{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T15:13:35Z","timestamp":1784301215029,"version":"3.55.0"},"reference-count":24,"publisher":"MDPI AG","issue":"23","license":[{"start":{"date-parts":[[2020,12,4]],"date-time":"2020-12-04T00:00:00Z","timestamp":1607040000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["51678202"],"award-info":[{"award-number":["51678202"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["51378157"],"award-info":[{"award-number":["51378157"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100012166","name":"National key research and development program of China","doi-asserted-by":"publisher","award":["2017YFF0108702"],"award-info":[{"award-number":["2017YFF0108702"]}],"id":[{"id":"10.13039\/501100012166","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Structural damage generally initiates in the form of structural cracks. Thus, developing efficient crack detection techniques is of great importance for the structural health monitoring. In this paper, a new crack identification method is proposed, which is based on the differential pulse-width pair Brillouin optical time domain analysis (DPP-BOTDA) technology and the irregular features of Brillouin gain spectrum (BGS) in the fiber due to structural cracks. The proposed method provides a new way to detect and quantify structural cracks without knowing the strain in the structure. First, the working mechanism of DPP-BOTDA is introduced to illustrate the reason that the DPP-BOTDA, compared to traditional BOTDA technique, can significantly improve the spatial resolution of distributed strain sensing, which is critical for structural crack detection. Then, the BGSs in the fiber with the presence of structural cracks, measured by the DPP-BOTDA, are numerically simulated, from which the crack-induced irregular features of the BGS are summarized. Based these irregular features, new structural crack detection and quantification methods are proposed, which are found to be independent of structural stain. Finally, an experiment is conducted on a simple supported reinforced concrete (RC) beam. The results demonstrate that by using the BGS measured by the DPP-BOTDA, the proposed structural crack identification method successfully detects the occurrence of structural cracks and relatively accurately predicts the crack widths.<\/jats:p>","DOI":"10.3390\/s20236947","type":"journal-article","created":{"date-parts":[[2020,12,7]],"date-time":"2020-12-07T21:37:42Z","timestamp":1607377062000},"page":"6947","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Structural Crack Detection Using DPP-BOTDA and Crack-Induced Features of the Brillouin Gain Spectrum"],"prefix":"10.3390","volume":"20","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2286-5411","authenticated-orcid":false,"given":"Dongyu","family":"Zhang","sequence":"first","affiliation":[{"name":"Key Lab of Structures Dynamic Behavior and Control, Ministry of Education, Harbin Institute of Technology, Harbin 150090, China"},{"name":"School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yang","family":"Yang","sequence":"additional","affiliation":[{"name":"Key Lab of Structures Dynamic Behavior and Control, Ministry of Education, Harbin Institute of Technology, Harbin 150090, China"},{"name":"School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jinlong","family":"Xu","sequence":"additional","affiliation":[{"name":"Hongfeng Control Technology Co., Ltd. of Hubei Sanjiang Aerospace Group, Xiaogan 432100, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Li","family":"Ni","sequence":"additional","affiliation":[{"name":"Key Lab of Structures Dynamic Behavior and Control, Ministry of Education, Harbin Institute of Technology, Harbin 150090, China"},{"name":"School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9198-3951","authenticated-orcid":false,"given":"Hui","family":"Li","sequence":"additional","affiliation":[{"name":"Key Lab of Structures Dynamic Behavior and Control, Ministry of Education, Harbin Institute of Technology, Harbin 150090, China"},{"name":"School of Civil Engineering, Harbin Institute of Technology, Harbin 150090, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,4]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"13","DOI":"10.1016\/j.ultras.2018.06.008","article-title":"Lamb waves and electro-mechanical impedance based damage detection using a mobile PZT transducer set","volume":"92","author":"Zheng","year":"2019","journal-title":"Ultrasonics"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"115","DOI":"10.1080\/15502287.2019.1569174","article-title":"Sub-Structural Parameter Identification Including Cracks of Beam Structure Using PZT Patch","volume":"20","author":"Jinesh","year":"2019","journal-title":"Int. J. Comput. Methods Eng. Sci. Mech."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Hea, M., Lib, J., Zhang, Y., and Lia, W. (2020). Research on crack visualization method for dynamic detection of eddy current thermography. NDT E Int., 116.","DOI":"10.1016\/j.ndteint.2020.102361"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"199","DOI":"10.1016\/j.eng.2018.11.030","article-title":"Advances in Computer Vision-Based Civil Infrastructure Inspection and Monitoring","volume":"5","author":"Spencer","year":"2019","journal-title":"Engineering"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"787","DOI":"10.1364\/OL.22.000787","article-title":"Temperature and strain dependence of the power level and frequency of spontaneous Brillouin scattering in optical fibers","volume":"22","author":"Parker","year":"1997","journal-title":"Opt. Lett."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"552","DOI":"10.1364\/OL.18.000552","article-title":"22-km distributed temperature sensor using Brillouin gain in an optical fiber","volume":"18","author":"Bao","year":"1993","journal-title":"Opt. Lett."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"758","DOI":"10.1364\/OL.21.000758","article-title":"Simple distributed fiber sensor based on Brillouin gain spectrum analysis","volume":"21","author":"Nikles","year":"1996","journal-title":"Opt. Lett."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1161","DOI":"10.1109\/JLT.2011.2170813","article-title":"Extending the sensing range of Brillouin optical time-domain analysis combining frequency-division multiplexing and in-line EDFAs","volume":"30","author":"Dong","year":"2012","journal-title":"J. Lightwave Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"843","DOI":"10.1088\/0964-1726\/16\/3\/034","article-title":"The strain field method for structural damage identification using Brillouin optical fiber sensing","volume":"16","author":"Zhang","year":"2007","journal-title":"Smart Mater. Struct."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1061\/(ASCE)ST.1943-541X.0000795","article-title":"Damage Identification in Reinforced Concrete Beams Using Spatially Distributed Strain Measurements","volume":"139","author":"Goldfeld","year":"2013","journal-title":"J. Struct. Eng."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1797","DOI":"10.1061\/(ASCE)EM.1943-7889.0000622","article-title":"Theoretical and Experimental Investigations into Crack Detection with BOTDR-Distributed Fiber Optic Sensors","volume":"139","author":"Feng","year":"2013","journal-title":"J. Eng. Mech."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Deif, A., P\u00e9rez, B.M., Cousin, B., Zhang, C., Bao, X., and Li, W. (2010). Detection of cracks in a reinforced concrete beam using distributed Brillouin fibre sensors. Smart Mater Struct., 19.","DOI":"10.1088\/0964-1726\/19\/5\/055014"},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Liu, Y., and Zhang, S.Y. (2018). Damage Localization of Beam Bridges Using Quasi-Static Strain Influence Lines Based on the BOTDA Technique. Sensors, 18.","DOI":"10.3390\/s18124446"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Li, F., Zhao, W., Xu, H., Wang, S., and Du, Y. (2019). A Highly Integrated BOTDA\/XFG Sensor on a Single Fiber for Simultaneous Multi-Parameter Monitoring of Slopes. Sensors, 19.","DOI":"10.3390\/s19092132"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Kishida, K., Li, C.H., and Nishiguchi, K. (2005, January 23\u201327). Pulse pre-pump method for cm-order spatial resolution of BOTDA. Proceedings of the 17th International Conference on Optical Fibre Sensors, Bruges, Belgium.","DOI":"10.1117\/12.624259"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"9782","DOI":"10.1364\/AO.55.009782","article-title":"Interference and differentiation of the neighboring surface microcracks in distributed sensing with PPP-BOTDA","volume":"55","author":"Meng","year":"2016","journal-title":"Appl. Opt."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"4972","DOI":"10.1364\/AO.54.004972","article-title":"Detection and monitoring of surface micro-cracks by PPP-BOTDA","volume":"54","author":"Meng","year":"2015","journal-title":"Appl. Opt."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Xu, J., Dong, Y., and Li, H. (2014). Research on fatigue damage detection for wind turbine blade based on high-spatial-resolution DPP-BOTDA. Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2014, Proceedings of the SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, San Diego, CA, USA, 10\u201313 March 2014, SPIE.","DOI":"10.1117\/12.2044840"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1229","DOI":"10.1364\/AO.51.001229","article-title":"2 cm spatial-resolution and 2 km range Brillouin optical fiber sensor using a transient differential pulse pair","volume":"51","author":"Dong","year":"2012","journal-title":"Appl. Opt."},{"key":"ref_20","unstructured":"Xue, J. (2019). High-Performance Distributed Fiber Optic Monitoring and Condition Assessment Methods for Infrastructure. [Ph.D Thesis, Harbin Institute of Technology]. School of Civil Engineering."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1340","DOI":"10.1109\/50.400678","article-title":"Experimental and theoretical studies on a distributed temperature sensor based on Brillouin scattering","volume":"13","author":"Bao","year":"1995","journal-title":"J. Lightwave Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"385","DOI":"10.1061\/(ASCE)0733-9399(1998)124:4(385)","article-title":"Mechanics of bond and interface shear transfer in optical fiber sensors","volume":"124","author":"Ansari","year":"1998","journal-title":"J. Eng. Mech. ASCE"},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Wan, K.T., Leung, C.K.Y., and Olson, N.G. (2008). Investigation of the strain transfer for surface-attached optical fiber strain sensors. Smart Mater. Struct., 17.","DOI":"10.1088\/0964-1726\/17\/3\/035037"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"297","DOI":"10.1093\/biomet\/76.2.297","article-title":"Regression and time series model selection in small samples","volume":"76","author":"Hurvich","year":"1989","journal-title":"Biometrika"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/23\/6947\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:41:43Z","timestamp":1760179303000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/23\/6947"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,12,4]]},"references-count":24,"journal-issue":{"issue":"23","published-online":{"date-parts":[[2020,12]]}},"alternative-id":["s20236947"],"URL":"https:\/\/doi.org\/10.3390\/s20236947","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,12,4]]}}}