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Summary: Acoustic emission (AE) technology is extensively acknowledged as a promising structural health monitoring (SHM) approach; meanwhile, AE monitoring has long been criticised for a lack of quantitative results. This work revealed a strong correlation between the shear stress distribution and the resulting AE distribution, enabling accurate and real‐time quantification of the shear stress states in concrete beams using only AE measurements. This paper started by introducing the AE phenomenon and the theoretical distribution of the shear stresses on a beam cross section, which revealed that the distributions of the stresses and the resulting emissions inherently correlate to each other. Twelve reinforced concrete beams were then tested, deploying devices including an AE system. The results showed that the AE source intensity distribution strongly correlated with that of the shear stresses in a beam segment when the beam was in both the working stage and the failure phase and that the matching degree of these two distribution curves varied from 79.20% to 94.12%. The correlation revealed in the paper will boost a wide range of significant AE‐based scientific research and engineering applications, including SHM and non‐destructive testing. [ABSTRACT FROM AUTHOR]

Measuring stress is critical in the Civil Engineering. However, established acoustic emission-based techniques can hardly evaluate the stress level which a structure is experiencing. Accordingly, an idea of ‘listening’ to Acoustic Emission (AE) to evaluate critical stress states in reinforced concrete (RC) beams is investigated here. Previous work found that the stress diagram of an RC beam cross section strongly correlates with the corresponding AE event intensity distribution pattern. Therefore, the stress level of this type of structures was estimated by utilising the remarkable correlation in this study. First of all, the stress diagrams of a cross section of an RC beam loaded to failure were analysed, revealing features which had close relations with the stress level of the section. Thanks to the correlation, these features were also extracted from the corresponding distribution patterns of the AE event intensity and then used to estimate the stress state. As a result, the AE Intensity Distribution (AID) analysis approach was developed. Data from an experiment conducted on six RC beams with a Digital Image Correlation (DIC) system and an AE device were adopted to verify the approach. Results showed that the indicators of the approach strongly correlated with the stress levels of the specimens; that the approach can characterise the stress states precisely, with an error of about five per cent in critical stages. Besides the approach, more profound significance of this work lies in that it demonstrated the great capability of an innovative strategy, namely characterising structural behaviours accurately via correlating an AE distribution pattern with the corresponding stress diagram. [ABSTRACT FROM AUTHOR]

Two established techniques for monitoring concrete under loading are Acoustic Emission (AE) and strain gauges. The distribution of strain, along with that of stress, on a beam cross section is well established both theoretically and experimentally. However, the AE distribution through the depth of the cross section has received little attention previously. In addition, the correlation between the AE distribution and that of stress on the section could provide valuable insight into the condition of a structure. Therefore, these topics are experimentally addressed in this article. Specifically, six Reinforced Concrete (RC) beams were tested. AE and Digital Image Correlation (DIC) were employed to monitor the beams during loading. Finally, the AE and stress distributions were analysed. The results showed that AE parameters are capable of characterising behaviours of RC beams in the depth direction. Furthermore, the distribution of AE events strongly correlated with that of compressive stress, especially in the post-reinforcement yielding stage. According to these findings, it is highly possible to estimate stress levels of RC beam structures in engineering and science by adopting the AE technique. [ABSTRACT FROM AUTHOR]

• The stress distribution in the concrete joints of girder structures is targeted. • The relationship between the stress distribution and the resulting acoustic-emission distribution is studied. • The intensity of acoustic-emission events is found to be correlated closely with the stress. • Both the Kaiser effect and a stress threshold influence the relationship appreciably. The stresses in concrete joints connecting adjacent girders are crucially important for the load-transfer mechanism of these structures but to date have been very difficult to measure. In the present study, an experimental investigation is performed to explore the relationship between the stress distribution and the variation of the resulting acoustic emissions (AEs), which provides a fundamental basis for characterizing these stresses quantitatively. The present paper begins by introducing an analytical solution to the shear-stress distributions along the joints in a girder model. The aforementioned relationship is then explained based on the inherent connections among stress, damage, and AE. To verify the relationship, a reinforced-concrete specimen comprising multiple prefabricated girders connected by cast-in-place concrete joints is tested. The results show that (i) the distribution of the intensity of AE events is strongly correlated with the variation of the corresponding shear stresses in a concrete joint, (ii) a stress threshold is critical for the relationship to hold, and (iii) the Kaiser effect influences the relationship appreciably in two completely different ways. The main impact of the present work is that the relationship is a viable basis for follow-up studies of estimating the actual stresses in the concrete joints of prefabricated structures via AE measurements. [ABSTRACT FROM AUTHOR]