Laboratory investigation of early damage detection for an old-aged reinforced concrete beam using acoustic emission and digital image correlation

Abstract

This paper presents an experimental study investigating the actual mechanical performance of a full-scale reinforced concrete beam that served for 60 years in an industrial environment. The primary objective is to verify early damage detection performance using acoustic emission (AE) and digital image correlation (DIC) methods based on the four-point bending test. Parameter analysis of AE provides an accurate indication of the crack opening process, especially for the early damage stage, while RA (rise time divided by amplitude) against AF (Acoustic counts divided by durable time) and b-value analyses based on AE parameters also provide specific damage propagation results for different load stages. Furthermore, owing to the good full-field measurement resolution of DIC, the strain results in each load stage more clearly present the crack pattern and distribution before the visible crack is found, and the results of the displacement derived from DIC images also capture the global and local deformation of the beam with satisfactory accuracy compared with conventional methods. A brief summary of the advantages and disadvantages of using AE and DIC for early damage detection of the full-scale beam is also provided. It is concluded that AE and DIC both exhibit good feasibility for early damage detection from the respective interior and exterior aspects. Robust signal and image processing algorithms can be integrated with these two methods for further quantitative analysis.