TY - CONF A1 - Hille, Falk T1 - Damage monitoring on OWT structures T2 - BAM-DTU Workshop on Design and maintenance of support structures for Offshore Wind Converters CY - Copenhagen, Denmark DA - 2011-10-25 PY - 2011 AN - OPUS4-24736 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Viefhues, Eva A1 - Döhler, M. A1 - Hille, Falk A1 - Mevel, L. T1 - Stochastic subspace-based damage detection with uncertainty in the reference null space N2 - This paper deals with uncertainty considerations in damage diagnosis using the stochastic subspace-based damage detection technique. With this method, a model is estimated from data in a (healthy) reference state and confronted to measurement data from the possibly damaged state in a hypothesis test. Previously, only the uncertainty related to the measurement data was considered in this test, whereas the uncertainty in the estimation of the reference model has not been considered. We derive a new test framework, which takes into account both the uncertainties in the estimation of the reference model as well as the uncertainties related to the measurement data. Perturbation theory is applied to obtain the relevant covariances. In a numerical study the effect of the new computation is shown, when the reference model is estimated with different accuracies, and the performance of the hypothesis tests is evaluated for small damages. Using the derived covariance scheme increases the probability of detection when the reference model estimate is subject to high uncertainty, leading to a more reliable test. T2 - International Workshop on Structural Health Monitoring CY - Stanford, CA, USA DA - 12.09.2017 KW - Subspace-methods KW - Uncertainty KW - Damage detection PY - 2017 SN - 978-1-60595-330-4 SP - 1007 EP - 1014 AN - OPUS4-42731 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Unger, Jörg F. A1 - Gründer, Klaus-Peter A1 - Hille, Falk A1 - Liehr, Sascha A1 - Maack, Stefan A1 - Niederleithinger, Ernst A1 - Pirskawetz, Stephan A1 - Rogge, Andreas A1 - Said, Samir A1 - Viefhues, Eva A1 - Zorn, Sebastian ED - Baeßler, Matthias ED - Möller, G. ED - Rogge, Andreas ED - Schiefelbein, N. T1 - Innovative Messsysteme zum Brückenmonitoring am Beispiel einer Versuchsbrücke – vom Sensor bis zur Zustandsprognose N2 - In der aktuellen Projektphase liegt der Fokus auf der Datenaufnahme, -bearbeitung und -speiche-rung mit dem Ziel, automatisierte Auswerteverfahren einsetzen zu können. Aktuell wurden primär punktuelle Messungen an ausgewählten Messtagen aufgenommen. Die Systeme sollen so weiter-entwickelt werden, dass sie sich auch für kontinuierliche Messungen im Rahmen von Monitoring-aufgaben eignen. Ein wichtiger Fokus bei der Auswertung ist die Kombination mit numerischen Modellen, die mithilfe von Bayesian Update Verfahren und den aufgenommenen Messdaten kalibriert und im Verlauf der Monitoringaufgabe angepasst werden sollen. Insbesondere sollen auch zeitabhängige Modelle, die eine zeitliche Entwicklung von Struktureigenschaften beinhalten (Kriechen, Schwinden, Ermüdung, Korrosion) dazu verwendet werden, die zukünftige Performance der Struktur bewerten zu können. Basierend darauf werden dann Konzepte zur Planung von Inspektion und Wartung erstellt. T2 - Messen im Bauwesen 2017 CY - Berlin, Germany DA - 14.11.2017 KW - Brückeninfrastruktur KW - Innovative Messverfahren KW - Stereofotogrammetrie PY - 2017 SN - 978-3-9818270-8-8 VL - 2017/1 SP - 7 EP - 19 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-44306 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hille, Falk T1 - Subspace-based Damage Detection Methods on a Prestressed Concrete Bridge T2 - EURODYN 2011, "The 8th International Conference on Structural Dynamics" CY - Leuven, Belgium DA - 2011-07-04 PY - 2011 AN - OPUS4-24579 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hille, Falk T1 - Long Term Monitoring of Real Structures T2 - SAMCO Summer Academy CY - Cambridge, England DA - 2003-07-16 PY - 2003 AN - OPUS4-4232 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Döhler, M. A1 - Hille, Falk A1 - Mevel, L. A1 - Rücker, Werner ED - Chang, F.-K. T1 - Structural health monitoring during progressive damage test of S101 bridge N2 - For the last decades vibration based identification of damage on civil Engineering structures has become an important issue for maintenance operations on transport infrastructure. Research in that field has been rapidly expanding from classic modal Parameter estimation using measured excitation to modern operational monitoring. Here the difficulty is to regard to the specific environmental and operational influence to the structure under observation. In this paper, two methods accounting for statistical and/or operational uncertainties are applied to measurement data of a progressive damage test on a prestressed concrete bridge. On the base of covariance driven Stochastic Subspace Identification (SSI) an algorithm is developed to monitor and automatically compute confidence intervals of the obtained modal parameters. Furthermore, a null space based non-parametric damage detection method, utilizing a statistical χ2 type test is applied to the measurement data. It can be shown that for concrete bridges the proposed methodology is able to clearly indicate the presence of structural damage, if the damage leads to a change of the structural system. T2 - 8th International workshop on structural health monitoring 2011 CY - Stanford, CA, USA DA - 13.09.2011 KW - Subspace identification KW - Damage detection KW - Convidence intervals KW - Prestressed concrete bridge PY - 2011 SN - 978-1-60595-053-2 VL - 1 SP - 748 EP - 758 PB - DEStech Publications, Inc. AN - OPUS4-24688 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hille, Falk A1 - Döhler, M. A1 - Mevel, L. A1 - Rücker, Werner ED - De Roeck, G. ED - Degrande, G. ED - Lombaert, G. ED - Müller, G. T1 - Subspace-based damage detection methods on a prestressed concrete bridge N2 - For the last decades vibration based damage detection of engineering structures has become an important issue for maintenance operations on transport infrastructure. Research in vibration based structural damage detection has been rapidly expanding from classic modal parameter estimation to modern operational monitoring. Methodologies from control Engineering especially of aerospace applications have been adopted and converted for the application on civil structures. Here the difficulty is to regard to the specific environmental and operational influence to the structure under observation. A null space based damage detection algorithm is tested for its sensitivity to structural damage of a prestressed concrete road bridge. Specific techniques and extensions of the algorithm are used to overcome difficulties from the size of the structure which is associated with the number of recorded sensor channels as well as from the operational disturbances by a nearby construction site. It can be shown that for concrete bridges the proposed damage detection methodology is able to clearly indicate the presence of structural damage, if the damage leads to a significant change of the structural system. Small damage which do not result in a System change when not activated by loading, do not lead to a modification of the dynamic response behavior and for that cannot be detected with the proposed global monitoring method. T2 - EURODYN 2011 - 8th International conference on structural dynamics CY - Leuven, Belgium DA - 04.07.2011 KW - Subspace methods KW - Fault detection KW - Monitoring techniques KW - Concrete bridge PY - 2011 SN - 978-90-760-1931-4 IS - MS12 TUE 11:45 SP - 2304 EP - 2310 AN - OPUS4-24689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hille, Falk A1 - Said, Samir A1 - Schmid, Wolfgang T1 - Lasteinwirkung- und Zustandsüberwachung von großen Spannbetonbrücken N2 - Die dauerhafte messtechnische Überwachung von Brückenbauwerken ist nach wie vor eine neuartige Verfahrensweise zur Bestimmung des Ist-Zustandes von Tragwerken. Der Fachbereich 7.2 Ingenieurbau der BAM befasst sich seit mittlerweise mehr als 25 Jahren mit der Entwicklung von Methoden und Verfahren dieser Form der Bauwerksüberwachung. Die damit verbundene Tätigkeit umfasst die Beschreibung theoretischer Grundlagen, die Entwicklung von Algorithmen zur Erfassung, Bearbeitung und Auswertung von Messsignalen, die Bewertung der Ergebnisse bezüglich Tragsicherheit, Gebrauchstauglichkeit und Restnutzungsdauer und nicht zuletzt die Untersuchung und Verifizierung der praktischen Anwendbarkeit. Dabei standen insbesondere die sogenannten dynamischen Verfahren im Blickpunkt der Aktivitäten. Ursprünglich zur Überwachung von rotierenden Maschinenkomponenten entwickelt und dann auch erfolgreich zur Überwachung von Bauteilen der Flugzeug-, Raumfahrt- und Automobilindustrie weiterentwickelt, weckten diese Verfahren weltweit das Interesse der sich mit der Sicherheit bestehender Baukonstruktionen befassenden Wissenschaftler und Ingenieure. Ein beachtenswertes Projekt der BAM in diesem Zusammenhang ist die Dauerüberwachung der Westendbrücke in Berlin, das Mitte der 90er Jahre von der damaligen Senatsverwaltung für Stadtentwicklung von Berlin (ehemals Bauen, Wohnen und Verkehr) in Auftrag gegeben und über viele Jahre gefördert wurde. Im Rahmen dieses Aufsatzes werden am Beispiel dieses Projektes, das sich wie ein roter Faden durch die Entwicklungsgeschichte des Monitorings an der BAM zieht, die Motivationen und Zielstellungen dargelegt, das Überwachungssystem vorgestellt und die gemachten Erfahrungen anhand einiger Ergebnisse erläutert. In einem weiteren Kapitel wird ein Ausblick auf die Zukunft des Monitorings mit angepassten Zielvorstellungen, neuen Methodiken und Strategien geworfen. T2 - Messen im Bauwesen 2013 - Ingenieuraufgaben und messtechnische Lösungen CY - Berlin, Germany DA - 12.03.2013 KW - Structural health monitoring KW - Spannbetonbrücken KW - Westendbrücke PY - 2013 SN - 978-3-9815360-5-8 SP - 107 EP - 119 AN - OPUS4-28070 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hille, Falk T1 - Lasteinwirkungs- und Zustandsüberwachung von großen Spannbetonbrücken T2 - Messen im Bauwesen 2013 CY - Berlin, Germany DA - 2013-03-12 PY - 2013 AN - OPUS4-28026 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Döhler, Michael A1 - Mevel, L. A1 - Hille, Falk T1 - Subspace-based damage detection under changes in the ambient excitation statistics N2 - In the last ten years, monitoring the integrity of the civil infrastructure has been an active research topic, including in connected areas as automatic control. It is common practice to perform damage detection by detecting changes in the modal parameters between a reference state and the current (possibly damaged) state from measured vibration data. Subspace methods enjoy some popularity in structural engineering, where large model orders have to be considered. In the context of detecting changes in the structural properties and the modal parameters linked to them, a subspace-based fault detection residual has been recently proposed and applied successfully, where the estimation of the modal parameters in the possibly damaged state is avoided. However, most works assume that the unmeasured ambient excitation properties during measurements of the structure in the reference and possibly damaged condition stay constant, which is hardly satisfied by any application. This paper addresses the problem of robustness of such fault detection methods. It is explained why current algorithms from literature fail when the excitation covariance changes and how they can be modified. Then, an efficient and fast subspace-based damage detection test is derived that is robust to changes in the excitation covariance but also to numerical instabilities that can arise easily in the computations. Three numerical applications show the efficiency of the new approach to better detect and separate different levels of damage even using a relatively low sample length. KW - Damage detection KW - Structural vibration monitoring KW - Ambient excitation KW - Subspace methods KW - Hypothesis testing PY - 2014 DO - https://doi.org/10.1016/j.ymssp.2013.10.023 SN - 0888-3270 VL - 45 IS - 1 SP - 207 EP - 224 PB - Elsevier Ltd. CY - London AN - OPUS4-29899 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CHAP A1 - Döhler, Michael A1 - Hille, Falk A1 - Mevel, L. A1 - Rücker, Werner T1 - Estimation of modal parameters and their uncertainty bounds from subspace-based system identification N2 - An innovative and efficient algorithm to estimate the modal Parameters and their uncertainties from subspace-based System identification has been developed. Applications to Output only measurements have been demonstrated on the S101 Bridge case. PY - 2013 SN - 978-3-200-03179-1 IS - Chapter 5 SP - 91 EP - 106 CY - Vienna, Austria AN - OPUS4-29906 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hille, Falk T1 - State of the Art in Monitoring and Assessment of Structures T2 - IRIS-NERA Summer Academy 2013 CY - Zell am See, Austria DA - 2013-09-02 PY - 2013 AN - OPUS4-29758 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Döhler, Michael A1 - Mevel, L. A1 - Hille, Falk T1 - Efficient computation of minmax tests for fault isolation and their application to structural damage localization N2 - Fault detection and isolation can be handled by many different approaches. This paper builds upon a hypothesis test that checks whether the mean of a Gaussian random vector has become non-zero in the faulty state, based on a chi2 test. For fault isolation, it has to be decided which components in the parameter set of the Gaussian vector have changed, which is done by variants of the chi2 hypothesis test using the so-called sensitivity and minmax approaches. While only the sensitivity of the tested parameter component is taken into account in the sensitivity approach, the sensitivities of all parameters are used in the minmax approach, leading to better statistical properties at the expense of an increased computational burden. The computation of the respective test variable in the minmax test is cumbersome and may be ill-conditioned especially for large parameter sets, asking hence for a careful numerical evaluation. Furthermore, the fault isolation procedure requires the repetitive calculation of the test variable for each of the parameter components that are tested for a change, which may be a significant computational burden. In this paper, dealing with the minmax problem, we propose a new efficient computation for the test variables, which is based on a simultaneous QR decomposition for all parameters. Based on this scheme, we propose an efficient test computation for a large parameter set, leading to a decrease in the numerical complexity by one order of magnitude in the total number of parameters. Finally, we show how the minmax test is useful for structural damage localization, where an asymptotically Gaussian residual vector is computed from output-only vibration data of a mechanical or a civil structure. T2 - 19th World congress of the international federation of automatic control CY - Cape Town, South Africa DA - 24.08.2014 KW - Fault isolation KW - Residual evaluation KW - Statistical tests KW - Numerical computation KW - Mechanical systems PY - 2014 SP - 7382 EP - 7387 PB - IFAC AN - OPUS4-31573 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Herrmann, Ralf A1 - Hille, Falk A1 - Said, Samir A1 - Sterthaus, Jens A1 - Müller, Karsten A1 - Quercetti, Thomas A1 - Wille, Frank A1 - Paffenholz, J.-A. A1 - Baeßler, Matthias ED - Papadrakakis, M. ED - Fragiadakis, M. ED - Papadimitriou, C. T1 - Implementing a Structural Health Monitoring system using digital models of the BAM large drop test facility in Horstwalde N2 - At the Bundesanstalt für Materialforschung und -prüfung (BAM) full scale specimens for nuclear transport and storage containers (casks) are tested for their structural integrity in a series of drop tests on the Test Site Technical Safety in Horstwalde, 50 km south of Berlin. These drop tests cause a major stress not only on the casks, but also on the steel tower structure of the test facility, itself. The load pattern makes the structure very interesting for detailed investigation. The focus of the monitoring lies on the bolted joints of the flange connections that are a typical connection for cylindrical elements if welding is technical or economical unfavorable. The definition of the monitoring takes was done by investigating the existing documents and inspection results accompanied by building an initial digital representation of the structure, consisting of two finite element (FE) models and a geometrical 3D point cloud representation. As a first step the structures behavior during static and dynamic loading was analyzed using measurement data and an updated numerical FE Model. The idea behind is to use models for a digital planning and operation/evaluation of the structural health monitoring. A static FE simulation and a dynamic FE simulation are generated, to investigate how the structure behaves under the load conditions. T2 - XI International Conference on Structural Dynamics (EuroDyn 2020) CY - Online meeting DA - 23.11.2020 KW - Structural Health Monitoring KW - Drop Tests KW - System Identification KW - Digital Models KW - BIM PY - 2020 UR - https://generalconferencefiles.s3-eu-west-1.amazonaws.com/eurodyn_2020_ebook_procedings_vol1.pdf SN - 978-618-85072-0-3 VL - 1 SP - 1293 EP - 1304 PB - Institute of Structural Analysis and Antiseismic Research CY - Athen AN - OPUS4-51592 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -