Damage assessment of reinforced concrete structures under elevated-amplitude cyclic loading using sentry values based on acoustic emission testing

This article reports the combined application of sentry value and the Gaussian Mixture Modeling (GMM) algorithm to study crack classification in reinforced concrete (RC) beams using acoustic emission (AE) testing. The AE generated from RC beam specimens subjected to elevated-amplitude cyclic loading was used to study crack classification. The specimen approaches yielding, followed by a structural failure, when AE hits linked with shear cracks begin to exceed AE hits associated with tensile cracks. The sentry value for RC beam specimens decreased with subsequent higher amplitude loading phases, indicating the formation of macrocracks. The Kaiser effect phenomenon in RC beams was observed. The yielding of steel rebars and subsequent collapse of the RC beam specimens, followed by unstable crack propagation, were identified using the zero-slope line and a vertical spike in the sentry value versus the time graph. The current study appears to be significant for damage assessment and crack classification of in-situ RC flexural members.