Size effect of the post-peak cyclic behavior of plain concrete in uniaxial tension with acoustic emission technique

At present, studies about the size effect of concrete mainly focus on macroscopic mechanical behaviors like strength and fracture energy, while research on the size effect of the cyclic nonlinear properties of concrete is very rare. To further analyze the ambiguous concept of specimen size, three types of precut cylindrical concrete specimens with the same diameter but different heights, the same height but different crack depths, and the same aspect ratio but different volumes are used for the uniaxial post-peak cyclic tensile test. At the same time, the acoustic emission (AE) device is used to monitor and collect the AE signals in the loading process. According to the test results, no size effect exists in the accumulation of residual deformation, but the degradation of the unloading modulus is related to the specimen diameter. Meanwhile, the Kaiser effect is found in the analysis of AE signals. After the data analysis, a post-peak cyclic tensile model of concrete is proposed based on the size effect and damage evolution. The quantitative relationship among the model parameter, specimen aspect ratio, and damage is calculated. Finally, a good comparison is found between the predicted model and experimental result. © 2019 by ASTM International.