粉煤灰掺量对应变硬化水泥基复合材料力学性能及损伤特征的影响

Effect of Fly Ash Content on Mechanical Properties and Damage Characteristics of Strain-Hardening Cementitious Composites

摘要:

通过单轴拉伸、三点弯曲和抗压强度试验，研究粉煤灰掺量对应变硬化水泥基复合材料（SHCC）力学性能和损伤特征的影响，并利用数字图像相关技术对整个拉伸加载过程进行分析，提出利用开裂面积和分形维数量化SHCC试件的损伤程度，得到SHCC在加载过程中的应变演化和损伤特征.结果表明：随着粉煤灰掺量的增加，SHCC的拉伸强度、抗压强度及抗弯强度均逐渐降低，耗能能力逐渐提高，变形性能得到改善，但损伤程度增加；通过数字图像相关技术获得的应变云图可以直观观测SHCC的应变演化；开裂面积比和分形维数能够有效表征SHCC的损伤程度及开裂复杂性，可作为描述其损伤的度量指标.

Abstract:

The effect of fly ash content on the mechanical properties and damage characteristics of strain-hardening cementitious composites （SHCC） was studied by uniaxial tensile， three-point bending and compressive strength tests. The whole tensile loading process was analyzed by using digital image correlation techniques. The cracking area and fractal dimension were proposed to quantify the damage degree of SHCC specimens， and the strain evolution and damage characteristics of SHCC during the loading process were obtained. The results show that with the increase of fly ash content， the tensile strength， compressive strength and flexural strength of strain hardening cementitious composites （SHCC） gradually decrease， the energy consumption capacity gradually increases. Its deformation performance is improved， though the damage degree increases. The strain evolution of SHCC can be visualized by the strain cloud map obtained by the digital image correlation technique. The cracking area ratio and fractal dimension can effectively characterize the damage degree and cracking complexity of SHCC， which can be used as measurement indexes to describe its damage.