Comparing the stretching technique and the wavelet cross-spectrum technique for measuring stress-induced wave-velocity changes in concrete

Comparing the stretching technique and the wavelet cross-spectrum technique for measuring stress-induced wave-velocity changes in concrete

Cheng, H. (TU Delft Concrete Structures)
Weemstra, C. (TU Delft Applied Geophysics and Petrophysics)
Hendriks, M.A.N. (TU Delft Concrete Structures; Norwegian University of Science and Technology (NTNU))
Yang, Y. (TU Delft Concrete Structures)

2023

Coda wave interferometry (CWI) holds promise as a technique for concrete stress monitoring. This is because the coda, which consists of multiply scattered arrivals, is the result of propagation through the medium over large distances. As such, it is sensitive to both minute structural changes and small velocity changes in that medium. Previous studies focusing on concrete have predominantly utilized the time-domain-based stretching technique to measure travel-time changes. There is, however, a lack of consensus on how to quantify these changes effectively. In this study, we conduct a systematic comparison between two techniques, namely the stretching technique and the wavelet cross-spectrum (WCS) technique, for measuring stress-induced velocity changes in a cylindrical concrete sample. Our comparison focuses on two key aspects: (i) stability against cycle skipping and (ii) consistency in retrieving velocity changes. Experimental results reveal that both the WCS technique and the stretching technique yield consistent velocity changes. In terms of stability, it is challenging to determine which technique performs better, due to differences in the mechanisms triggering cycle skipping. However, when considering waves with frequencies ranging from 50 kHz to 80 kHz, both techniques exhibit comparable performance. Based on our findings, we offer the following recommendations for utilizing these CWI techniques in concrete stress monitoring: For the stretching technique, selecting the time window length based on the wave frequency and the expected magnitude of velocity change. For the WCS technique, operating it in the frequency band where spectral decomposition shows sufficiently high energy in the signal and can accommodate the expected magnitude of velocity change.

Coda wave interferometry
Concrete
Smart aggregates
Stress-induced wave-velocity change
Stretching technique
Wavelet Cross-Spectrum (WCS) technique

http://resolver.tudelft.nl/uuid:429674e0-f2e7-4aa8-9ad2-e9fb6295ae59

https://doi.org/10.1016/j.autcon.2023.105221

0926-5805

Automation in Construction, 158

Institutional Repository

journal article

© 2023 H. Cheng, C. Weemstra, M.A.N. Hendriks, Y. Yang