Continuous wave measurements in a network of transducers for structural health monitoring of a large concrete floor slab

Fröjd, Patrik; Ulriksen, Peter

doi:10.1177/1475921716642139

Cited by 16 publications

(20 citation statements)

References 26 publications

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“…When using networks of transducers, localization of changes is possible up to a certain extent. While most approaches are complex and computationally intensive [ 6 , 7 ], simplified techniques have been proposed [ 8 ]. In this paper, we show a very simple alternative.…”

Section: Introductionmentioning

confidence: 99%

Processing Ultrasonic Data by Coda Wave Interferometry to Monitor Load Tests of Concrete Beams

Niederleithinger

Wang

Herbrand

et al. 2018

Sensors

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Ultrasonic transmission measurements have been used for decades to monitor concrete elements, mostly on a laboratory scale. Recently, coda wave interferometry (CWI), a technique adapted from seismology, was introduced to civil engineering experiments. It can be used to reveal subtle changes in concrete laboratory samples and even large structural elements without having a transducer directly at the place where the change is taking place. Here, several load tests until failure on large posttensioned concrete beams have been monitored using networks of embedded transducers. To detect subtle effects at the beginning of the experiments and cope with severe changes due to cracking close to failure, the coda wave interferometry procedures had to be modified to an adapted step-wise approach. Using this methodology, we were able to monitor stress distribution and localize large cracks by a relatively simple technique. Implementation of this approach on selected real structures might help to make decisions in infrastructure asset management.

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Section: Introductionmentioning

confidence: 99%

Processing Ultrasonic Data by Coda Wave Interferometry to Monitor Load Tests of Concrete Beams

Niederleithinger

Wang

Herbrand

et al. 2018

Sensors

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“…In previous work, we have shown that similar damage can easily be detected with such 50-kHz continuous-wave measurements, viewing either amplitude or phase, in static environmental conditions. 13 The variations caused by the EOV are also illustrated in Figure 5(a) to (g), which shows the resulting images from the tomography procedure for a few select times using only the 50 kHz phase measurements. The gray scale corresponds to the deviations from the mean of the baseline data set, expressed in the number of standard deviations of the baseline set (averaged over the grid boxes in the tomography).…”

Section: Resultsmentioning

confidence: 98%

“…The monitoring system consisted of a distributed network of piezoelectric transducers which were used to transmit or receive continuous waves on command. The monitoring system is the same as used in our previously published work, 13 where it was shown to successfully detect damage in short-term acquisitions, where the data were not significantly affected by EOVs. The same localization procedure was applied here.…”

Section: Introductionmentioning

confidence: 99%

Detecting damage events in concrete using diffuse ultrasound structural health monitoring during strong environmental variations

Fröjd

Ulriksen

2017

Structural Health Monitoring

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Diffuse ultrasonic wave measurements used in structural health monitoring applications can detect damage in concrete. However, the accuracy is very susceptible to environmental variations. In this study, a large concrete floor slab was monitored using diffuse wave fields that were generated by continuous-wave transmissions between ultrasonic transducers. The slab was monitored for several weeks while being subjected to changes in environmental conditions. Subsequently, it was damaged using impact hits, resulting in centimeter-scale cracking. The variations caused by the environment masked the effects of the damage in the measurements. To address this issue, the Mahalanobis distance was used to distinguish between the influence of the damage and the influence of the environmental variations. The Mahalanobis model uses amplitude and phase measurements of continuous waves at a set of different frequencies as inputs. A moving window approach was applied to the baseline data set to account for slow trends. This study shows that this technique greatly suppresses most of the variations caused by environmental conditions. All damage events in our data set have been detected.

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“…These features are well-known to severely affect the performance of traditional direct wave-based techniques. Fortunately, previous studies in the fields of optics, acoustic, and geophysics demonstrate that noise-like coda waves contain detailed information about internal structures, and they are very sensitive to changes occurring in the large volume of a medium [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. This sensitivity is attributed to the fact that coda waves propagate following complex trajectories not limited to the direct path between two sensors, and they may traverse the regions of interest repeatedly.…”

Section: Introductionmentioning

confidence: 99%

Condition Evaluation of an Existing T-Beam Bridge Based on Neutral Axis Variation Monitored with Ultrasonic Coda Waves in a Network of Sensors

Zhan

Jiang

Zhang

et al. 2020

Sensors

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Neutral axis passing through the stiffness centroid of a structure is correlated with structural health conditions. Traditional techniques rely on gauge arrays to observe strains at their installation positions, and then locate a neutral axis through the intercept of the strain diagram. However, these localization results will be severely deviated if any damages exist among gauges or inside structures. In this paper, a novel technique is proposed to locate the neutral axis by measuring and analyzing ultrasonic coda waves in a network of transducers. Because of multiple trajectories, coda waves are sensitive to minor changes in a large volume of media that are not limited to direct paths between sensors. This technique is not only capable of locating a neutral axis with great efficiency and accuracy, but can also indicate global structural health and inner damages. The applicability of the technique is demonstrated by monitoring a 30 m concrete T-beam subjected to four-point loading tests. With an array of transducers placed at the surface, the neutral axes in the large region are located. The localization results also show clear trends that the global neutral axis moves up as the loads increase, which indicates the beam contains certain degrees of inner damage.

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Continuous wave measurements in a network of transducers for structural health monitoring of a large concrete floor slab

Cited by 16 publications

References 26 publications

Processing Ultrasonic Data by Coda Wave Interferometry to Monitor Load Tests of Concrete Beams

Processing Ultrasonic Data by Coda Wave Interferometry to Monitor Load Tests of Concrete Beams

Detecting damage events in concrete using diffuse ultrasound structural health monitoring during strong environmental variations

Condition Evaluation of an Existing T-Beam Bridge Based on Neutral Axis Variation Monitored with Ultrasonic Coda Waves in a Network of Sensors

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