{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,14]],"date-time":"2025-11-14T07:34:10Z","timestamp":1763105650912,"version":"build-2065373602"},"reference-count":28,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2019,6,5]],"date-time":"2019-06-05T00:00:00Z","timestamp":1559692800000},"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":["51875477","51475013"],"award-info":[{"award-number":["51875477","51475013"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Grouting ducts (containing steel strands) are widely used to increase the structural strengths of infrastructures. The determination of the steel strand\u2019s integrity inside of ducts and the grouting quality are important for a strength evaluation of the structure. In this study, a capacitive sensing technique was applied to identify the cross-sectional distribution of the steel strands. The distribution was expressed in polar coordinates in an external post-tensioned pre-stressed duct model. An improved capacitive sensor structure was designed, which consisted of four electrodes, and different electrode-pairs were used to determine various locations\u2019 information of the steel strands. Two rounds of measurements were conducted using the designed sensor to detect the angle (\u03b8) and center distance (r) of the steel strand in the duct. The simulated and experimental results are presented and analyzed. In general, it is difficult to locate the angle of a steel strand directly from first-round capacitance measurements by analyzing the experimental results. Our method based on Q-factor analysis was presented for the position detection of a steel bar in an external post-tensioned pre-stressed duct. The center distance of the steel bar could be identified by second-round capacitance measurements. The processed results verified the effectiveness of the proposed capacitive sensor structure. Thus, the capacitive sensing technique exhibited potential for steel strand cross-section distribution detection in external post-tensioned pre-stressed ducts.<\/jats:p>","DOI":"10.3390\/s19112564","type":"journal-article","created":{"date-parts":[[2019,6,6]],"date-time":"2019-06-06T03:38:01Z","timestamp":1559792281000},"page":"2564","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Detection of Single Steel Strand Distribution in Grouting Duct Based on Capacitive Sensing Technique"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3731-1518","authenticated-orcid":false,"given":"Nan","family":"Li","sequence":"first","affiliation":[{"name":"School of Automation, Northwestern Polytechnical University, Xi\u2019an 710071, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Mingchen","family":"Cao","sequence":"additional","affiliation":[{"name":"State Key Laboratory for Manufacturing Systems Engineering, Xi\u2019an Jiaotong University, Xi\u2019an 710049, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hangben","family":"Du","sequence":"additional","affiliation":[{"name":"School of Automation, Northwestern Polytechnical University, Xi\u2019an 710071, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cunfu","family":"He","sequence":"additional","affiliation":[{"name":"NDT&amp;E Research Centre, Beijing University of Technology, Beijing 100124, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bin","family":"Wu","sequence":"additional","affiliation":[{"name":"NDT&amp;E Research Centre, Beijing University of Technology, Beijing 100124, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,6,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1016\/S0963-8695(00)00035-9","article-title":"Ultrasonic tomography of grouted duct post-tensioned reinforced concrete bridge beams","volume":"34","author":"Martin","year":"2001","journal-title":"NDT E Int."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Jiang, T., Kong, Q., Wang, W., Huo, L., and Song, G. (2016). Monitoring of grouting compactness in a post-tensioning tendon duct using piezoceramic transducers. Sensors, 16.","DOI":"10.3390\/s16081343"},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Jiang, T., Zheng, J., Huo, L., and Song, G. (2017). Finite element analysis of grouting compactness monitoring in a post-tensioning tendon duct using piezoceramic transducers. Sensors, 17.","DOI":"10.3390\/s17102239"},{"key":"ref_4","first-page":"462","article-title":"Detecting voids in grouted tendon ducts of post-tensioned concrete structures using the impact-echo method","volume":"93","author":"Jaeger","year":"1996","journal-title":"Struct. J."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"388","DOI":"10.1007\/s12205-012-1295-0","article-title":"Non-destructive testing methods to identify voids in external post-tensioned tendons","volume":"16","author":"Im","year":"2012","journal-title":"KSCE J. Civ. Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1109\/JSEN.2012.2219392","article-title":"Capacitive Sensor for Measuring the Filled of Post-Tensioned Ducts. Experimental Setup, Modeling and Signal Processing","volume":"13","author":"Bore","year":"2013","journal-title":"IEEE Sens. J."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"110","DOI":"10.1016\/j.ndteint.2013.07.010","article-title":"Electromagnetic characterization of grouting materials of bridge post tensioned ducts for NDT using capacitive probe","volume":"60","author":"Bore","year":"2013","journal-title":"NDT E Int."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"26399","DOI":"10.1364\/OE.23.026399","article-title":"High-resolution extended source optical coherence tomography","volume":"23","author":"Yu","year":"2015","journal-title":"Opt. Express"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"88","DOI":"10.1016\/j.sna.2016.07.024","article-title":"A boundary detecting method for post-tensioned pre-stressed ducts based on Q-factor analysis","volume":"248","author":"Li","year":"2016","journal-title":"Sens. Actuators A-Phys."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"438","DOI":"10.1002\/stc.1586","article-title":"Corrosion monitoring of post-tensioned concrete structures using fractal analysis of guided ultrasonic waves","volume":"21","author":"Moustafa","year":"2014","journal-title":"Struct. Control Health Monit."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"184104","DOI":"10.1063\/1.4828556","article-title":"Magnetic mechanisms of magnetic flux leakage nondestructive testing","volume":"103","author":"Sun","year":"2013","journal-title":"Appl. Phys. Lett."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"123","DOI":"10.1016\/j.sna.2016.04.028","article-title":"Fiber Bragg grating based sensing system: Early corrosion detection for structural health monitoring","volume":"246","author":"Tan","year":"2016","journal-title":"Sens. Actuators A-Phys."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"24","DOI":"10.1016\/j.sna.2018.01.009","article-title":"Multi-source effect in magnetizing-based eddy current testing sensor for surface crack in ferromagnetic materials","volume":"271","author":"Deng","year":"2018","journal-title":"Sens. Actuators A-Phys."},{"key":"ref_14","unstructured":"Liu, X., Wang, Y., Wu, B., Gao, Z., and He, C. (2016). Design of tunnel magnetoresistive-based circular MFL sensor array for the detection of flaws in steel wire rope. J. Sens., 2016."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1016\/j.sna.2017.11.005","article-title":"A novel sensor to measure the biased pulse magnetic response in steel stay cable for the detection of surface and internal flaws","volume":"269","author":"Liu","year":"2018","journal-title":"Sens. Actuators A-Phys."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Zhang, X., Zhang, L., Liu, L., and Huo, L. (2018). Prestress monitoring of a steel strand in an anchorage connection using piezoceramic transducers and time reversal method. Sensors, 18.","DOI":"10.3390\/s18114018"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1016\/j.ymssp.2019.04.053","article-title":"Damage detection of anchored region on the messenger cable based on matching pursuit algorithm","volume":"130","author":"Hong","year":"2019","journal-title":"Mech. Syst. Signal Process."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1320","DOI":"10.1007\/s12205-019-0715-9","article-title":"Experimental Study on Corrosion of Unstressed Steel Strand based on Metal Magnetic Memory","volume":"23","author":"Xia","year":"2019","journal-title":"KSCE J. Civ. Eng."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Dang, N.L., Huynh, T.C., and Kim, J.T. (2019). Local Strand-Breakage Detection in Multi-Strand Anchorage System Using an Impedance-Based Stress Monitoring Method\u2014Feasibility Study. Sensors, 19.","DOI":"10.3390\/s19051054"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"662","DOI":"10.1007\/s11709-018-0512-4","article-title":"The defect-length effect in corrosion detection with magnetic method for bridge cables","volume":"12","author":"Zhang","year":"2018","journal-title":"Front. Struct. Civ. Eng."},{"key":"ref_21","unstructured":"Ministry of Housing and Urban-Rural Development of PRC (2015). The Quality Acceptance Specification for Concrete Structure Engineering Construction GB50204-2015."},{"key":"ref_22","unstructured":"Ministry of Housing and Urban-Rural Development of PRC (2014). External Prestressed Cable Technical Conditions GB\/T 30827-2014."},{"key":"ref_23","first-page":"52","article-title":"Bursting Crack Mechanism of Closure Segment Bottom Slab for the Certain Prestressed Variable Depth Box-section Bridge","volume":"30","author":"Lou","year":"2012","journal-title":"Sci. Technol. Rev."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"027119","DOI":"10.1063\/1.4866986","article-title":"Parallel double-plate capacitive proximity sensor modelling based on effective theory","volume":"4","author":"Li","year":"2014","journal-title":"AIP Adv."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"125401","DOI":"10.1088\/0957-0233\/25\/12\/125401","article-title":"Enhancing electrical capacitance tomographic sensor design using fuzzy theory based quantifiers","volume":"25","author":"Li","year":"2014","journal-title":"Meas. Sci. Technol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2074","DOI":"10.1109\/JSEN.2017.2664864","article-title":"Multi-parametric indicator design for ECT sensor optimization used in oil transmission","volume":"17","author":"Li","year":"2017","journal-title":"IEEE Sens. J."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"434","DOI":"10.1109\/JSEN.2006.870161","article-title":"Design principles for multichannel fringing electric field sensors","volume":"6","author":"Li","year":"2006","journal-title":"IEEE Sens. J."},{"key":"ref_28","unstructured":"Ministry of Housing and Urban-Rural Development of PRC (2015). Code for Application Technique of Cementitious Grout GB\/T50448-2015."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/11\/2564\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:56:19Z","timestamp":1760187379000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/11\/2564"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,6,5]]},"references-count":28,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2019,6]]}},"alternative-id":["s19112564"],"URL":"https:\/\/doi.org\/10.3390\/s19112564","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2019,6,5]]}}}