Applications of Stretching Technique and Time Window Effects on Ultrasonic Velocity Monitoring in Concrete

Zhong, Bibo; Zhu, Jinying

doi:10.3390/app12147130

Cited by 15 publications

(6 citation statements)

References 39 publications

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“…These curves could serve as the basis for translation of multidimensional fields of velocity variations into stress changes and damage, even for more-than-one-dimensional stress states and on larger specimen scales beyond our investigations. We calculated the relation between velocity variation of the full-length ultrasonic signals for both uniaxial compression and uniaxial tension using a linear regression for elastic material behavior up to 30% of the respective stress which agrees with previous studies [ 4 , 6 , 27 ]. Furthermore, we evaluated shrinkage and creep processes equally by means of

and

to indicate long-term changes to the ultrasonic signals.…”

Section: Discussionsupporting

confidence: 84%

“…Reinforced concrete, however, poses a special challenge for NDT techniques due to the material’s heterogeneity, which complicates the separation between naturally present scatterers and undesired material changes, or damage. To this end, the evaluation of ultrasonic signals by means of Coda Wave Interferometry (CWI) is a promising and exceptionally sensitive method to detect even weak changes in the material and has been subject to previous studies on both the laboratory [ 2 , 3 , 4 , 5 , 6 ], and the structural scale [ 7 , 8 , 9 , 10 ]. It is suitable for application as a permanent monitoring system with the focus on the early warning of microcrack initiation, and possibly providing the impulse for further in-depth inspections at alarming locations.…”

Section: Introductionmentioning

confidence: 99%

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Impact of External Mechanical Loads on Coda Waves in Concrete

et al. 2022

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During their life span, concrete structures interact with many kinds of external mechanical loads. Most of these loads are considered in advance and result in reversible deformations. Nevertheless, some of the loads cause irreversible, sometimes unnoticed changes below the macroscopic scale depending on the type and dimension of the impact. As the functionality of concrete structures is often relevant to safety and society, their condition must be known and, therefore, assessed on a regular basis. Out of the spectrum of non-destructive monitoring methods, Coda Wave Interferometry using embedded ultrasonic sensors is one particularly sensitive technique to evaluate changes to heterogeneous media. However, there are various influences on Coda waves in concrete, and the interpretation of their superimposed effect is ambiguous. In this study, we quantify the relations of uniaxial compression and uniaxial tension on Coda waves propagating in normal concrete. We found that both the signal correlation of ultrasonic signals as well as their velocity variation directly reflect the stress change in concrete structures in a laboratory environment. For the linear elastic range up to 30% of the strength, we calculated a velocity variation of −0.97‰/MPa for compression and 0.33%/MPa for tension using linear regression. In addition, these parameters revealed even weak irreversible changes after removal of the load. Furthermore, we show the time-dependent effects of shrinkage and creep on Coda waves by providing the development of the signal parameters over time during half a year together with creep recovery. Our observations showed that time-dependent material changes must be taken into account for any comparison of ultrasonic signals that are far apart in time. The study’s results demonstrate how Coda Wave Interferometry is capable of monitoring stress changes and detecting even small-size microstructural changes. By indicating the stated relations and their separation from further impacts, e.g., temperature and moisture, we anticipate our study to contribute to the qualification of Coda Wave Interferometry for its application as an early-warning system for concrete structures.

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and

to indicate long-term changes to the ultrasonic signals.…”

Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Impact of External Mechanical Loads on Coda Waves in Concrete

et al. 2022

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“…Therefore, the window [0.05, 0.15 ms] of the P-wave part is used for the wave velocity change analysis using the stretching technique. 30…”

Section: Signal Processing For Wave Velocity Analysismentioning

confidence: 99%

“…Therefore, the window [0.05, 0.15 ms] of the P-wave part is used for the wave velocity change analysis using the stretching technique. 30 Niederleithinger and Wang et al 31,32 proposed the stepwise CWI method to calculate significant velocity changes in long-term monitoring data with large temperature variations. CWI is applied to each segment of slow-changing signals and changes the reference signal when the coherence drops below a certain threshold.…”

Section: Challenges With Cwimentioning

confidence: 99%

Long-term ultrasonic monitoring of concrete affected by alkali-silica reaction

Sun

Tang

Malone

et al. 2023

Structural Health Monitoring

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This article presents continuous monitoring results of alkali-silica reaction (ASR) development in concrete specimens for over 400 days using ultrasonic testing and expansion measurements. Eight concrete specimens with nonreactive aggregate (Control), reactive coarse aggregate, and reactive fine aggregates were cast with two reinforced confinement conditions. The specimens were conditioned in an environmental chamber with high temperature and humidity (38°C and 90% relative humidity) to accelerate the ASR development. A multichannel ultrasonic monitoring system was developed to collect ultrasonic signals automatically, and the expansions in three directions were measured periodically. Results showed that the relative velocity change could detect the ASR initiation in all reactive specimens and show a correlation with expansion in the early stage. However, these correlations are inconsistent for different ASR specimens, and the velocity change becomes less sensitive to ASR damage in the late stage (after 300 days). Irrecoverable velocity drop was observed during every chamber shutdown period, especially in specimens with higher levels of ASR damage. This phenomenon suggests that the nonlinear ultrasonic response caused by the ambient temperature variation may indicate the ASR damage.

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“…However, there have been limited studies on the direct judgment of the nondestructive evaluation (NDE) based on various criteria of numerous data. Most NDE studies have focused on determining and verifying the extent of concrete deterioration using single or multiple NDE methods [ 11 , 12 , 13 ]. Furthermore, the NDE methods have relied on various physical phenomena, such as ultrasonic, electrical, strain, and thermal, to identify specific indicators of the degradation process.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Applicability of the Impact-Echo Test Using Semi-Supervised Learning Based on Dynamic Preconditions

Yoon

Kim

2022

Sensors

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The Impact-Echo (IE) test is an effective method for determining the presence, depth, and area of cracks in concrete as well as the dimensions of the sound concrete without defects. In addition, shallow delamination can be measured by confirming a flexural mode in the low-frequency region. Owing to the advancement of non-contact sensors and automated measurement equipment, the IE test can be measured at multiple points in a short period. To analyze and distinguish a large volume of data, applying supervised learning (SL) associated with various contemporary algorithms is necessary. However, SL has limitations due to the difficulty in accurate labeling for increased volumes of test data, and reflection of new specimen characteristics, and it is necessary to apply semi-supervised learning (SSL) to overcome them. This study analyzes the accuracy and evaluates the applicability of a model trained with SSL rather than SL using the data from the air-coupled IE test based on dynamic preconditions. For the detection of delamination defects, the dynamic behavior-based flexural mode was identified, and 21 features were extracted in the time and frequency domains. Three principal components (PCs) such as the real moment, real RMS, and imaginary moment were derived through principal component analysis (PCA). PCs were identical in slab, pavement, and deck. In the case of SSL considering a dynamic behavior, the accuracy increased by 7–8% compared with SL, and it could categorize good, fair, and poor status to a higher level for actual structures. The applicability of SSL to the IE test was confirmed, and because the crack progress varies under field conditions, other parameters must be considered in the future to reflect this.

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Applications of Stretching Technique and Time Window Effects on Ultrasonic Velocity Monitoring in Concrete

Cited by 15 publications

References 39 publications

Impact of External Mechanical Loads on Coda Waves in Concrete

Impact of External Mechanical Loads on Coda Waves in Concrete

Long-term ultrasonic monitoring of concrete affected by alkali-silica reaction

A Study on the Applicability of the Impact-Echo Test Using Semi-Supervised Learning Based on Dynamic Preconditions

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