Acoustic emission fractal characteristics analysis of steel fiber reinforced concrete during uniaxial tensile damage

Abstract

In order to study the influence of steel fiber on the damage characteristics of concrete under uniaxial tension, based on the improved G-P algorithm, the acoustic emission event rate correlation dimension (hereinafter referred to as correlation dimension) curves of steel fiber reinforced concrete under uniaxial tension failure before and after peak stress were obtained, and the evolution characteristics of the correlation dimension of concrete with different steel fiber contents analyzed. According to the correlation dimension, the R value, the F value and the variance (σ2) were proposed to measure the effect of steel fiber on the micro-failure characteristics of concrete. The results show that before peak stress, the correlation dimension first increases and then decreases with an increase in the stress level; the mean correlation dimension increases with an increase in steel fiber; the addition of steel fiber reduces the R value by 36.13 % to 65.04 % compared with plain concrete, but has little effect on the F value. After peak stress, with a decrease in the stress level, the correlation dimension decreases with some fluctuation; and the variance of correlation dimension decreases with the increase of steel fiber; whereas the order degree of the system microstructure, measured by the correlation dimension, increases with an increase in steel fiber. These results can be used for structural health monitoring and the non-destructive testing of steel fiber reinforced concrete, which have an important value for enriching the early warning of fracture failure in steel fiber reinforced concrete based on acoustic emission technology.

Fractal characteristics and damage evaluation of corroded beams under four-point bending tests based on acoustic emission techniques

“…The results indicated that more severe damage would appear when the correlation dimension is stable after damage. Wang et al [37] investigates the effect of steel fibers on the damage characteristics of concrete under uniaxial tension based on the fractal method. The results showed that the correlation dimension increased and then decreased with increasing stress level before the peak stress; the average correlation dimension increased with the increase of steel fibers.…”