Single micro-damage identification and evaluation in concrete using digital image correlation technology and wavelet analysis

Abstract

This work presents a coupled strategy between two-dimensional digital image correlation (2D-DIC) technology and wavelet packet analysis method to identify the location and development of concrete damage at an early stage. Three-point bending tests of plain concrete were carried out under quasi-static loading, and the image information of the specimen under different loads was collected by a charge-coupled device (CCD) camera. Subsequently, the collected images were analyzed by 2D-DIC to obtain strain contours under each load level, following which, Daubechies wavelet with two layers, 16 frequency bands, and order N of 16 was applied to investigate the energy spectrum of the specimen. In this way, micro-damage in concrete was characterized respectively by full-field and partial-field identification method for comparison. Result reveals that the partial-field identification method can orientate the micro-damage earlier and more correct than the full-field identification method, making it possible to achieve real-time measurement in concrete structures. Also, it is indicated that the finer blocks in the partial-field identification method cause a large energy change rate, which provides the capability for timely and accurate micro-damage identification.