Damage Mechanism Evaluation of Large-Scale Concrete Structures Affected by Alkali-Silica Reaction Using Acoustic Emission

Abstract

Alkali-silica reaction has caused damage to concrete structures, endangering structural serviceability and integrity. This is of concern in sensitive structures such as nuclear power plants. In this study, acoustic emission (AE) was employed as a structural health monitoring strategy in large-scale, reinforced concrete specimens affected by alkali-silica reaction with differing boundary conditions resembling the common conditions found in nuclear containments. An agglomerative hierarchical algorithm was utilized to classify the AE data based on energy-frequency based features. The AE signals were transferred into the frequency domain and the energies in several frequency bands were calculated and normalized to the total energy of signals. Principle component analysis was used to reduce feature redundancy. Then the selected principal components were considered as features in an input of the pattern recognition algorithm. The sensor located in the center of the confined specimen registered the largest portion of AE energy release, while in the unconfined specimen the energy is distributed more uniformly. This confirms the results of the volumetric strain, which shows that the expansion in the confined specimen is oriented along the thickness of the specimen.

Temporal Acoustic Emission Index for Damage Monitoring of RC Structures Subjected to Bidirectional Seismic Loadings

“…Firstly, the AE signals were filtered by a Swansong filter in order to avoid those of long duration and low amplitude, usually coming from the secondary mechanisms as mechanical friction. Table 2 lists the limit values previously proposed by Soltangharaei et al [22] for the RC structures with dimensions comparable to BS1 and BS2 for the Swansong filter. Basically, the filter eliminates the AE signals with a duration higher than DL, with DL depending on its amplitude as shown in Table 2.…”

“…During the works carried out by the Association of American Railroads [21] it was inferred that some secondary mechanisms like mechanical friction are characterized by the signals of long duration and low amplitude. This has resulted in the development of the Swansong filter technique [22], the variant of which was successfully used in this work. After the application of this filter, the evaluation of the acoustic energy emitted during each particular seismic event was analyzed.…”

Hsu-Nielsen source acoustic emission data on a concrete block

“…HLT is a lockout time, starting at the end of hit, during which the system does not response to threshold crossings. HDT is the time constant of the re-triggerable one-shot circuitry that determines the end of hit [3], [4].…”

Structural Health Monitoring of Large Structures Using Acoustic Emission–Case Histories

“…In applications aimed toward the SHM of concrete structures, the Ziehl group presented two studies [14,15]. In the first one, Abdelrahman et al [14] applied remote AE monitoring on an actively corroding concrete structure for one year and showed the feasibility of using AE for corrosion damage detection and classification.…”

“…Here, studies of decommissioned components and control concrete parts were examined in parallel and comparative evaluation led to the conclusion. In the second study, Soltangharaei et al [15] examined alkali-silicate reaction on large-scale concrete structures. They utilized an agglomerative hierarchical algorithm to classify the AE data based on energy-frequency based features.…”