TY - GEN A1 - Reichel, D. A1 - Schreiner, U. A1 - Lindner, E. A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Barner, Daniel ED - Mencík, J. T1 - Strain Monitoring of a High Speed Railway Track Using Embedded Fibre-Optic Sensors T2 - First International Conference Reliability and Diagnostics of Transport Structures and Means CY - Pardubice, Czech Republic DA - 2002-09-26 PY - 2002 SN - 9788071944645 PB - Univ. CY - Pardubice AN - OPUS4-1725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Barner, Andreas A1 - Crail, S. A1 - Reichel, D. A1 - Schreiner, U. A1 - Lindner, E. T1 - Static and dynamic measurements on a newly developed precast concrete track for high speed railway traffic using embedded fiber-optic sensors T2 - International Conference on Force, Mass, Torque, Hardness and Civil Engineering Metrology in the Age Globalization CY - Celle, Germany DA - 2002-09-24 KW - Railway track system KW - Bonding behaviour KW - Fibre-optic sensor KW - Concrete composites PY - 2002 SN - 3-18-091685-0 SN - 0083-5560 N1 - Serientitel: VDI-Berichte – Series title: VDI-Berichte IS - 1685 SP - 147 EP - 152 PB - VDI-Verl. CY - Düsseldorf AN - OPUS4-1755 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Kohlhoff, Harald A1 - Knapp, Jürgen A1 - Brandes, Klaus A1 - Haenichen, H. A1 - Inaudi, D. ED - Inaudi, D. T1 - Complex measurement system for long-term monitoring of prestressed railway bridges of the new "Lehrter Bahnhof" in Berlin T2 - Smart structures and materials 2002 - Smart sensor technology and measurement systems CY - San Diego, CA, USA DA - 2002-03-18 KW - Fiber-optic sensors KW - Monitoring KW - Structure behaviour PY - 2002 SN - 0-8194-4442-1 DO - https://doi.org/10.1117/12.472624 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 4694 SP - 236 EP - 241 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-1456 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Brandes, Klaus A1 - Barner, Andreas A1 - Crail, S. A1 - Reichel, D. A1 - Schreiner, U. A1 - Ecke, W. ED - Inaudi, D. T1 - Strain monitoring of a newly developed precast concrete track for high speed railway traffic using embedded fiber-optic sensors KW - Railway track system KW - Bonding behaviour KW - Fiber-optic sensor KW - Concrete composites PY - 2002 SN - 0-8194-4442-1 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 4694 SP - 259 EP - 264 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-1457 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Gutmann, Toivo A1 - Basedau, Frank A1 - Molter, M. A1 - Hegger, J. ED - Inaudi, D. T1 - Characterization of bond performance of textiles in cement matrices using fiber optic sensors T2 - Smart structures and materials 2002 - Smart sensor technology and measurement systems CY - San Diego, CA, USA DA - 2002-03-18 KW - Textile reinforced concrete KW - Fibers KW - Concrete KW - Bond KW - Fiber-optic sensors PY - 2002 SN - 0-8194-4442-1 DO - https://doi.org/10.1117/12.472626 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 4694 SP - 253 EP - 258 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-1458 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hofmann, Detlef A1 - Habel, Wolfgang A1 - Gutmann, Toivo A1 - Basedau, Frank A1 - Molter, M. A1 - Hegger, J. A1 - Will, N. T1 - Untersuchungen an textilbewehrtem Beton PY - 2002 SN - 0025-5300 VL - 44 IS - 5 SP - 194 EP - 198 PB - Carl Hanser Verlag CY - München AN - OPUS4-1474 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Habel, Wolfgang A1 - Gloetzl, R. ED - López-Higuera, J. M. T1 - Lightning-safe diaphragm pressure gauge for geotechnical applications using a long-term reliable absolute EFPI sensor T2 - 2nd European Workshop on Optical Fibre Sensors ; 2nd EWOFS '04 CY - Santander, Spain DA - 2004-06-09 KW - Pressure sensor KW - Fibre Fabry-Pérot interferometer KW - Geotechnical application KW - Precise deformation measurement KW - Long-term stability PY - 2004 SN - 0-8194-5434-6 DO - https://doi.org/10.1117/12.566543 SN - 0038-7355 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 5502 SP - 128 EP - 131 PB - SPIE CY - Bellingham, Wash. AN - OPUS4-3844 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Basedau, Frank T1 - Rückwirkungsarme faseroptische Dehnungssensoren für weiche Materialien und Verbundwerkstoffe T2 - GESA-Symposium 1999 CY - Warnemünde, Deutschland DA - 1999-05-06 KW - Faseroptische Dehnungssensoren PY - 1999 SN - 3-18-091463-7 SN - 0083-5560 N1 - Sprachen: Deutsch/Englisch - Languages: German/English SP - 103 EP - 112 PB - VDI-Verl. CY - Düsseldorf AN - OPUS4-790 LA - mul AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Crail, S. A1 - Reichel, D. A1 - Schreiner, U. A1 - Lindner, E. A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Barner, Andreas ED - Casciati, F. T1 - Strain Monitoring of a High Speed Railway Track Using Embedded Fibre-Optic Sensors PY - 2003 SN - 0-471-48980-8 VL - 2 SP - 903 EP - 909 PB - Wiley CY - Chichester AN - OPUS4-2374 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schallert, Matthias A1 - Krebber, Katerina A1 - Hofmann, Detlef A1 - Habel, Wolfgang A1 - Stahlmann, J. T1 - Auswahl geeigneter Fasersensorprinzipien für Anwendungen in der Geotechnik T2 - Fachseminar "Messen in der Geotechnik 2004" CY - Braunschweig, Deutschland DA - 2004-09-09 PY - 2004 SN - 3-927610-68-2 N1 - Serientitel: Mitteilung des Instituts für Grundbau und Bodenmechanik - Technische Universität Braunschweig – Series title: Mitteilung des Instituts für Grundbau und Bodenmechanik - Technische Universität Braunschweig IS - 77 SP - 309 EP - 328 PB - Inst. für Grundbau und Bodenmechanik, Techn. Univ. CY - Braunschweig AN - OPUS4-4424 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kusche, Nadine A1 - Schukar, Vivien A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Habel, Wolfgang A1 - Woschitz, H. A1 - Lienhart, W. ED - Jaroszewicz, L.R. T1 - Field examples for optical fibre sensor condition diagnostics based on distributed fibre-optic strain sensing N2 - Fibre optic sensors for monitoring in safety-relevant structures have to be validated in order to proof their reliability under typical structural load conditions. The reliable use of optical fibre sensors depends strongly on an appropriate and qualitative application. Diagnostics of the physical condition of embedded and surface-applied fibre optic strain sensors are demonstrated on field examples. Distributed strain measurement based on Rayleigh backscattering is used to determine breakage of the fibre, interface adhesion problems and to identify application related strain transfer mechanisms. T2 - EWOFS 2013 - 5th European workshop on optical fibre sensors CY - Kraków, Poland DA - 19.05.2013 KW - Fibre Bragg grating KW - Rayleigh backscattering KW - Condition diagnostics KW - Strain KW - Strain transfer PY - 2013 SN - 978-0-81949-634-8 DO - https://doi.org/10.1117/12.2025567 SN - 0277-786X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 8794 IS - Paper 8794 - 181 SP - 879433-1 EP - 879433-4 AN - OPUS4-28570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - RPRT A1 - Hamann, M. A1 - Kubowitz, P. A1 - Habel, Wolfgang A1 - Hofmann, Detlef T1 - Hochleistungsholztragwerke - HHT - Entwicklung von hochbelastbaren Verbundbauweisen im Holzbau mit faserverstärkten Kunststoffen, technischen Textilien und Formpressholz - Aufstockung: Ersteinsatz von optischen Messfasern in Holzbauteilen KW - Holzbau KW - Hochleistungsholztragwerke KW - Verbundbauweise KW - Hybridbauteile KW - Faseroptische Sensorik KW - Faser-Bragg-Gitter KW - Optische Messverfahren KW - Monitoring KW - Brückenbau KW - Bauwerksüberwachung KW - Applizierungstechnologie PY - 2013 SN - 978-3-9815360-8-9 IS - BMBF-Vorhaben 0330722B SP - 1 EP - 103 PB - BAM Bundesanstalt für Materialforschung und -prüfung CY - Berlin AN - OPUS4-27958 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilder, Constanze A1 - Hofmann, Detlef A1 - Kohlhoff, Harald A1 - Habel, Wolfgang ED - Ramos, G. A. T1 - Structure-integrated fiber-optic strain wave sensor for concrete pile testing and monitoring N2 - Reinforced concrete piles are used in case of structures that are constructed on soft ground to transfer the loads into deeper strata with sufficient bearing capacity. In order to determine the pile’s behavior and possible damage, static and dynamic pile tests are carried out. Dynamic measurements taken from the pile head can show the bearing behavior and structural integrity by using the theory of wave propagation. In order to receive more precise information about the pile features, now, a string of sensors is embedded at different levels of the pile. A fiber optic strain wave sensor, based on the extrinsic Fabry-Perot interferometer (EFPI), has already been developed and tested in full-scale field tests by Schallert (2010). It was possible to detect the introduced deformation caused by the static load and the dilatational wave during dynamic loading. Although the full-scale tests were successful, the engineering design of the sensor body left room - from the economical point of view - to be optimized. After laboratory tests with the optimized sensor, a cast-in-situ bored pile has been built at the BAM Test Site Technical Safety in Horstwalde, South of Berlin. Additionally to the EFPI sensors, fiber Bragg grating (FBG) sensors, temperature sensors and resistance strain gauge (RSG) sensors are embedded in order to compare the signals with each other. In this paper, the modified sensor and the Setup of the cast-in-situ bored pile along with results of dynamic tests are shown. T2 - SHMII-5 - 5th International conference on structural health monitoring of intelligent infrastructure CY - Cancún, Mexico DA - 11.12.2011 KW - Fibre optic sensors KW - Monitoring KW - Concrete pile KW - Foundation KW - Integrity testing PY - 2011 IS - Topic_04.Cat_4.2-abs002 SP - 1 EP - 8 PB - National Autonomous University of Mexico CY - Mexico City AN - OPUS4-25142 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilder, Constanze A1 - Kohlhoff, Harald A1 - Hofmann, Detlef A1 - Habel, Wolfgang ED - Boller, C. T1 - Structure-integrated fibre-optic strain wave sensor for pile testing and monitoring of reinforced concrete piles T2 - EWSHM'12 - 6th European workshop on structural health monitoring 2012 CY - Dresden, Germany DA - 2012-07-03 PY - 2012 SN - 978-3-940283-41-2 VL - 1 SP - 523 EP - 530 CY - Berlin AN - OPUS4-26279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schallert, M. A1 - Hofmann, Detlef A1 - Habel, Wolfgang T1 - Strukturanalyse von Betonpfählen durch eingebettete faseroptische Sensoren N2 - Zur Gründung von Bauwerken auf weichen, gering tragfähigen Böden werden unter anderem Betonpfähle, einzeln oder in Pfahlgruppen, eingesetzt. Deren Bewertung bzgl. Tragverhalten bzw. Integrität ist bei bestimmten Baugrundverhältnissen und Pfahlgeometrien schwierig. Hierfür werden statische und dynamische Pfahlprüfungen durchgeführt. Aus Messwerten vom Pfahlkopf bzw. vom oberen Pfahlbereich werden üblicherweise die notwendigen Aussagen abgeleitet. Eine genauere Bewertung ist möglich, wenn präzise Messwerte über die gesamte Pfahllänge vorliegen. Deshalb wurden hochauflösende betoneinbettbare Messwertaufnehmer auf Basis von Faser-Fabry-Perot-Sensoren entwickelt, die in Modell- und in realen Rammpfählen getestet wurden. Der Beitrag beschreibt den Sensor, die Installation und exemplarisch einige Testergebnisse zur Erfassung der Wellenausbreitung im Modellpfahl. Feldtests wurden zurzeit der Erstellung des Manuskripts erfolgreich begonnen. Reinforced concrete piles are often used for structures on non-sufficiently bearing soil areas. Assessment of bearing capacity and bearing behaviour of large concrete piles remains a difficult task under specific soil conditions and pile geometries. Usually static and dynamic pile tests are carried out for quality assurance. From dynamic measurements taken only from the pile head, the bearing behaviour and structural integrity can be derived using the one-dimensional theory of wave propagation. More precise information about the pile features can be achieved by highly resolving fibre-optic sensors based on Fabry-Perot technology, distributed over several locations along the pile length. Small scale piles and real driven piles have been tested. This paper describes the sensor, the sensor installation, and experimental results of tests in laboratory as well as test results for recording the wave propagation in the small scale piles. KW - Eingebetteter faseroptischer Sensor KW - Fabry-Perot-Sensor KW - Tragverhalten KW - Integritätstest KW - Embedded fiber-optic sensor KW - Low-strain pile integrity tests PY - 2008 DO - https://doi.org/10.1524/teme.2008.0867 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 VL - 75 IS - 9 SP - 485 EP - 500 PB - Oldenbourg CY - München AN - OPUS4-18041 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Dantan, Nathalie A1 - Hofmann, Detlef A1 - Krebber, Katerina A1 - Schallert, Matthias T1 - Ausgewählte Anwendungsbeispiele faseroptischer Sensoren im Ingenieurbau und in der Geotechnik T2 - Ingenieurvermessung 07 CY - Graz, Österreich DA - 2007-04-17 PY - 2007 SP - 281 EP - 294 PB - Wichmann CY - Graz AN - OPUS4-14760 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Krebber, Katerina A1 - Dantan, Nathalie A1 - Schallert, Matthias A1 - Hofmann, Detlef ED - Bin Shi, T1 - Recent examples of applied fibre optic sensors in geotechnical areas to evaluate and monitor structural integrity T2 - OSMG-2007 - 2nd International Workshop on Opto-electronic Sensor-based Monitoring in Geo-engineering CY - Nanjing, China DA - 2007-10-18 KW - Fibre optic sensors KW - Monitoring KW - Geotechnique KW - Pile load test KW - pH sensor KW - Geotextile monitoring KW - Ground anchor monitoring KW - Distributed sensor PY - 2007 SP - 27 EP - 35 CY - Nanjing, China AN - OPUS4-16431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef T1 - Internationale und nationale Normen und Richtlinien für faseroptische Komponenten und Messverfahren T2 - Expertenforum "Faseroptische Sensoren in der praktischen Anwendung" im Rahmen des GESA-Arbeitskreises AK 17: Faseroptische Messverfahren CY - Berlin, Germany DA - 2004-01-27 PY - 2004 AN - OPUS4-4780 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Gloetzl, R. A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Habel, Wolfgang ED - Udd, E. T1 - Geotechnical Pressure Cell Using a Long-Term Reliable High-Precision Fibre Optic Sensor Head T2 - 12th SPIE International Symposium "Smart Structures and Materials 2005 CY - San Diego, CA, USA DA - 2005-03-06 KW - Pressure sensor KW - Fabry-Pérot interferometer KW - Geotechnics KW - Deformation measurement KW - Long-term stability PY - 2005 SN - 0-8194-5739-6 SN - 1605-7422 N1 - Serientitel: SPIE proceedings series – Series title: SPIE proceedings series IS - 5758 SP - 248 EP - 253 PB - SPIE CY - Bellingham AN - OPUS4-11769 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef T1 - Formblattentwurf für die einheitliche Charakterisierung technisch verwertbarer faseroptischer Sensorlösungen T2 - Vortrag auf der Sitzung des GESA-AK 17 "Faseroptische Sensorik". CY - Cologne, Germany DA - 2005-01-20 PY - 2005 AN - OPUS4-11733 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Schukar, Vivien A1 - Tkachenko, Viktoriya A1 - Hofmann, Detlef A1 - Basedau, Frank ED - Xu, Y. L. ED - Zhu, S. ED - Xia, Y. ED - Ni, Y.Q. ED - Law, S.S. ED - Yin, J. H. ED - Su, Z.Q. T1 - Values gained from composite-embedded sensor fibres - trustworthy results or vague estimations; possibilities and limitations of getting reliable measurement results T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure CY - Hong Kong, China DA - 2013-12-09 KW - Composite materials KW - Embedded sensors KW - Monitoring KW - Early damage detection KW - Validation KW - Reliability KW - Maintenance KW - Repair PY - 2013 SN - 978-962-367-768-4 SP - 1 EP - 11(?) AN - OPUS4-29912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hamann, M. A1 - Kubowitz, P. A1 - Hofmann, Detlef ED - Xu, Y. L. ED - Zhu, S. ED - Xia, Y. ED - Ni, Y.Q. ED - Law, S.S. ED - Yin, J. H. ED - Su, Z.Q. T1 - Scale of intelligence in hybrid bridge structures - new aspects of monitoring by using fibre-optic sensors in timber elements N2 - In structural engineering timber is appreciated due to its low weight, its high aesthetic quality and because it is a renewable resource. The market share of timber structures and wood based hybrid structures will clearly increase over the next few years due to greater environmental awareness and a higher demand for sustainability. However, building with timber is marked by characteristics which lead to significant disadvantages in comparison wifh technical materials. For example, in outdoor areas Chemical and structural approaches offen lead to unsatisfactory and expensive Solutions with respect to durability. An idea is to make natural lumber a high-performance material which can be designed to meet the engineers’ demands conceming strength, stiffness, durability, shape, safety etc. These changes can affect the material itself, new technologies or a new approach to monitoring. Especially hybrids made of common timber products and technical textiles or enhanced timber products are high-capacitive and reach high bearing strengths with low material input and good durability. These hybrids are particularly qualified to use the advantages of wood and minimize the disadvantages. They can be used in different ways for load bearing structures, i.e. bridges. New construction types need monitoring to observe the stress and strains for which they were designed, and the structures’ behaviour as well as to guarantee required safety levels. The aim of successful usage of fibre optic measurement technology in timber elements was the development of a technology for measuring the lengthening in timber elements and wood based hybrid elements by using fibre optic sensors. The scientific and technical challenge was to develop an applicationtechnology for optical glass fibres in timber and densified veneer wood. In laboratory tests as well as with the erection of a footbridge and during in-situ tests it could be shown that the structurally integrated fibre optic sensor technology used is suitable for short and long term measurement. The developed embedment technology tums out to be practical and fit for good transfer of strain-values from timber to the modified sensor fibres. T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure CY - Hong Kong, China DA - 09.12.2013 KW - Structural health monitoring KW - Structural engineering KW - Timber KW - Composites KW - Hybrid construction types KW - Fibre optic sensor technology KW - Sensor fibres PY - 2013 SN - 978-962-367-768-4 SP - 1 EP - 10 AN - OPUS4-29913 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Jentsch, H. A1 - Schwartz, A. A1 - Basedau, Frank A1 - Bazrafshan, K. A1 - Döring, H. A1 - Großwig, S. A1 - Hofmann, Detlef A1 - Kowalle, G. A1 - Kusche, Nadine A1 - Lorenz, R. A1 - Pfeiffer, T. A1 - Sadaghiani, M.R.S. A1 - Scholz, E. A1 - Senze, A. A1 - Tkachenko, Viktoriya A1 - Witt, K. J. ED - Xu, Y. L. ED - Zhu, S. ED - Xia, Y. ED - Ni, Y.Q. ED - Law, S.S. ED - Yin, J. H. ED - Su, Z.Q. T1 - Detection of slipping soil areas with embedded tiny vertical sensing rods T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure CY - Hong Kong, China DA - 2013-12-09 KW - Structural health monitoring KW - Soil stability monitoring KW - Optical fibre strain-sensor KW - Geotechnical soil stability KW - Soil deformation modelling PY - 2013 SN - 978-962-367-768-4 SP - 1 EP - 9(?) AN - OPUS4-29915 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Pirskawetz, Stephan A1 - Steinbock, O. A1 - Hille, Falk A1 - Schmidt, S. A1 - Hofmann, Detlef T1 - Erfahrungen aus dem Rückbau der Brücke am Altstädter Bahnhof in der Stadt Brandenburg - Teil 2: Schadensmonitoring bei zerstörenden Versuchen N2 - Im Dezember 2019 wurden bei einer turnusmäßigen Inspektion der B 1-Brücke am Altstädter Bahnhof in Brandenburg an der Havel massive und schnell voranschreitende Schäden festgestellt. Als Ursache für die Risse entlang der Längsträger wurde das Versagen eines signifikanten Anteils der Spanndrähte der konzentrierten Spannglieder vermutet. Die Brücke wurde umgehend für den Verkehr gesperrt und im Mai 2021 gesprengt. Im Vorfeld der Sprengung wurden durch das Bundesministerium für Digitales und Verkehr (BMDV) weiterführende Untersuchungen zum Schadensbild veranlasst, welche vom Landesbetrieb Straßenwesen Brandenburg koordiniert und in den Bauablauf integriert wurden. Das von der Hochschule für Technik und Wirtschaft (HTW) Dresden erstellte Versuchskonzept ist Bestandteil des vorangestellten ersten Teils des Beitrags [1]. Hier im zweiten Teil werden ausgewählte Ergebnisse der umfangreichen versuchsbegleitenden Mess- und Monitoringmaßnahmen beschrieben, welche in Kooperation der HTW Dresden, der Bilfinger Noell GmbH sowie der Bundesanstalt für Materialforschung und -prüfung (BAM) durchgeführt wurden. N2 - A routine inspection of the B1 bridge at the Altstädter Bahnhof in Brandenburg an der Havel in December 2019 revealed massive and rapidly progressing damage. The cause of the cracks along the longitudinal girders was suspected to be the failure of a significant portion of the prestressing wires of the concentrated tendons. The bridge was immediately closed to traffic and demolished in May 2021. Prior to the demolition, the Federal Ministry for Digital and Transport (BMDV) initiated further investigations into the damage pattern, which were coordinated and integrated into the deconstruction process by the Landesbetrieb Straßenwesen Brandenburg. The test concept was developed by the Hochschule für Technik und Wirtschaft Dresden (HTW) and is described in the previous article (Part 1). The article at present (Part 2) describes selected results of the extensive measurement and monitoring measures accompanying the tests. The Tests were carried out in cooperation with the HTW Dresden, Bilfinger Noell GmbH and the Bundesanstalt für Materialforschung und -prüfung (BAM). KW - Spannbetonbrücke KW - Spannstahlbruch KW - Schallemission KW - Fotogrammetrie KW - Faseroptik KW - Stochastische Subspacebasierte Schadensdetektion PY - 2022 DO - https://doi.org/10.1002/best.202200052 SN - 1437-1006 VL - 117 IS - 8 SP - 581 EP - 589 PB - Ernst & Sohn CY - Berlin AN - OPUS4-55513 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Daum, Werner A1 - Gong, Xing A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Schukar, Vivien A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe T1 - New self - diagnostic fiber optical sensor technique for structural health monitoring N2 - Fiber optic sensors have gained increasing importance in recent years and are well established in many areas of industrial applications. In this paper, we introduce a concept of a self-diagnostic fiber optic sensor. The presented sensor is to resolve the problems of embedded fiber optic sensors in complex structures and to enable the validation under operational conditions. For this purpose, different magnetostrictive coated fiber optic sensors were developed and various experiments were performed to verify their mode of Operation and to determine the respective reproducibility. The measuring principle is illustrated by obtained experimental results, which showed a change in wavelength from 1 pm at a magnetic field strength change of 0.25 mT. In addition, the temperature characteristics of the implemented magnetostrictive sensor were analyzed and an experimental factor of 1.5 compared to a reference fiber optic sensor was determined. T2 - 32nd DANUBIA ADRIA SYMPOSIUM on Advances in Experimental Mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Self-diagnostic fiber optical sensor KW - Magnetostrictive metal coating KW - Magnetic field KW - Fiber bragg grating PY - 2016 DO - https://doi.org/10.1016/j.matpr.2016.03.038 SN - 2214-7853 VL - 3 IS - 4 SP - 1009 EP - 1013 AN - OPUS4-37131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandes, K. A1 - Daum, Werner A1 - Hofmann, Detlef A1 - Kubowitz, P. T1 - Lagrange multiplier test for structural damage of bridges N2 - Detecting spreading damage in bridges is a demanding task for engineers today when the ageing infrastracture of industriaiized countries is degradating more and more. To successfully deal with tbis problem, a really advanced method has been elaborated basing on Langrange Multiplier (LM) tests and following the principle of simplicity by Hilbert and extending comments by Helmholtz refering to a combination of measurement and analytical treatment. Finally, an easy mathematical fonnation has been created. T2 - 31st Danubia-Adria Symposium on advances in experimental mechanics CY - Kempten, Germany DA - 24.09.2014 PY - 2014 SN - 978-3-00-046740-0 SP - 213 EP - 214 AN - OPUS4-31725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Daum, Werner T1 - Absolute measuring EFPI-measurement system N2 - The absolute detection of a gap distance of loose and ftxed extrinsic Fabry-Perot interferometer (EFPI) sensors with conventional measurement Systems is not possible. Due to this EFPI-sensors were deemed to be unfit for distance determination in comparision with FBG sensors. With the conventional measurement method a continous measurement of the EFPIsensors was necessary. Otherwise data about the distance change was lost. Additional it is necessary to detect the tumaround points in the interference signal with 100%. This made it worse for the analysis and the use of the sensor. At BAM Federal Institute for Materials Research and Testing a measurement System called “EFPI-Scan” is developed which can measure the absolute gap distance of four connected EFPI-sensors synchronous. Every measurement channel is temperature independetn and long term stable. Test measurements showed a deviation of maximum ±1 gm per hour. Furthermore it is possible to measure with different measurement modes (abolute, relative and a combination of both). Special emphasis should be placed to the absolute measurement accuracy of ± 5 pm at a gap distance determination ftom 40 up to 4000 pm. T2 - 31st Danubia-Adria Symposium on advances in experimental mechanics CY - Kempten, Germany DA - 24.09.2014 PY - 2014 SN - 978-3-00-046740-0 SP - 120 EP - 121 AN - OPUS4-31729 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Schilder, Constanze A1 - Kohlhoff, Harald A1 - Hofmann, Detlef A1 - Habel, Wolfgang T1 - Structure-integrated fibre optic AE sensor for concrete pile testing and monitoring N2 - A highly resolving fibre optic sensor based on the Fabry-Perot technology has been developed for integration into concrete piles with the purpose of static and dynamic pile testing as well as monitoring. The paper presents the design of the sensitive element and first results of large-scale model pile tests. T2 - Photonics 2010 - 10th International conference on fiber optics & photonics CY - Guwahati, India DA - 2010-12-11 KW - Concrete-embedded fibre optic sensors KW - Fabry Perot sensor KW - Strain measurement KW - Dynamic pile testing KW - Pile integrity KW - Cast-in-place bored piles PY - 2010 SN - 978-81-309-1719-1 IS - 256_SEN_Schilder_C_1_full SP - 1 EP - 4 AN - OPUS4-23272 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Westphal, Anja A1 - Sahre, Mario A1 - Gong, Xin A1 - Bartholmai, Matthias A1 - Beck, Uwe T1 - Magnetic field detection with an advanced FBG-based sensor device N2 - A high-performance fiber Bragg grating-based (FBG) sensor device has been developed for the detection of small magnetic fields. Based on a smart multilayer jacket around the fibre over the physical length of the FBG, magnetic fields generated by rotating machine parts, power generators or power cable can be easily detected, analysed and evaluated. Consequently, this innovative, on-line and non-contact inspection method results in an increase in quality and reliability of high-performing machine parts, devices and cables. The basic physical principle is based on a magnetostrictive multilayer system that strains the high-resolution FBG element in presence of magnetic fields. Subsequently, a fixed relationship between induced magnetic field and wavelength change of the FBG element describes the characteristic sensitivity curve. Intensive tests regarding characterisation of this magnetic field FBG sensor have been carried out and its performance has been evaluated. T2 - 30th Eurosensors Conference, EUROSENSORS 2016 CY - Budapest, Hungary DA - 04.09.2016 KW - Fiber Bragg grating KW - Magnetostriction KW - Strain KW - Magnetic field PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-376703 DO - https://doi.org/10.1016/j.proeng.2016.11.445 SN - 1877-7058 VL - 168 SP - 1270 EP - 1274 PB - Elsevier Ltd. AN - OPUS4-37670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe A1 - Gong, Xing A1 - Bartholmai, Matthias ED - Aulova, Alexandra ED - Rogelj Ritonja, A. ED - Emri, I. T1 - A contribution to intelligent automatic validation of structure-integrated fibre optic strain sensors N2 - Sensors integrated into devices and structures provide essential data to control, optimize or manage machines and structural components. In the last years, processes, applications and machine parts became more and more intelligent. Consequently, the need for sensor validation increased significantly in order to rely on sensor data and measurement results. Structure-integrated fibre optic strain sensors, such as fiber Bragg gratings (FBG), are of special interest in the composite manufacturing industry. This type of sensor makes it possible to gain information and to collect measurement data about entire production processes and whole life-time cycles of composite-made machine parts and structures. However, validation concepts and approaches for this type of sensors are barely reported in literature. Furthermore, all the reported activities have the drawback that the sensor diagnosis strategy is implemented as limited mathematical models and/or complex time-consuming spectral analysis tools which are applied in data post-processing loops. However, to automate sensor validation and to apply real-time and in-field sensor fault detection, it is necessary to acquire measurement data and information about the measurement reliability at the same time. T2 - 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Fiber bragg grating KW - Magnetic field KW - Magnetostrictive metal coating KW - Self-diagnostic fiber optical sensor PY - 2016 SN - 978-961-94081-0-0 SP - 180 EP - 181 CY - Ljubljana AN - OPUS4-37645 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Kupferschmidt, C. T1 - Zuverlässigkeit von optischen Fasern zur Dehnungsmessung in Offshore-Anwendungen T2 - 4. Zukunftskonferenz: Wind & Maritim CY - Rostock, Germany DA - 2015-05-06 PY - 2015 AN - OPUS4-33750 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Basedau, Frank A1 - Hofmann, Detlef A1 - Krebber, Katerina A1 - Jentsch, H. A1 - Senze, A. ED - Ilki, A. ED - Motavalli, M. ED - Inci, P. ED - Köhli, M. T1 - Online-detection of slipping soil areas by embedded fiber-optic sensing rods N2 - Movements in geological areas are often caused by shear zones deep in the underground or by hardly observable slipping zones. Detection of movements reaching critical values is of crucial importance to avoid losses and harms. Optical sensor fibers with gauge lengths of several meters or even distributed fiber-optic sensors with gauge lengths of hundreds of meters allow detecting deformation of such zones with quite good resolution. The paper presents a new technology of detecting deformations and movements in soil or rock massifs. The core part of the sensing system is a tiny pultruded rod with an outer diameter of 3 mm to 6 mm. It contains two fiber-optic sensor systems. One sensor system is used for permanent online measurement and provides integral strain information along the whole length of the rod; in case of critical deformations, it provides a warning signal. The second sensing system uses fiber-optic Bragg grating (FBG) strain sensors located close to the expected shear zone. This measurement system will be activated after the warning signal has been initiated by the integral strain measurement system. The FBG strain sensor system records then resulting deformations in detail. The sensing rod containing both sensor systems can be installed in a borehole to detect beginning soil movements automatically. The electronic equipment is powered by a solar panel; the amount of deformation in soil or rock formations can be estimated from the strain change measured in the sensor fibers. The effectiveness of this warning system will be shown using the example of a critically sliding slope in an open brown coal pit in Germany. T2 - SMAR 2015 - 3rd Conference on smart monitoring, assessment and rehabilitation of civil structures CY - Antalya, Turkey DA - 07.09.2015 KW - SHM KW - Standardization KW - Reliability KW - Fibre-optic sensor KW - Embedded sensor KW - Monitoring KW - Maintenance PY - 2015 SN - 978-3-905594-65-2 SP - Paper 222, 1 EP - 8 AN - OPUS4-34544 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandes, K. A1 - Daum, Werner A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Kubowitz, P. T1 - Innovative structural damage detection of bridges by least squares adjustment with constraints T2 - 32nd Danubia-Adria Symposium on advances in experimental mechanics CY - Starý Smokovec, Slovakia DA - 2015-09-22 PY - 2015 SN - 978-80-554-1094-4 SP - 18 EP - 19 CY - Zilina AN - OPUS4-34486 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Hussels, Maria-Teresa T1 - Bauteil- und Strukturmonitoring mit faseroptischer Sensorik, Teil 1: Diskrete (punktuelle) Messwerterfassung T2 - Sommerschule des DFG-Forscherverbunds FOR 2021: Wirkprinzipien nanoskaliger Matrixadditive für den Faserverbundleichtbau CY - Berlin, Germany DA - 2015-08-25 PY - 2015 AN - OPUS4-34074 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandes, K. A1 - Kubowitz, P. A1 - Daum, Werner A1 - Hofmann, Detlef A1 - Basedau, Frank T1 - Lagrange Multiplikator-Test zur Detektierung von zunehmender Strukturschädigung N2 - Mit einem auf Lagrange-Multipiikator-Tests basierenden Monitoring von Brücken ist es gelungen, in Belastungsversuchen an einer Holzbrücke (7,25 m Spannweite), an der relativ kleine Schädigungen künstlich herbeigeführt worden waren, die Zuverlässigkeit dieser Art des Monitorings zu bestätigen. Ausgangspunkte waren Messung von Durchbiegungen sowie Krümmungen und die Zusammenführung der jeweiligen Regression mit Nebenbedingungen, die den mechanischen Bedingungen gehorchen, unter Einschluss von Lagrange-Multiplikatoren, die sich als brauchbare Testparameter erwiesen. T2 - 8. Symposium Experimentelle Untersuchungen von Baukonstruktionen CY - Dresden, Germany DA - 24.09.2015 KW - Schadensfrüherkennung KW - Strukturschädigung KW - Monitoring PY - 2015 SN - 1613-6934 N1 - Serientitel: Schriftenreihe Konstruktiver Ingenieurbau Dresden – Series title: Schriftenreihe Konstruktiver Ingenieurbau Dresden IS - 40 SP - 147 EP - 157 CY - Dresden AN - OPUS4-34793 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Daum, Werner T1 - Absolut messendes EFPI-Messsystem N2 - In diesem Paper wird ein absolut messendes faseroptisches Messsystem zur Bestimmung des Gap-Abstandes von niedrig reflektierenden losen und festen extrinsischer Fabry-Pérot Interferometer (EFPI) vorgestellt. Die häufigste Methode zur Bestimmung von Dehnungen oder Bewegungen durch EFPI-Sensoren ist eine kontinuierliche relative Ermittlung einer Veränderung mit einer nachträglichen Auswertung. Unterbrechungen in der Datenerfassung oder Fehler bei der Interferenzstreifen-Auswertung führen zu einer nicht abschätzbaren Messunsicherheit. Damit war es bis dato nicht möglich, eine absolute Veränderung von eingesetzten EFPI-Sensoren zu bestimmen. Mit dem an der BAM entwickelten Verfahren, ist dies jetzt möglich, die absolute Veränderung zu bestimmen. Dieses System namens 'EFPI-Scan' wird in dem Papier dargestellt werden. T2 - Sensoren und Messsysteme 2014 - 17. ITG/GMA-Fachtagung CY - Nürnberg, Germany DA - 03.06.2014 PY - 2014 SN - 978-3-8007-3622-5 SN - 0932-6022 N1 - Serientitel: ITG-Fachbericht – Series title: ITG-Fachbericht VL - 250 SP - P16.2, 1 EP - 3 PB - VDE Verlag GmbH AN - OPUS4-32644 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Kupferschmidt, C. T1 - Zuverlässigkeit von optischen Fasern zur Dehnungsmessung in Offshore-Anwendungen T2 - 4. Zukunftskonferenz: Wind & Maritim CY - Rostock, Germany DA - 2015-05-06 PY - 2015 AN - OPUS4-33742 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Kubowitz, P. A1 - Habel, Wolfgang A1 - Basedau, Frank A1 - Brandes, Klaus T1 - Embedding of Fibre-Optic Sensors in High-Performance Timber Structures T2 - 31th Danubia-Adria Symposium CY - Kempten, Germany DA - 2015-09-24 PY - 2015 AN - OPUS4-33743 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Hofmann, Detlef A1 - Döring, H. A1 - Jentsch, H. A1 - Senze, A. A1 - Kowalle, G. ED - Shi, B. T1 - Detection of a slipping soil area in an open coal pit by embedded fibre-optic sensing rods N2 - Movements in geological areas are mostly concentrated on faults or slipping zones. Detection of movements reaching critical values is of crucial importance to avoid losses and harms. The paper presents a new technology of detecting deformations and movements in soil or rock massifs. The core part of the sensing system is a tiny rod with embedded optical sensor fibres. This deformation measurement system was developed and the sensing rod can be installed in a borehole and enables the detection of beginning soil movements. The amount of deformation in soil or rock formations can then be estimated. The sensing rod has an outer diameter of 3 mm to 6 mm and contains several optical fibres. One fibre is used as online measurement system and provides integral strain information along the whole length of the rod. In case of a safety-relevant deformation (warning signal), the second sensing system based on fibre Bragg grating sensors positioned close to the expected shear zone will be activated and records then resulting deformations in detail. T2 - OSMG-2014 - 5th International forum on opto-electronic sensor-based monitoring in geo-engineering CY - Nanjing, China DA - 12.10.2014 KW - Fibre-optic strain sensor KW - Structural health monitoring KW - Soil stability monitoring KW - Early warning PY - 2014 SP - 1 EP - 7 AN - OPUS4-32664 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Krebber, Katerina ED - Lutz, B. ED - Möller, G. ED - Rücker, Werner ED - Schiefelbein, N. T1 - Herausforderungen bei der Nutzung faseroptischer Sensoren für spezielle geotechnische Fragestellungen N2 - Geotechnische Tätigkeitsfelder und Forschungsaufgaben haben sich immer an den modernen Herausforderungen orientiert und umfassen z. B. die Beschreibung und Quantifizierung der Interaktion zwischen Baugrund und Bauwerk, die Untersuchung des Untergrunds besonders hinsichtlich der technischen und sozialen Infrastrukturen und die Beeinflussung der Umwelt. Fragen der zivilen Sicherheit stellen steigende Anforderungen an die Tragfähigkeit und Dauerhaftigkeit von Bauwerken. Zur Lösung dieser Aufgaben entstehen vielfältige interessante Methoden und Verfahren zur Strukturbewertung, die neben der Erfassung des allgemeinen Zustands auch neue Erkenntnisse zum Bauwerksverhalten im Hinblick auf moderne Bautechnologien und auf die Lebensdauer von Bauwerken liefern. Die systematische, zuverlässige und langzeitstabile Erfassung von geotechnischen Messgrößen und Parametern bei der Strukturbewertung sowie die Beobachtung und Bewertung der geologischen Gegebenheiten mit technischen Hilfsmitteln ist dafür unerlässlich und lässt sich mit den Begriffen Zustandsanalyse und Bauwerksmonitoring zusammenfassen. Das Ziel dabei ist, mögliche Schädigungsmechanismen frühzeitig zu erkennen, um rechtzeitig Gegenmaßnahmen ergreifen zu können. T2 - Messen im Bauwesen 2014 - Neue Messtechniken und Anwendungsfälle CY - Berlin, Germany DA - 04.03.2014 KW - Faseroptische Sensorik KW - Optische Messverfahren KW - Fabry-Perot-Interferometer KW - Faser-Bragg-Gitter KW - Applikation KW - Anwendungen KW - Geomatten KW - Raman KW - Brillouin PY - 2014 SN - 978-3-9815944-7-8 SP - 7 EP - 26 AN - OPUS4-33812 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Vivien A1 - Gong, Xin A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe ED - Berghmans, F. ED - Mignani, A. G. T1 - Modelling and simulation of a fibre Bragg grating strain sensor based on a magnetostrictive actuator principle N2 - A new concept for the self-diagnosis of embedded fiber Bragg grating (FBG) strain sensors was developed, simulated and experimentally tested. This concept is based on a magnetostrictive metallic layer directly coated on the fibre cladding over the grating segment of the FBG sensor, so that an on-demand external magnetic field in a millitesla scale can produce a controllable artificial strain as an indication signal for the remote optical interrogator. The relationship between the pre-defined magnetic field and its induced Bragg wavelength shift characterizes this validation concept. Any deviation of the local bonding state of the interfaces from the initial or/and any change of shear strain transferring mechanism from composite matrix to the optical fibre core will result in alterations in this sensitive relationship, and thus triggers an immediate alert for a further inspection. The finite element method is used to simulate the strain of this configuration as result of different values of the magnetic field in order to optimize the geometrical sensor parameters. The simulations are verified by experiments results. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only. T2 - Optical Sensing and Detection IV CY - Brüssel, Belgium DA - 03.04.2016 KW - Fiber Bragg gratings KW - Actuators KW - Modeling and simulation KW - Finite element methods PY - 2016 SN - 9781510601444 DO - https://doi.org/10.1117/12.2224728 SN - 0277-786X SN - 1996-756X VL - 9899 SP - 9899-39 PB - SPIE Digital Library AN - OPUS4-38634 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Brandes, K. A1 - Daum, Werner A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Kubowitz, P. T1 - Innovative structural damage detection of bridges by least squares adjustment with constraints N2 - Long-term monitoring of bridges requires the early detection of spreading damage because very often the damage is not really visible. For many decades engineers and scientists relayed on dynamic methods especially modal ones. However, after fundamental tests by the U.S. FHWA in 1993, it became evident that more successful methods should be developed, but no innovation really happened. A substantial innovative detection method started four years ago from Lagrange Multiplier Testing which eventually resulted in experimental verification based on measurement of deflection and curvature of the bridge beam and together the methodological combination of both. T2 - 32nd DANUBIA ADRIA SYMPOSIUM on Advances in Experimental Mechanics CY - Starý Smokovec – High Tatras, Slovakia DA - 22.09.2015 KW - Damage detection of bridges KW - Monitoring KW - Lagrange multiplier test PY - 2016 DO - https://doi.org/10.1016/j.matpr.2016.03.025 SN - 2214-7853 VL - 3 IS - 4 SP - 942 EP - 946 PB - Elsevier AN - OPUS4-36667 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mitzkus, Anja A1 - Sahre, Mario A1 - Reinstädt, Philipp A1 - Griepentrog, Michael A1 - Beck, Uwe A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Basedau, Frank A1 - Hofmann, Detlef A1 - Gong, Xin A1 - Schukar, Vivien T1 - Altbekannter Watts-Elektrolyt, junge Hightech-Anwendung, Nickel- und Nickel-Eisen-Schichten als magnetostriktive Aktorschicht auf faseroptischen Sensoren N2 - Durch faseroptische Sensoren können Bauteile im Einsatz kontinuierlich überwacht und frühzeitig Informationen über Materialveränderungen gewonnen werden. Mittels einer magnetostriktiven Aktorschicht, welche den Sensor umhüllt, kann nun auch die korrekte Sensorfunktion jederzeit kontrolliert werden. Als Aktorschicht eignet sich galvanisch abgeschiedenes reines Nickel oder Nickel-Eisen in der Zusammensetzung 50:50. Um diese haftfest mit dem Sensor zu verbinden wurde ein ECD/PVD-Kombinationsschichtsystem entwickelt. Die mechanischen Eigenschaften der ECD-Schicht können sowohl mit einer auf die Fasergeometrie angepassten instrumentierten Eindringprüfung als auch einem 2-Punkt-Biegeversuch bestimmt werden. KW - Faseroptik-Sensoren KW - ECD-Aktorschicht KW - PVD-Haftfestigkeit KW - Nickel-/Nickel-Eisen- Magnetostriktion PY - 2016 SN - 2195-5891 SN - 2195-5905 VL - 12 SP - 1 EP - 4 AN - OPUS4-39129 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Beck, Uwe A1 - Mitzkus, Anja A1 - Sahre, Mario A1 - Weise, Matthias A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Basedau, Frank A1 - Hofmann, Detlef A1 - Schukar, Vivien T1 - Faser-basierter magneto-optischer Schicht-Sensor zum Monitoring von Bauteilen N2 - In Glasfasern eingeschriebene Bragg-Gitter (FBG: fibre-based Bragg gratings) sind über die Verschiebung der Bragg-Wellenlänge in der Lage, Stauchungen und Dehnungen von Glasfasern hochgenau zu erfassen. In Kompositwerkstoffe eingebettete faseroptische Sensoren können Bauteile bezüglich ihrer mechanischen Integrität überwachen und früh-zeitig Informationen über Materialveränderungen gewinnen. Um die Zuverlässigkeit eines solchen Sensors zu gewährleisten, ist es wichtig, die korrekte Funktion des Sensors im Verbund mit der Werkstoff-Matrix on-line und in-situ sicherzu-stellen. Im Rahmen des DFG-Projekts FAMOS² (FAser-basierter Magneto-Optischer SchichtSensor) wurde ein selbstdiagnosefähiger Schichtsensor entwickelt, der mit Hilfe von magnetostriktiven Aktorschichten aus Nickel bzw. Eisen-Nickel validiert werden kann. Der FAMOS²-Schichtsensor wird durch ein PVD (physical vapour deposition)/ECD (electro-chemical deposition) Hybridschichtsystem realisiert, das auf dem Fasermantel im Bereich des FBG haftfest, homogen und langzeitfunktional abzuscheiden ist. Dabei wird in einem ersten Schritt ein etwa 100 Nanometer dünnes PVD-Schichtsystem aus Chrom und Kupfer als Haftvermittler auf der Glasfaser bzw. als leitfähige Startschicht für den nachfolgenden ECD-Prozess abgeschieden. Um eine rotationssymmetrische Schich-tabscheidung zu gewährleisten, erfolgt während der PVD-Beschichtung eine Rotation der Glasfasern. In einem zweiten Schritt wird dann unter Verwendung eines klassischen Watts-Elektrolyten in einer speziell entwickelten ebenfalls rotationssymmetrisch aufgebau-ten ECD-Durchströmungszelle dann die etwa 30 Mikrometer dicke, magnetostriktive Ak-torschicht auf dem PVD-Schichtsystem abgeschieden, im Vergleich sowohl reine Nickel-Schichten als auch Nickel-Eisen-Schichten. Ein äußeres Magnetfeld dehnt die magnetostriktive Aktorschicht und damit auch die Faser reversibel. Diese Dehnung führt zu einer Verschiebung der Bragg-Wellenlänge, welche direkt mit der Stärke eines zu messenden oder zu Validierungszwecken vorgegebenen Magnetfeldes korreliert. Die Anpassung der Beschichtungsverfahren an die Fasergeome-trie und die mechanischen Eigenschaften der Hybridschichten werden hinsichtlich der me-chanischen Integrität des faseroptischen Sensors diskutiert und der Nachweis der Selbst-diagnosefähigkeit erbracht. T2 - 13. ThGOT Thementage Grenz- und Oberflächentechnik und 11. Thüringer Biomaterial-Kolloquium CY - Zeulenroda, Germany DA - 13.03.2018 KW - Magneto-optischer Sensor KW - Faser-Bragg Gitter KW - Magnetostriktive Beschichtung KW - Selbstkalibrierung KW - Bauteilmonitoring PY - 2018 SN - 978-3-00-058187-8 SP - 1 EP - 5 CY - Jena AN - OPUS4-44599 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Schukar, Vivien A1 - Hofmann, Detlef T1 - Requirements to establish fibre-optic sensors for monitoring of structures N2 - Fibre-optic sensors need to be more established in the sensor market. Their advantages have unquestionably been verified by numerous demonstrations. However, there are some open questions leading now and then to restraints in the user's community. The paper dicusses examples where fibre-optic sensors provide outstanding knowledge about the structure's behaviour, but application is often challenging. Requirements are listed and open questions to be solved are discussed. Short outlook to standards useful for better design, characterization and application is given. Standards are the basis for establiching SHM systems, especially for safety-critical structural diagnostics. T2 - EWSHM 2014 - 7th European workshop on structural health monitoring CY - Nantes, France DA - 08.07.2014 KW - Monitoring KW - Fibre-optic sensor KW - Reliability KW - Application PY - 2014 SP - 2330 EP - 2337 AN - OPUS4-32662 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Daum, Werner A1 - Gong, Xin A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Schukar, Vivien A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe T1 - New self diagnostic fiber optical sensor technique for structural health monitoring N2 - Fiber optic sensors have gained increasing importance in recent years and are well established in many areas of industrial applications. In this paper, we introduce a concept of a self-diagnostic fiber optic sensor. The presented sensor is to resolve the problems of embedded fiber optic sensors in complex structures and to enable the validation under operational conditions. For this purpose, different magnetostrictive coated fiber optic sensors were developed and various experiments were performed to verify their mode of operation and to determine the respective reproducibility. The measuring principle is illustrated by obtained experimental results, which showed a change in wavelength from 1 pm at a magnetic field strength change of 0.25 mT. In addition, the temperature characteristics of the implemented magnetostrictive sensor were analyzed and an experimental factor of 1.5 compared to a reference fiber optic sensor was determined. T2 - 32nd Danubia-Adria Symposium on advances in experimental mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 PY - 2015 SN - 978-80-554-1094-4 SP - 1 EP - 2 CY - Zilina AN - OPUS4-35173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Heidenreich, F. A1 - Herten, M. T1 - Verwendung faseroptischer Messtechnik im Zuge wiederholter Eignungsprüfungen an Verpressankern N2 - Im Rahmen des Ausbaus des Dortmund-Ems-Kanals wurden an der Schleuse Gleesen Forschungsanker installiert, die Rückschlüsse auf das Tragverhalten in Folge des chemischen Angriffs kalklösender Kohlensäure geben sollen. Die Forschungsanker werden seit der Erstellung im Jahr 2017 mit verteilter faseroptischer Sensorik während der jährlichen Eignungsprüfungen untersucht. Die Ergebnisse der Jahre 2017 bis 2019 werden im Folgenden dargestellt. T2 - Messen in der Geotechnik 2020 CY - Braunschweig, Germany DA - 20.02.2020 KW - Faseroptische Sensorik KW - Rayleigh Rückstreuung KW - Verpressanker KW - Chemischer Angriff KW - Rissbildung PY - 2020 SN - 978-3-948141-02-8 DO - https://doi.org/10.24355/dbbs.084-201912181435-0 IS - 110 SP - 297 EP - 323 AN - OPUS4-51687 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef T1 - Strukturüberwachung mit lokaler und verteilter faseroptischer Sensorik N2 - Der Vortrag gibt einen Überblick über die Einsatzmöglichkeiten faseroptischer Sensorik (FOS) als ZfP-Verfahren. Dabei werden an Beispielen lokale und verteilte faseroptische Verfahren zur Dehnungs-, Temperatur- und Risserfassung sowie zur akustischen Messung vorgestellt. Weiterhin werden Möglichkeiten zur Selbstdiagnose von FOS aufgezeigt. T2 - InnoTesting2020 "Innovative Ideen - neue Testmethoden" CY - Wildau, Germany DA - 27.02.2020 KW - Faseroptische Sensorik KW - Strukturüberwachung KW - Lichtwellenleiter KW - Zerstörungsfreie Prüfung KW - Selbstdiagnose PY - 2020 AN - OPUS4-51688 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hüsken, Götz A1 - Shamsuddoha, Md A1 - Pirskawetz, Stephan A1 - Hofmann, Detlef A1 - Baeßler, Matthias A1 - Kühne, Hans-Carsten T1 - Potential of a Repair System for Grouted Connections in Offshore Structures: Development and Experimental Verification N2 - Grouted connections are intensively used in offshore rigs, platforms as well as jacket and monopile offshore wind turbine structures. Being located in remote offshore conditions, these connections can experience considerable adverse loading during their lifetimes. Degradation was reported inside similar connections, which were installed in the last three decades. Grouting in the offshore sites may often be proven difficult, which eventually leads to reduced load-bearing capacity of connections in the long run. Thus, repair and rehabilitation of such connections should be planned ahead to minimize operational delays and costs. In this study, scaled grouted connections were manufactured using a novel mould, whose integrity were monitored using digital image correlation (DIC). The connections were loaded under static load to visualize the main failure pattern using distributed fibre optic sensors and acoustic emission (AE) analysis. Grouted connections were then repaired using a cementitious injectable grout. The effectiveness of the grout injection was monitored using dye penetration technique. Finally, specimens are reloaded to identify the potential of such repair for grouted connections. KW - Offshore KW - Grouted connection KW - Fibre optic sensors KW - Acoustic emission analysis KW - Cracks KW - Repair KW - Rehabilitation KW - Static loading PY - 2021 DO - https://doi.org/10.1016/j.marstruc.2021.102934 VL - 77 SP - 102934 PB - Elsevier Ltd. AN - OPUS4-52059 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hüsken, Götz A1 - Pirskawetz, Stephan A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Gründer, Klaus-Peter A1 - Kadoke, Daniel T1 - The load-bearing behaviour of a reinforced concrete beam investigated by optical measuring techniques N2 - Bending beams and slabs are typical examples for structural elements used for reinforced concrete structures such as bridge girders, T-beams and bridge decks. Their strength related failure modes at maximum loading can be divided into bending and shear failure. The failure of beams loaded in bending can occur with or without indication. Therefore, conventional design concepts aim on failure modes with sufficient indication (e.g. large deflections or cracks), as it occurs in the case of secondary flexural compression failure. These indicating factors can also be used for Structural Health Monitoring (SHM) of civil infrastructure systems (e.g. bridges) to identify structural changes. In this context, non-destructive testing (NDT) methods offer different techniques for measuring deflections or crack formation and opening. However, profound knowledge on the determining failure modes of bending beams and their detection by NDT methods is required for the reliable application of SHM. Different NDT methods have been used in this study for analysing the load-bearing behaviour of a reinforced concrete beam in bending. The different measuring techniques are briefly described and their applicability is discussed by means of experimental results. For this purpose, the load-bearing behaviour of a reinforced concrete beam having a span of 2.75 m was investigated in a four-point bending flexural test at laboratory scale. The focus is on the characterization of determining failure modes by optical NDT and the comparison with classical measuring techniques (e.g. deformation measurements by displacement transducers). The bending beam was equipped with two single-mode (SM) sensor fibres. One fibre served as Distributed Optical Fibre Sensor (DOFS), whereas the other fibre contained Fibre Bragg Grating (FBG) sensors. In addition, optical deformation measurements using Digital Image Correlation (DIC) and Stereophotogrammetry (SP) were conducted. KW - Concrete beam KW - Bending KW - Digital image correlation KW - Stereophotogrammetry KW - Distributed fibre optic sensor KW - Fibre bragg grating PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-524762 DO - https://doi.org/10.1617/s11527-021-01699-6 VL - 54 IS - 3 SP - Article 102 PB - Springer AN - OPUS4-52476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Daum, Werner A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Brandes, K. A1 - Kubowitz, P. ED - Curbach, M. ED - Opitz, H. ED - Scheerer, S. ED - Hampel, T. T1 - Erweiterte Strukturabbildung von Brücken mit adaptiven mathematischen Modellen zur Lösung aktueller noch ungelöster Probleme N2 - Health monitoring von größeren Strukturen erfordert die Betrachtung der gesamten Struktur, indem sowohl jener Bereich, der experimentell behandelt wird, als auch derjenige, der einer analytischen mechanischen Untersuchung unterzogen wird, in einem Gesamtzusammenhang erfasst wird. Die umfassende Behandlung des Problems gelingt dann in einer Gesamtmatrix, die im Beitrag vorgestellt wird. Auf eine Erweiterung der Methode zur Detektierung anwachsender Schädigungen wird hingewiesen. KW - Structural Health Monitoring KW - Schadensdetektion KW - Adaptives mathematisches Modell PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:bsz:14-qucosa-201229 SN - 1613-6934 VL - Konstruktiver Ingenieurbau Dresden IS - 43 SP - 183 EP - 188 PB - Institut für Massivbau, TU Dresden CY - Dresden AN - OPUS4-43371 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef T1 - Neue Aspekte zum Einsatz faseroptischer Sensoren in Ingenieurbauwerken N2 - Die Anwendung faseroptischer Sensoren, insbesondere von Faser-Bragg-Sensoren, an Holztragwerken wird vorgestellt und an Beispielen Möglichkeiten des Einsatzes verteilter faseroptischer Messverfahren gezeigt. T2 - Angewandte Forschung im Bauwesen - Anwenderkonferenz CY - Berlin, Germany DA - 22.09.2017 KW - Fasersensorik KW - Faser-Bragg-Gitter KW - Diskrete Messtechnik KW - Ortsaufgelöste Messung KW - Ortsverteilte Messtechnik PY - 2017 AN - OPUS4-42587 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Pötschke, Samuel A1 - Breithaupt, Mathias A1 - Schukar, Marcus T1 - Funktionsprinzip faseroptischer Sensoren N2 - Das Poster präsentiert die Grundlagen zur Funktionsweise optischer Fasern bzw. faseroptischer Sensoren, die im Rahmen eines Feldversuchs zum Einsatz kommen. T2 - Tag der offenen Tür auf dem Testgelände der BAM (BAM TTS) CY - Horstwalde, Germany DA - 29.09.2018 KW - Faseroptische Sensorik KW - Verteilte Messverfahren KW - Quasi-verteilte Messverfahren PY - 2018 AN - OPUS4-46333 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Pötschke, Samuel A1 - Breithaupt, Mathias A1 - Schukar, Marcus T1 - Die durchleuchtete Brücke N2 - Das Poster gibt einen Überblick zum Themenfeldprojekt BLEIB und präsentiert ausgewählte Ergebnisse faseroptischer Messungen bei verschiedenen Belastungsszenarien an der Versuchsbrücke. T2 - Tag der offenen Tür auf dem Testgelände der BAM (BAM TTS) CY - Horstwalde, Germany DA - 29.09.2018 KW - Bauwerksüberwachung KW - Faseroptische Sensorik KW - Dehnungsmessung KW - Temperaturmessung KW - Verteilte Messverfahren PY - 2018 AN - OPUS4-46334 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Mitzkus, Anja A1 - Gong, Xin A1 - Sahre, Mario A1 - Bartholmai, Matthias A1 - Beck, Uwe ED - Emri, Igor T1 - A contribution to intelligent automatic validation of structure-integrated fibre optic strain sensors N2 - An auto-validation tool for the reliability quantification of materials integrated fiber Bragg grating (FBG) strain sensors have been developed and tested. The FBG strain sensor was jacketed with a magnetostrictive layer based on iron-nickel which, when excited by a specific magnetic field, adds an artificial strain to the sensor. The fixed relationship between magnetic induction and wavelength shift of the FBG strain sensor characterizes the bond strength and adhesion between the sensor and the surrounding structure. Due to an easily applicable magnetic field, it is possible to validate the sensor performance in a non-contact, fast way without disturbing the data-acquisition process. T2 - 33nd Danubia Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Fiber Bragg grating KW - Self-diagnosis KW - Magnetostriction KW - Strain KW - Auto-validation PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S2214785317308489 DO - https://doi.org/10.1016/j.matpr.2017.06.073 SN - 2214-7853 VL - 4 IS - 5, Part 1 SP - 5935 EP - 5939 PB - Elsevier Ltd. AN - OPUS4-41583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilder, Constanze A1 - Kohlhoff, Harald A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Habel, Wolfgang A1 - Baeßler, Matthias A1 - Niederleithinger, Ernst A1 - Georgi, Steven A1 - Herten, M. ED - Jaroszewicz, L.R. T1 - Static and dynamic pile testing of reinforced concrete piles with structure integrated fibre optic strain sensors N2 - Static and dynamic pile tests are carried out to determine the load bearing capacity and the quality of reinforced concrete piles. As part of a round robin test to evaluate dynamic load tests, structure integrated fibre optic strain sensors were used to receive more detailed information about the strains along the pile length compared to conventional measurements at the pile head. This paper shows the instrumentation of the pile with extrinsic Fabry-Perot interferometers sensors and fibre Bragg gratings sensors together with the results of the conducted static load test as well as the dynamic load Tests and pile integrity tests. T2 - EWOFS 2013 - 5th European workshop on optical fibre sensors CY - Kraków, Poland DA - 19.05.2013 KW - Static load test KW - Dynamic load test KW - Pile integrity test KW - Extrinsic Fabry-Perot interferometer KW - Fibre Bragg grating KW - Structure integrated sensor KW - Fibre optic strain sensor PY - 2013 SN - 978-0-81949-634-8 DO - https://doi.org/10.1117/12.2026813 SN - 0277-786X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 8794 IS - Paper 8794 - 181 SP - 700 EP - 703 AN - OPUS4-28854 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Baensch, Franziska A1 - Hofmann, Detlef A1 - Johann, Sergej A1 - Tiebe, Carlo A1 - Basedau, Frank A1 - Sturm, Patrick A1 - Lay, Vera A1 - Niederleithinger, Ernst T1 - Multi-sensor conception for safe sealing structures in underground repositories N2 - The project "SealWasteSafe" of the Bundesanstalt für Materialforschung und -prüfung (BAM, Berlin) deals with sealing structures applied for underground disposal of nuclear waste from two perspectives: (1) material improvement for application in sealing constructions and (2) feasibility study regarding multi-sensor approaches to ensure quality assurance and long-term monitoring. One specimen of 150 l made of alkali-activated material, which was found innovative and suitable for sealing constructions based on preliminary laboratory studies, and, for comparison purpose, another one made of salt concrete, are manufactured with an integrated multi-sensory setup for quality assurance and long-term-monitoring. The specimens were left in their cast form and additionally thermally insulated to simulate the situation in the repository. The multi-sensory concept comprises RFID technology embedded in the specimens suppling material temperature and moisture measurements, integrated fibre optic sensing allowing strain measurement and acoustic emission testing for monitoring possible crack formation. Overall, the suitability and the functionality of the sensors embedded into and attached to strongly alkaline (pH > 13 for the AAM) and salt corrosive (NaCl) environment was proven for the first 672 h. First temperature measurement based on RFID succeeded after 626 h for the alkali-activated material and after 192 h for the conventional salt concrete. Strain measurement based on distributed fibre optic sensing turned out the alkali-activated material with > 1 mm m-1 undergoing approximately twice the compression strain as the salt concrete with strains < 0.5 mm m-1. In contrast, the acoustic emission first and single hits representing crack formation in numbers, was found for alkali-activated material half of that detected at the salt concrete. T2 - SMIRT 26 CY - Berlin/Potsdam, Germany DA - 10.07.2022 KW - SealWasteSafe KW - Monitoring KW - Acoustic emission KW - Fibre optic sensing KW - RFID technology KW - alkali-activated material PY - 2022 SP - 1 EP - 10 AN - OPUS4-55371 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Mielentz, Frank A1 - Prabhakara, Prathik A1 - Baensch, Franziska A1 - Johann, Sergej A1 - Hofmann, Detlef A1 - Sturm, Patrick A1 - Stamm, Michael A1 - Niederleithinger, Ernst T1 - Multi-sensory monitoring and ultrasound for quality assurance at underground sealing structures N2 - Within the safety concepts of underground disposal sites of nuclear waste, engineered barriers play an important role. As these sealing structures have high demands concerning integrity, we aim at advancing the available construction materials, monitoring, and inspection techniques within the project SealWasteSafe. A specifically developed alkali-activated material is compared to classical salt concrete. A comprehensive multi-sensory monitoring scheme is used at 150-340 l specimens to monitor setting and hardening of both materials. All sensors are demonstrated to resist the highly alkaline environments. Besides cabled and wireless temperature and humidity of the materials, strain variations using fibre optic sensors and acoustic emissions are recorded over periods of at least 28 days, partly for more than eight months. After hardening of the specimens, further nondestructive evaluations using ultrasonic echo and thermographic measurements are conducted. Preliminary results proof the suitability of the tested sensors and clearly highlight differences between the tested materials. Particularly, the newly developed alkali-activated material shows lower acoustic emission activity indicating less cracking activity. Additionally, unique ultrasonic methods will enable better images of potential internal objects and cracks at in-situ sealing structures. A largescale ultrasonic system is optimised to reliably detect objects at a depth exceeding 9 m while still obtaining a good resolution. Modelling studies show the potential of further increasing the distance between individual transducer arrays. Additionally, a new ultrasonic borehole probe using phased arrays allowing for beam focussing is constructed and tested. Laboratory measurements at a halfcylindrical concrete specimen coincide well with the previous modelling. In total, the presented safe materials, detailed monitoring approaches and ultrasonic quality assurance methods will help to obtain safe sealing structures within salt as a host rock. The concepts can partly be transferred to sealing structures in alternative host rocks and will also be valuable for non-nuclear waste repositories. T2 - NDE NucCon CY - Espoo, Finland DA - 25.01.2023 KW - SealWasteSafe KW - Engineered barriers KW - Monitoring KW - Embedded sensors KW - Ultrasonic imaging PY - 2023 SP - 2 EP - 10 AN - OPUS4-56928 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Lay, Vera A1 - Baensch, Franziska A1 - Johann, Sergej A1 - Sturm, Patrick A1 - Mielentz, Frank A1 - Prabhakara, Prathik A1 - Hofmann, Detlef A1 - Niederleithinger, Ernst A1 - Kühne, Hans-Carsten T1 - SealWasteSafe: materials technology, monitoring techniques, and quality assurance for safe sealing structures in underground repositories N2 - Within the project SealWasteSafe, we advance construction materials and monitoring concepts of sealing structures applied for underground disposal of nuclear or toxic waste. As these engineered barriers have high demands concerning integrity, an innovative alkali-activated material (AAM) is improved and tested on various laboratory scales. This AAM has low reaction kinetics related to a preferential slow release of the heat of reaction in comparison to alternative salt concretes based on Portland cement or magnesium oxychloride cements. Hence, crack formation due to thermally induced strain is reduced. After successful laboratory scale analysis (Sturm et al., 2021), the AAM is characterised on a larger scale by manufacturing test specimens (100–300 L). Conventional salt concrete (DBE, 2004) and the newly developed AAM are compared using two specimen geometries, i.e. cylindrical and cuboid. A comprehensive multisensor monitoring scheme is developed to compare the setting process of AAM and salt concrete for these manufactured specimens. The analysed parameters include temperature and humidity of the material, acoustic emissions, and strain variations. Passive sensor systems based on radiofrequency identification technology (RFID) embedded in the concrete, enable wireless access to temperature and humidity measurements and are compared to conventional cabled systems. Additionally, fibre-optic sensors (FOS) are embedded to record strain, but also have potential to record temperature and moisture conditions. Part of this project aims at demonstrating the high reliability of sensors and also their resistance to highly alkaline environments and to water intrusion along cables or at sensor locations. Further technical improvements were implemented so that first results clearly show the scalability of the setting process from previous small-scale AAM experiments and particularly the high potential of the newly developed approaches. Furthermore, ultrasonic methods are used for quality assurance to detect obstacles, potential cracks and delamination. On the one hand, both active and passive ultrasonic measurements complement the results obtained from the multisensor monitoring scheme for the produced specimens. On the other hand, the unique large aperture ultrasonic system (LAUS) provides great depth penetration (up to nearly 10 m) and can thus be applied at in situ sealing structures built as a test site in Morsleben by the Federal Company for Radioactive Waste Disposal (Bundesgesellschaft für Endlagerung, BGE) as shown by Effner et al. (2021). An optimised field lay-out identified from forward modelling studies and advanced imaging techniques applied to the measured data will further improve the obtained results. To characterise the inside of the test engineered barrier and achieve a proof-of-concept, an ultrasonic borehole probe is developed to enable phased arrays that can further improve the detection of potential cracks. Modelling results and first analysis of semispherical specimens confirmed the reliability of the directional response caused by the phased arrays of the newly constructed ultrasonic borehole probe. Overall, the project SealWasteSafe improves the construction material, multisensor monitoring concepts and ultrasonics for quality assurance. This will help to develop safe sealing structures for nuclear waste disposal. The outcomes are particularly valuable for salt as a host rock but partly also transferrable to alternative conditions. T2 - Safe ND Interdisciplinary research symposium on the safety of nuclear disposal practices CY - Berlin, Germany DA - 10.11.2021 KW - Borehole probe KW - SealWasteSafe KW - Engineered barrier KW - Materials technology KW - Monitoring KW - AAM KW - Ultrasound PY - 2021 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-539172 DO - https://doi.org/10.5194/sand-1-127-2021 VL - 1 SP - 127 EP - 128 PB - Copernicus AN - OPUS4-53917 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -