高比的减小可在较小程度上延缓钢纤维混凝土切口梁的损伤演化过程。

Damage and Failure Mechanism of Steel Fiber Reinforced Concrete Based on Fractal Theory and Extended Finite Element Method

In order to study the damage and failure process of steel fiber reinforced concrete and the mechanism of crack development and evolution, based on fractal theory and extended finite element method, the mesoscopic finite element model of steel fiber reinforced concrete cube tensile test and the finite element model of notched beam three-point bending test were established. The reliability of the established finite element analysis model was compared and verified based on the relevant test results. The damage evolution process of steel fiber reinforced concrete was characterized by the fractal dimension of crack, and the effects of different volume content and length of steel fiber, the shape of coarse aggregate and other important factors on the damage evolution process of steel fiber reinforced concrete were investigated. The results show that the damage value based on the fractal dimension of crack can better reflect the damage evolution process and characteristics of steel fiber reinforced concrete. The increase of steel fiber volume content and length and the irregularity of aggregate shape will delay the damage evolution process of steel fiber reinforced concrete cube specimens. The increase of steel fiber volume content and the distance between the initial crack and the midspan, and the reduction of the initial crack height ratio can delay the damage evolution process of steel fiber reinforced concrete notched beams to a small extent.