Experimental study on fracture properties of dam concrete under post‐peak cyclic loading based on DIC and acoustic emission techniques

Abstract

In order to study the fracture properties of dam concrete under post-peak cyclic loading, wedge splitting tests with three loading rates were performed on notched cubic specimens. Meanwhile, the acoustic emission (AE) and digital image correlation (DIC) technologies were used to monitor crack propagation in the specimens. As the loading rate increases, the peak load increases, and stiffness degradation increases. The cumulative AE counts show a step increasing trend and exhibit a Kaiser effect, which decreases via the post-peak cyclic loading procedure and increases as the loading rate increases. The AE energy fluctuates markedly, and b value fluctuates frequently with an increasing loading rate. As the loading rate increases, the strain recovery rate decreases, and the permanent crack increases. The effective crack length gradually and steadily increases, and as the loading rate increases, the growth rate of the effective crack length increases.

Evaluation Method for the Bearing Capacity of Reinforced Concrete Beams Based on the Kaiser Effect

“…When the stress level is greater than 30% of the ultimate stress (lower limit) and less than 80% (upper limit), the Kaiser effect is obvious, the Felicity ratio is generally greater than 1, and the upper limit of stress depends on the failure mechanism of the material, while the lower limit of stress depends on the structural characteristics of the material itself [14]. Thus, the Kaiser effect acquired from concrete has been studied from the perspectives of the AE characteristics of the materials under different loads in most cases [15][16][17][18][19]. However, few studies have highlighted the Kaiser effect of concrete components and structures, particularly on the AE characteristics of the whole process of concrete beam failure [20][21][22][23][24].…”