Analysis of Dynamic Tensile Process of Fiber Reinforced Concrete by Acoustic Emission Technique

Abstract

The fiber reinforced concrete has good dynamic mechanical properties. But corresponding research lacks the dynamic damage characteristics of the polypropylene fiber (fiber of low elastic modulus) and steel fiber (fiber of high elastic modulus) reinforced concrete under medium strain rate (10^-6 s^-1-10^-4 s^-1). In order to study the effect of strain rate on the damage characteristics of fiber reinforced concrete during the full curve damage process, the real time dynamic acoustic emission (AE) technique was applied to monitor the damage process of fiber reinforced concrete at three strain rates. The AE wavelet energy spectrum in ca8 frequency band and average AE peak frequency at three strain rates were analyzed. With the accumulation of damage, the AE wavelet energy spectrum in ca8 frequency band increased first and then decreased, and the average AE peak frequency increased gradually. With the increase of strain rate, the AE wavelet energy spectrum in ca8 frequency band and average AE peak frequency decreased gradually. The polypropylene fiber content has more obvious effect on the Dynamic increase factor (DIF) of the peak stress than the steel fiber content. The theoretical basis was provided for the monitoring of dynamic damage of fiber reinforced concrete based on the AE technique.

Keywords

acoustic emission / steel fiber / polypropylene fiber / strain rate / acoustic emission wavelet energy spectrum / peak frequency