Real-time localization of micro-damage in concrete beams using DIC technology and wavelet packet analysis

Abstract

As the service time of large civil engineering structures increases, structural health monitoring providing early warning information becomes increasingly important. In this study, three reinforced concrete beams were poured as specimens, and four-point bending experiments were conducted to investigate the localization of the micro-damage of the specimens. Three-dimensional digital image correlation (DIC) technique was employed to acquire and handle the images of changes in the surface of the specimens under various loads during the experiment. Then, Daubechies wavelet with 3 layers and order N of 10 was utilized to extract the energy spectrum of the principal strain nephogram obtained by DIC. The energy change rate (ECR) and energy change rate standard deviation (ECRSD) were defined and selected as micro-damage identification indicators. Then the ECR and ECRSD were calculated in full-filed and partial-field respectively with the energy spectrum acquired by Daubechies wavelet. Finally, a calculation process with detailed steps was proposed to realize the real-time location and observe the development of micro-damage on the surface of specimens. The accordance of calculation results and experimental results illustrates that the coupled strategy between DIC and Daubechies wavelet method is powerful in the real-time location of micro-damage on the concrete structure. The findings of this study could provide an effective and feasible method for structural health monitoring.