{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T21:33:20Z","timestamp":1776288800252,"version":"3.50.1"},"reference-count":39,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2022,7,6]],"date-time":"2022-07-06T00:00:00Z","timestamp":1657065600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Federal Highway Administration (FHWA) Transportation Pooled Fund Study","award":["TPF-5(449)"],"award-info":[{"award-number":["TPF-5(449)"]}]},{"name":"Departments of Transportation of Iowa, Kansas, South Carolina, and North Carolina","award":["TPF-5(449)"],"award-info":[{"award-number":["TPF-5(449)"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper presents a field implementation of the structural health monitoring (SHM) of fatigue cracks for steel bridge structures. Steel bridges experience fatigue cracks under repetitive traffic loading, which pose great threats to their structural integrity and can lead to catastrophic failures. Currently, accurate and reliable fatigue crack monitoring for the safety assessment of bridges is still a difficult task. On the other hand, wireless smart sensors have achieved great success in global SHM by enabling long-term modal identifications of civil structures. However, long-term field monitoring of localized damage such as fatigue cracks has been limited due to the lack of effective sensors and the associated algorithms specifically designed for fatigue crack monitoring. To fill this gap, this paper proposes a wireless large-area strain sensor (WLASS) to measure large-area strain fatigue cracks and develops an effective algorithm to process the measured large-area strain data into actionable information. The proposed WLASS consists of a soft elastomeric capacitor (SEC) used to measure large-area structural surface strain, a capacitive sensor board to convert the signal from SEC to a measurable change in voltage, and a commercial wireless smart sensor platform for triggered-based wireless data acquisition, remote data retrieval, and cloud storage. Meanwhile, the developed algorithm for fatigue crack monitoring processes the data obtained from the WLASS under traffic loading through three automated steps, including (1) traffic event detection, (2) time-frequency analysis using a generalized Morse wavelet (GM-CWT) and peak identification, and (3) a modified crack growth index (CGI) that tracks potential fatigue crack growth. The developed WLASS and the algorithm present a complete system for long-term fatigue crack monitoring in the field. The effectiveness of the proposed time-frequency analysis algorithm based on GM-CWT to reliably extract the impulsive traffic events is validated using a numerical investigation. Subsequently, the developed WLASS and algorithm are validated through a field deployment on a steel highway bridge in Kansas City, KS, USA.<\/jats:p>","DOI":"10.3390\/s22145076","type":"journal-article","created":{"date-parts":[[2022,7,6]],"date-time":"2022-07-06T21:15:52Z","timestamp":1657142152000},"page":"5076","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":35,"title":["Structural Health Monitoring of Fatigue Cracks for Steel Bridges with Wireless Large-Area Strain Sensors"],"prefix":"10.3390","volume":"22","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3217-0907","authenticated-orcid":false,"given":"Sdiq Anwar","family":"Taher","sequence":"first","affiliation":[{"name":"Department of Civil, Environmental and Architectural Engineering, The University of Kansas, Lawrence, KS 66045, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3439-7539","authenticated-orcid":false,"given":"Jian","family":"Li","sequence":"additional","affiliation":[{"name":"Department of Civil, Environmental and Architectural Engineering, The University of Kansas, Lawrence, KS 66045, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9172-2524","authenticated-orcid":false,"given":"Jong-Hyun","family":"Jeong","sequence":"additional","affiliation":[{"name":"Department of Civil, Architectural Engineering and Mechanics, The University of Arizona, Tucson, AZ 85721, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0601-9664","authenticated-orcid":false,"given":"Simon","family":"Laflamme","sequence":"additional","affiliation":[{"name":"Department of Civil, Construction and Environmental Engineering, Iowa State University, Ames, IA 50011, USA"},{"name":"Department of Electrical and Computer Engineering, Iowa State University, Ames, IA 50011, USA"}]},{"given":"Hongki","family":"Jo","sequence":"additional","affiliation":[{"name":"Department of Civil, Architectural Engineering and Mechanics, The University of Arizona, Tucson, AZ 85721, USA"}]},{"given":"Caroline","family":"Bennett","sequence":"additional","affiliation":[{"name":"Department of Civil, Environmental and Architectural Engineering, The University of Kansas, Lawrence, KS 66045, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2835-6389","authenticated-orcid":false,"given":"William N.","family":"Collins","sequence":"additional","affiliation":[{"name":"Department of Civil, Environmental and Architectural Engineering, The University of Kansas, Lawrence, KS 66045, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5524-2416","authenticated-orcid":false,"given":"Austin R. J.","family":"Downey","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208, USA"},{"name":"Department of Civil and Environmental Engineering, University of South Carolina, Columbia, SC 29208, USA"}]}],"member":"1968","published-online":{"date-parts":[[2022,7,6]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Taher, S.A., Li, J., Collins, W., and Bennett, C. (2019, January 10\u201312). UAV-Based Non-Contact Fatigue Crack Monitoring of Steel Structures. Proceedings of the 12th International Workshop on Structural Health Monitoring (IWSHM), Stanford, CA, USA.","DOI":"10.12783\/shm2019\/32477"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"89","DOI":"10.1061\/(ASCE)1076-0342(2008)14:1(89)","article-title":"Design and implementation of scalable wireless sensor network for structural monitoring","volume":"14","author":"Pakzad","year":"2008","journal-title":"J. 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