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

Hao Cheng*, Cornelis Weemstra, Max A.N. Hendriks, Yuguang Yang

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

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.

Original languageEnglish
Article number105221
Number of pages19
JournalAutomation in Construction
Volume158
DOIs
Publication statusPublished - 2023

Keywords

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

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