Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-28728 Beitrag zu einem Tagungsband Thöns, Sebastian; Faber, M.H. Deodatis, G.; Ellingwood, B.R.; Frangopol, D.M. Assessing the value of structural health monitoring Structural Health Monitoring (SHM) systems are designed for assisting owners and operators with information and forecasts concerning the fitness for purpose of structures and building systems. The benefit associated with the implementation of SHM may in some cases be intuitively anticipated or proven by past experiences but in general there appears to be no rational or systematic approach for assessing the value of SHM systems a-priory to their implementation. The present paper addresses the assessment of the value of SHM with basis in structural risk assessments and the Bayesian pre-posterior decision analysis. The quantification of the value of SHM builds upon the quantification of the value of information (VoI) or rather the benefit of monitoring. The suggested approach involves a probabilistic representation of the loads and environmental conditions acting on structures as well as their responses and performances over their life-cycle. In addition, the quality of monitoring and the performance of possible remedial actions triggered by monitoring results are modeled probabilistically.The consequences accounted for, in principle include all consequences associated with the performance of the structure over its life-cycle as well as the costs associated with monitoring and possible remedial actions. The suggested approach is illustrated through two case studies concerning the monitoring of welded details in steel structures subjected to fatigue loading. The case studies address the effect of the uncertainty associated with the performance of SHM on the value of SHM. Moreover, in order to illustrate the potential of the application of approach for monitoring of structural systems an optimal strategy for SHM is determined for a system comprised of three welded details. Leiden, The Netherlands CRC Press 2013 ICOSSAR'13 - 11th International conference on structural safety and reliability - Safety, reliability, risk and life-cycle performance of structures and infrastructures (Proceedings) 978-1-138-00086-5 11th International conference on structural safety and reliability - Safety, reliability, risk and life-cycle performance of structures and infrastructures New York, USA 16.06.2013 20.06.2013 1 8 2016-02-20 OPUS4-28729 Beitrag zu einem Tagungsband Thöns, Sebastian; Lanata, F. Deodatis, G.; Ellingwood, B.R.; Frangopol, D.M. Risk and operation optimized damage detection and inspection systems Leiden, The Netherlands CRC Press 2013 ICOSSAR'13 - 11th International conference on structural safety and reliability - Safety, reliability, risk and life-cycle performance of structures and infrastructures (Proceedings) 978-1-138-00086-5 11th International conference on structural safety and reliability - Safety, reliability, risk and life-cycle performance of structures and infrastructures New York, USA 16.06.2013 20.06.2013 1 10 2016-02-20 OPUS4-26181 Beitrag zu einem Tagungsband Thöns, Sebastian; Döhler, M. Del Grosso, A.E.; Basso, P. Structural reliability updating with stochastic subspace damage detection information Erredi Grafiche Editoriali European association for the control of structures (EACS) 2012 EACS 2012 - Smart structures - 5th European conference on structural control (Proceedings) 978-88-95023-13-7 EACS 2012 - Smart structures - 5th European conference on structural control Genoa, Italy 2012-06-18 2012-06-20 Paper #008 1 12 2016-02-19 OPUS4-26358 Zeitschriftenartikel Thöns, Sebastian; Faber, M.H.; Rücker, Werner Ultimate limit state model basis for assessment of offshore wind energy converters This paper establishes the model basis regarding the ultimate limit state consisting of structural, loading, and probabilistic models of the support structure of offshore wind energy converters together with a sensitivity study. The model basis is part of a risk based assessment and monitoring framework and will be applied for establishing the 'as designed and constructed' reliability as prior information for the assessment and as a basis for designing a monitoring system. The model basis is derived considering the constitutive physical equations and the methodology of solving these which then in combination with the ultimate limit state requirements leads to the specific constitutive relations. As a result finite element models based on shell elements incorporating a structural and a loading model are introduced and described in detail. Applying these models the ultimate capacity of the support structure and the tripod structure are determined with a geometrically and materially nonlinear finite element analysis. The observed failure mechanisms are the basis for the definition of the ultimate limit state responses. A probabilistic model accounting for the uncertainties involved is derived on the basis of literature review and measurement data from a prototype Multibrid M5000 support structure. In combination with the developed structural and loading models, sensitivity analyses in regard to the responses are performed to enhance the understanding and to refine the developed models. To this end, as the developed models necessitate substantial numerical efforts for the probabilistic response analysis predetermined designs of numerical experiments are applied for the calculation of the sensitivities using the Spearman rank correlation coefficient. With this quantification of the sensitivity of the random variables on the responses including nonlinearity the refinement of the model is performed on a quantitative basis. Fairfield, NJ American Society of Mechanical Engineers (ASME) 2012 Journal of offshore mechanics and arctic engineering 134 3 031904-1 - 031904-9 10.1115/1.4004513 2016-02-19 OPUS4-28280 Dissertation Thöns, Sebastian Monitoring based condition assessment of offshore wind turbine support structures Basel vdf Hochschulverlag AG, Zürich ETH Zürich, Institut für Baustatik und Konstruktion 2012 IBK Bericht 345 1 149 10.3929/ethz-a-009753058 2016-02-20 OPUS4-25076 Beitrag zu einem Tagungsband Grasse, Fabian; Trappe, Volker; Thöns, Sebastian; Said, Samir De Roeck, G.; Degrande, G.; Lombaert, G.; Müller, G. Structural health monitoring of wind turbine blades by strain measurement and vibration analysis Wind turbine blades have to withstand a high number of load cycles in mostly hard weather conditions over 20 years. In a research project BAM and several partners have designed, evaluated and tested a condition monitoring system for all parts of a wind turbine. At a rotorblade with a length of 58 m fibre bragg grating sensors were applied for in-service strain measurement. Additionally a complex test rig was designed to enable real biaxial loading conditions at a representative test rotor blade to simulate the mechanical loading conditions in the lab. In this test blade with a length of 8 m also fibre bragg grating sensors were implemented to determine their influences for the structure and the condition monitoring system. Vibration measurements were carried out at different test phases. The results were compared with finite element strain and modal analysis. Katholieke Universiteit Leuven 2011 EURODYN 2011 - 8th International conference on structural dynamics (Proceedings) 978-90-760-1931-4 EURODYN 2011 - 8th International conference on structural dynamics Leuven, Belgium 04.07.2011 06.07.2011 MS25 Tue 3490 3497 2016-02-19 OPUS4-16280 Beitrag zu einem Tagungsband Rohrmann, Rolf; Rücker, Werner; Thöns, Sebastian Integrated Monitoring Systems for Offshore Wind Turbines 2007 6th International Workshop on Structural Health Monitoring, September 11-13, 2007, Stanford, USA (Proceedings) 6th International Workshop on Structural Health Monitoring Stanford, USA 2007-09-11 2007-09-13 1 8 2016-02-19 OPUS4-18565 Beitrag zu einem Sammelband Thöns, Sebastian; Faber, M.H.; Rücker, Werner; Rohrmann, Rolf Martorell, S.; et al., Assessment and monitoring of reliability and robustness of offshore wind energy converters London, UK Taylor & Francis 2008 Safety, Reliability and Risk Analysis: Theory, Methods and Applications 978-0-415-48513-5 ESREL 2008 Valencia, Spain 2008-09-22 2008-09-25 1567 1572 2016-02-19 OPUS4-28984 Beitrag zu einem Tagungsband Schneider, Ronald; Thöns, Sebastian; Rücker, Werner; Straub, D. Deodatis, G.; Ellingwood, B.R.; Frangopol, D.M. Effect of different inspections strategies on the reliability of Daniels systems subjected to fatigue Inspections are an efficient means of enhancing the reliability of redundant structural Systems subjected to fatigue. To investigate the effect of such inspections, we represent the deterioration state of a Daniels System by means of a probabilistic fatigue crack growth model of all elements, which considers stochastic dependence among element fatigue behavior. We include inspection results in the calculation of the System collapse probability through Bayesian updating of the System deterioration state. Based on this approach, we calculate the collapse probability of a deteriorating Daniels System conditional on different inspection strategies in terms of inspection coverage and inspection times. The acceptability of an inspection strategy is verified by comparing the calculated collapse probabilities with maximum acceptable System failure probabilities. This study is a Step towards identifying optimal inspection strategies for redundant structural Systems subjected to fatigue. Leiden, The Netherlands CRC Press 2013 ICOSSAR'13 - 11th International conference on structural safety and reliability - Safety, reliability, risk and life-cycle performance of structures and infrastructures (Proceedings) 978-1-138-00086-5 11th International conference on structural safety and reliability - Safety, reliability, risk and life-cycle performance of structures and infrastructures New York, USA 16.06.2013 20.06.2013 1 8 2016-02-20 OPUS4-29103 Buchkapitel Thöns, Sebastian; Faber, M.H.; Rücker, Werner Life cycle cost optimized monitoring systems for offshore wind turbine structures Monitoring information should be utilized to support optimal decisions. In this sense monitoring systems should be designed such as to optimize expected Life Cycle Costs. Vienna, Austria Vienna consulting engineers ZT GmbH 2013 IRIS Industrial safety and life cycle engineering - Technologies / Standards / Applications 978-3-200-03179-1 Chapter 4 75 90 2016-02-20 OPUS4-29104 Beitrag zu einem Tagungsband Rücker, Werner; Thöns, Sebastian; Said, Samir; Schmid, Wolfgang Zingoni, A. SHM strategies, application and measurements on tripod offshore wind energy converters within the German offshore park Alpha Ventus Prototypes of wind turbines of the megawatt dass are to be built and tested until 2008 within a German offshore wind energy test field in the North Sea (ALPHA VENTUS). To ensure a high operational reliability of offshore wind turbines with economically acceptable repair and maintenance efforts, comprehensive diagnosis and supervision concepts are required. Automatic monitoring Systems will be an essential part of such concepts. Because of the fact, that during Operation there will be static and dynamic interaction between the components 'structure', 'machinery' and 'blades' it is necessary to develop the monitoring techniques in an overall concept. These monitoring Systems are supposed to be applied for the design and testing as well as for the Operation and maintenance phases. In the paper the developed approaches for the measurement of actions and the condition monitoring of all components of an offshore wind energy plant will be shown. CRC Press 2013 Research and applications in structural engineering, mechanics and computation - 5th International conference on structural engineering, mechanics and computation (Proceedings) 978-1-138-00061-2 Research and applications in structural engineering, mechanics and computation - 5th International conference on structural engineering, mechanics and computation Cape Town, South Africa 02.09.2013 04.09.2013 977 982 2016-02-20 OPUS4-21666 Beitrag zu einem Tagungsband Thöns, Sebastian; Rücker, Werner; Faber, M.H. Support structure reliability of offshore wind turbines utilizing an adaptive response surface method American Society of Mechanical Engineers (ASME) 2010 OMAE 2010 - 29th International conference on ocean, offshore and arctic engineering OMAE 2010 - 29th International conference on ocean, offshore and arctic engineering Shanghai, China 2010-06-06 2010-06-11 OMAE2010-20546 1 10 2016-02-19 OPUS4-27067 Beitrag zu einem Tagungsband Schneider, Ronald; Thöns, Sebastian; Straub, D. Strauss, A.; Frangopol, D.M.; Bergmeister, K. Probalistic fatigue crack growth modeling for reliability-based inspection planning The fatigue deterioration modeling for welded steel structures subjected to high cycle fatigue is presented in the current document. The aim of this paper is to formulate approaches based on actual Research results for the phases fatigue crack initiation, fatigue propagation and fatigue failure. The physical characteristics of the approaches are discussed in combination with the associated uncertainties and the probabilistic modeling of this time variant reliability problem. The fatigue deterioration modeling documented here serve as a basis for a reliability-based approach to inspection planning. CRC Press 2012 Life-cycle and sustainability of civil infrastructure systems 978-0-415-62126-7 3rd International symposium on life-cycle civil engineering Vienna, Austria 03.10.2012 06.10.2012 319 326 2016-02-19 OPUS4-27068 Beitrag zu einem Tagungsband Schneider, Ronald; Thöns, Sebastian; Straub, D. Strauss, A.; Frangopol, D.M.; Bergmeister, K. Reliability-based inspection planning with application to orthotropic bridge deck structures subjected to fatigue A reliability-based approach to inspection planning for welded steel structures subjected to high cycle fatigue is presented in the current document. Inspections are an effective means to control the Progress of fatigue deterioration and the presented approach allows to determine the minimum required inspection effort so that the considered structure complies with the given risk acceptance criteria in terms of target reliability throughout its service life. CRC Press 2012 Life-cycle and sustainability of civil infrastructure systems 978-0-415-62126-7 3rd International symposium on life-cycle civil engineering Vienna, Austria 03.10.2012 06.10.2012 311 318 2016-02-19 OPUS4-26117 Beitrag zu einem Tagungsband Thöns, Sebastian; McMillan, D. Condition monitoring benefit for offshore wind turbines Istanbul technical university 2012 PMAPS 2012 - 12th International conference on Probabilistic Methods Applied to Power Systems (Proceedings) PMAPS 2012 - 12th International conference on Probabilistic Methods Applied to Power Systems Istanbul, Turkey 2012-06-10 2012-06-14 37 42 2016-02-19 OPUS4-26437 Zeitschriftenartikel Thöns, Sebastian; Faber, M.H.; Rücker, Werner Fatigue and serviceability limit state model basis for assessment of offshore wind energy converters This paper develops the models for the structural performance of the loading and probabilistic characterization for the fatigue and the serviceability limit states for the support structure of offshore wind energy converters. These models and a sensitivity study are part of a risk based assessment and monitoring framework and will be applied for establishing the 'as designed and constructed' reliability as prior information for the assessment and the design of monitoring systems. The constitutive physical equations are introduced in combination with the fatigue and serviceability limit state requirements as the starting point for the development of the structural performance and loading models. With these models introduced in detail, several modeling aspects for both limit states are analyzed. This includes analyses of the influence on the hot spot stresses by applying a contact formulation for the pile guide brace connection and the application of a finite element formulation using solid elements. Further, the comparison of the natural frequencies of a discrete rotor model with a continuous rotor model is documented. To account for uncertainties associated with the structural and loading models, a probabilistic model is derived on the basis of literature review and measurement data from a prototype Multibrid M5000 support structure. The sensitivity study is based on the calculation of a nonlinear coefficient of correlation in conjunction with predetermined designs of experiments. This is conducted by a systematic analysis of the influence of the random variables on limit state responses and hence on the structural reliability. Integrating the analyses and sensitivity studies of the fatigue and serviceability limit state models developed in this paper as well as the ultimate limit state models in Thöns et al. ('Ultimate Limit State Model Basis for Assessment of Offshore Wind Energy Converters,' ASME J. Offshore Mech. Arct. Eng.), the model basis for the assessment is completed. The process of establishing and analyzing such a model basis contributes to a detailed understanding of the deterministic and probabilistic characteristics of the structure and provides valuable insights in regard to the significance of available data. Fairfield, NJ American Society of Mechanical Engineers (ASME) 2012 Journal of offshore mechanics and arctic engineering 134 3 031905-1 - 031905-10 10.1115/1.4004514 2016-02-19 OPUS4-29719 Beitrag zu einem Tagungsband Rabe, Frederik; Löhnert, Andrea; Knaust, Christian; Thöns, Sebastian Numerical quantification of fire smoke toxicity in tunnels Vehicle fires in tunnels can have catastrophic consequences for the road users, the property and traffic inffastructure. To support an evacuation planning, this study simulates the fire smoke toxicity and the smoke layer of a vehicle fire in a full-size test tunnel. The three dimensional prediction of the fire smoke toxicity in the test tunnel is realized by implementing the Fractional Effective Dose and the Fractional Summation concept in a CFD environment. The developed model facilitates to calculate fire scenarios for various types of tunnels and to quantify the hazard e.g. during an evacuation scenario. BHR Group 2013 ISAVFT 15 - 15th International symposium on aerodynamics, ventilation and fire in tunnels 978-1-85598-137-9 ISAVFT 15 - 15th International symposium on aerodynamics, ventilation and fire in tunnels Barcelona, Spain 18.09.2013 20.09.2013 203 215 2016-02-20 OPUS4-29894 Beitrag zu einem Tagungsband Faber, M.H.; Thöns, Sebastian Miraglia, S.; Vrouwenvelder, A.C.W.M.; Steenbergen, R.D.J.M.; Van Gelder, P.H.A.J.M. On the value of structural health monitoring Taylor & Francis 2014 22nd ESREL conference 2013 - Safety, reliability and risk analysis: Beyond the horizon 978-1-138-00123-7 22nd ESREL conference - Safety, reliability and risk analysis: Beyond the horizon Amsterdam, The Netherlands 2013-09-29 2013-10-02 2535 2544 2016-02-20 OPUS4-55165 Corrigendum Farhan, Muhammad; Schneider, Ronald; Thöns, Sebastian Corrigendum to Predictive information and maintenance optimization based on decision theory: a case study considering a welded joint in an offshore wind turbine support structure This article has been revised and republished due to substantial changes to the text of the original article, as published Online First on January 31, 2021. Most of the change were minor grammatical changes. The following changes are more significant and will be highlighted below. London Sage Publications 2022 Structural health monitoring 21 4 1956 1956 10.1177/14759217211040385 2022-07-04 OPUS4-53064 Zeitschriftenartikel Zhang, W.-H.; Qin, J.; Lu, D.-G.; Thöns, Sebastian; Havbro Faber, M. Vol-informed decision-making for SHM system arrangement Structural health monitoring systems have been widely implemented to provide real-time continuous data support and to ensure structural safety in the context of structural integrity management. However, the quantification of the potential benefits of structural health monitoring systems has not yet attracted widespread attention. At the same time, there is an urgent need to develop strategies, such as optimizing the monitoring period, monitoring variables, and other factors, to maximize the potential benefits of structural health monitoring systems. Considering the continuity of structural health monitoring information, a framework is developed in this article to support decision-making for structural Health monitoring systems arrangement in the context of structural integrity management, which integrates the concepts of value of information and risk-based inspection planning based on an approach which utilizes a conjugate prior probability distribution for updating of the probabilistic models of structural performances based on structural health Monitoring information. An example considering fatigue degradation of steel structures is investigated to illustrate the application of the proposed framework. The considered example shows that the choice of monitoring variables, the Monitoring period, and the monitoring quality may be consistently optimized by the application of the proposed framework and approach. Finally, discussions and conclusions are provided to clarify the potential benefits of the proposed Framework with a special view to practical applications of structural health monitoring systems. USA SAGE Journals 2020 Special Issue: SHM: A Value of Information Perspective Structural 21 1 37 58 10.1177/1475921720962736 2021-08-05 OPUS4-52171 Zeitschriftenartikel Long, Lijia; Alcover, I. F.; Thöns, Sebastian Utility analysis for SHM durations and service life extension of welds on steel bridge deck Optimization of the duration of Structural Health Monitoring (SHM) campaigns is rarely performed. This article provides a utility-based solution to posteriorly determine: i) optimal monitoring Durations and ii) the extension of the service life of the welds on a steel bridge deck. The approach is Illustrated with a case study focusing on remaining fatigue life estimation of the welds on the orthotropic steel deck of the Great Belt Bridge, in Denmark. The identification of the optimal monitoring duration and the decision about extending the service life of the welds are modelled by maximizing the expected benefits and minimizing the structural risks. The results are a parametric analysis, mainly on the effect of the target probability, benefit, cost of failure, cost of rehabilitation, cost of monitoring and Discount rate on the posterior utilities of monitoring strategies and the choice of service life considering the risk variability and the costs and benefits models. The results show that the decision on short-term monitoring, i.e., 1 week every six months, is overall the most valued SHM strategy. In addition, it is found that the target probability is the most sensitive parameter affecting the optimal SHM Durations and service life extension of the welds. Taylor Francis Online 2021 Structure and Infrastructure Engineering Maintenance, Management, Life-Cycle Design and Performance Latest Articles 18 4 492 504 urn:nbn:de:kobv:b43-521719 10.1080/15732479.2020.1866026 2021-03-01 OPUS4-52771 Zeitschriftenartikel Farhan, Muhammad; Schneider, Ronald; Thöns, Sebastian Predictive information and maintenance optimization based on decision theory: a case study considering a welded joint in an offshore wind turbine support structure Predictive information and maintenance optimization for deteriorating structures is concerned with scheduling (a) the collection of information by inspection and monitoring and (b) maintenance actions such as repair, replacement, and retrofitting based on updated predictions of the future condition of the structural system. In this article, we consider the problem of jointly identifying—at the beginning of the service life—the optimal inspection time and repair strategy for a generic welded joint in a generic offshore wind turbine structure subject to fatigue. The optimization is performed based on different types of decision analyses including value of information analyses to quantify the expected service life cost encompassing inspection, repair, and fatigue damage for all relevant combinations of inspection time, repair method, and repair time. Based on the analysis of the expected service life cost, the optimal inspection time, repair method, and repair time are identified. Possible repair methods for a welded joint in an offshore environment include welding and grinding, for which detailed models are formulated and utilized to update the joint's fatigue performance. The decision analyses reveal that an inspection should be scheduled approximately at mid-service life of the welded joint. A repair should be performed in the same year after an indication and measurement of a fatigue crack given an optimal inspection scheduling. This article concludes with a discussion on the results obtained from the decision and value of information analyses. London Sage Publications 2021 Structural health monitoring 10.1177/1475921720981833 2021-06-10 OPUS4-52798 Beitrag zu einem Tagungsband Kinne, Marko; Schneider, Ronald; Thöns, Sebastian Reconstructing Stress Resultants in Wind Turbine Towers Based on Strain Measurements Support structures of offshore wind turbines are subject to cyclic stresses generated by different time-variant random loadings such as wind, waves, and currents in combinationwith the excitation by the rotor. In the design phase, the cyclic demand on wind turbine support structure is calculated and forecasted with semi or fully probabilistic engineering models. In some cases, additional cyclic stresses may be induced by construction deviations, unbalanced rotor masses and structural dynamic phenomena such as, for example, the Sommerfeld effect. Both, the significant uncertainties in the design and a validation of absence of unforeseen adverse dynamic phenomena necessitate the employment of measurement Systems on the support structures. The quality of the measurements of the cyclic demand on the support structures depends on (a) the precision of the measurement System consisting of sensors, amplifier and data normalization and (b) algorithms for analyzing and converting data to structural health information. This paper presents the probabilistic modelling and analysis of uncertainties in strain measurements performed for the purposes of reconstructing stress resultants in wind turbine towers. It is shown how the uncertainties in the strain measurements affect the uncertainty in the individual components of the reconstructed forces and moments. The analysis identifies the components of the vector of stress resultants that can be reconstructed with sufficient precision. Springer 2021 International Conference on Uncertainty in Mechanical Engineering - ICUME Online meeting 07.06.2021 224 235 urn:nbn:de:kobv:b43-527987 10.1007/978-3-030-77256-7_18 https://creativecommons.org/licenses/by/4.0/deed.de 2021-06-10 OPUS4-31256 Beitrag zu einem Tagungsband Berchtold, Florian; Thöns, Sebastian; Knaust, Christian; Rogge, Andreas Review of road tunnel risk assessment - common aspects? Safety measures like tunnel emergency Ventilation Systems cause high financial costs. Hence, safety measures have to be chosen with the focus on the expected reduction of the consequences like fatalities or damage on structures and in conjunction with the investments. Since 2004, the European directive EU 2004/54/EC proposes therefore the application of risk assessments. Because the EU directive provides only few legal requirements on risk assessments, the methodologies developed on this basis have large differences. After one decade of intensive research, the comparative study now highlights common aspects and differences of several methodologies. 2014 6th International symposium on tunnel safety and security 6th International symposium on tunnel safety and security Marseille, France 12.03.2014 14.03.2014 669 670 2016-02-20 OPUS4-31275 Beitrag zu einem Sammelband Thöns, Sebastian; McMillan, D. Karki, R.; Billinton, R.; Vermar, A.K. Condition monitoring benefit for operation support of offshore wind turbines As more offshore wind parks are commissioned, the focus will inevitably shift from a planning, construction, and warranty focus to an operation, maintenance, and investment payback focus. In this latter case, both short-term risks associated with wind turbine component assemblies, and long-term risks related to integrity of the support structure, are highly important. This research focuses on the role of condition monitoring to lower costs and risks associated with short-term reliability and long-term asset integrity. This enables comparative estimates of the life cycle costs and reduction in uncertainty, both of which are of value to investors. Springer 2014 Reliability modeling and analysis of smart power systems 978-81-322-1797-8 169 182 10.1007/978-81-322-1798-5_11 2016-02-20 OPUS4-19872 Beitrag zu einem Tagungsband Rohrmann, Rolf; Rücker, Werner; Thöns, Sebastian; Said, Samir Design and operation of integrated monitoring systems for offshore wind turbines To ensure a high operational reliability of future generations of offshore wind conversion systems (OWEC) with economically acceptable repair and maintenance efforts, comprehensive diagnosis and supervision concepts are required. Automatic monitoring systems will be an essential part of such concepts. Because of the fact, that during operation there will be static and dynamic interaction between the components 'structure', 'machinery' and 'blades' it is necessary to develop the monitoring techniques in an overall concept. These monitoring systems are supposed to be applied for the design and testing as well as for the operation and maintenance phases. The used methods are focused on the design requirements for the structure, which are stated in the respective standards and certification guidelines. For the validation of the design, methods are specified which would be also applicable for SHM in the operating condition, e.g. for the evaluation of the structural conditon possibly after the occurrence of damages or changes. The further task consists in the realization of condition monitoring for all components, aiming at early damage detection and the observation of the damage development and its evaluation. Here the task consists of determining with assessment procedures the optimum time for maintenance actions to be carried out. BARD Engineering GmbH 2008 DEWEK 2008 - 9th German wind energy conference (Proceedings) DEWEK 2008 - 9th German wind energy conference Bremen, Germany 2008-11-26 2008-11-27 1 4(?) 2016-02-19 OPUS4-21452 Zeitschriftenartikel Rohrmann, Rolf; Thöns, Sebastian; Rücker, Werner Integrated monitoring of offshore wind turbines - requirements, concepts and experiences Wind turbines on offshore sites (OWECs) are subjected to combined loads from wind and waves. These dynamic loads, with a frequency content within the range of the natural frequencies of the structures, cause fatigue-effective stresses in the substructures of wind turbines. Therefore, the examination of natural frequencies is an important part within the design process of wind turbines. The quality of the numerical models for such calculations is of great importance, since the certification guidelines permit only small uncertainties in modal analysis results. The accuracy of the parameters of the numerical model can only be achieved through a comparison of simulation results with corresponding test results. Therefore, it is necessary to measure the dynamic behaviour of all components of the wind turbines simultaneously. This is true not only for the design verification, but also for monitoring the OWECs in operation. The potential of integrated systems for monitoring-based maintenance optimisation should thus be used. London Taylor & Francis 2010 Structure & infrastructure engineering 6 5 575 591 10.1080/15732470903068706 2016-02-19 OPUS4-23712 Beitrag zu einem Tagungsband Rohrmann, Rolf; Thöns, Sebastian; Rücker, Werner; Bicker, S.; Said, Samir; Schmid, Wolfgang Structural investigations and monitoring results on a prototype of offshore wind turbines of multibrid M5000 series The concept and technical details of the implementation of the developed integrated monitoring system within the IMO-WIND project are presented. The tasks of the components of the system and its requirements are described. Selected results from the continuous monitoring during operation of the plant M5000_2 regarding the task design verification and dynamic structural analysis are given. DEWI GmbH 2011 DEWEK 2010 - 10th German wind energy conference (Proceedings) DEWEK 2010 - 10th German wind energy conference Bremen, Germany 2010-11-17 2010-11-18 S03 1 5 2016-02-19 OPUS4-24292 Beitrag zu einem Tagungsband Thöns, Sebastian; Faber, M.H.; Rücker, Werner Faber, M.H.; Köhler, J.; Nishijima, K. On the utilization of monitoring data in an ultimate limit state reliability analysis This paper describes a structural reliability analysis utilizing monitoring data in the ultimate limit state with consideration of the uncertainties of the monitoring procedure. For this purpose the uncertainties of the monitoring data are modeled utilizing a new framework for the determination of measurement uncertainties. The approach is based on a process equation and Statistical models of observations for the derivation of a posterior measurement uncertainty by Bayesian updating. This facilitates the quantification of a measurement uncertainty using all available data of the measurement process. For the reliability analysis in the ultimate limit state, monitoring data can be utilized as a loading model Information and as proof loading, i.e. resistance model Information. Both approaches are discussed with generic examples and it is shown that the modeling of monitoring data in a reliability analysis can result in a reduction of uncertainties and as a consequence in the reduction of the probability of failure. Furthermore, the proof loading concept is developed further to account for the uncertain characteristic of proof loading due to the measurement uncertainties which is consistent with the framework for the determination of measurement uncertainties. These approaches and findings can be utilized for the assessment of structures for life cycle extension and the design of monitoring Systems. London Taylor & Francis 2011 ICASP 11 - 11th International conference on applications of statistics and probability in civil engineering 978-0-415-66986-3 ICASP 11 - 11th International conference on applications of statistics and probability in civil engineering Zurich, Switzerland 01.08.2011 04.08.2011 1762 1769 2016-02-19 OPUS4-24293 Beitrag zu einem Tagungsband Rohrmann, Rolf; Said, Samir; Schmid, Wolfgang; Thöns, Sebastian; Bicker, S.; Rücker, Werner De Roeck, G.; Degrande, G.; Lombaert, G.; Müller, G. Results from monitoring and assessment of offshore wind turbines To ensure a high operational reliability of offshore wind turbines (OWEC) with economically acceptable repair and maintenance efforts, comprehensive diagnosis and supervision concepts are required. Automatic monitoring Systems will be an essential part of such concepts. Because of the fact, that during Operation there will be static and dynamic interaction between the components 'structure', 'machinery' and 'blades' it is necessary to develop the monitoring techniques in an overall concept. These monitoring Systems are supposed to be applied for the design and testing as well as for the Operation and maintenance phases. The knowledge of the dynamic behavior of wind turbines is important both for the design and for a safe Operation. The available monitoring data from a period of three years, allow first conclusions on the long-term Operation of such Systems in terms of quality requirements to the instrumentation to the structure and the rotor blades Katholieke Universiteit Leuven 2011 EURODYN 2011 - 8th International conference on structural dynamics (Proceedings) 978-90-760-1931-4 EURODYN 2011 - 8th International conference on structural dynamics Leuven, Belgium 04.07.2011 06.07.2011 MS25 3450 3456 2016-02-19 OPUS4-38217 Zeitschriftenartikel Thöns, Sebastian; Schneider, Ronald The Influence of brittle Daniels system characteristics on the value of load monitoring information This paper addresses the influence of deteriorating brittle Daniels system characteristics on the value of structural health monitoring (SHM). The value of SHM is quantified as the difference between the life cycle benefits with and without SHM. A value of SHM analysis is performed within the framework of the Bayesian pre-posterior decision theory and requires (1) structural performance modelling and prediction, (2) structural integrity management models, (3) the (pre-posterior) modelling of SHM and (4) the coupling of SHM and the structural performance models. The pre-posterior decision theoretical framework facilitates that the value of SHM can be quantified before the SHM system is quantified and before data are acquired. The results of this study support decisions to select structural systems for which the SHM strategy load monitoring is optimal. Kirchwald NDT.net 2016 The e-journal of nondestructive testing & ultrasonics 21 8th European Workshop on Structural Health Monitoring (EWSHM 2016) Bilbao, Spain 05.07.2016 08.07.2016 8 1 9 2016-11-11 OPUS4-38218 Zeitschriftenartikel Schneider, Ronald; Thöns, Sebastian; Straub, Daniel Reliability analysis and updating of deteriorating systems with subset simulation An efficient approach to reliability analysis of deteriorating structural systems is presented, which considers stochastic dependence among element deterioration. Information on a deteriorating structure obtained through inspection or monitoring is included in the reliability assessment through Bayesian updating of the system deterioration model. The updated system reliability is then obtained through coupling the updated deterioration model with a probabilistic structural model. The underlying high-dimensional structural reliability problems are solved using subset simulation, which is an efficient and robust sampling-based algorithm suitable for such analyses. The approach is demonstrated in two case studies considering a steel frame structure and a Daniels system subjected to high-cycle fatigue. Elsevier 2017 Structural Safety 64 20 36 10.1016/j.strusafe.2016.09.002 2016-11-28 OPUS4-32878 Zeitschriftenartikel Hu, Wei-Hua; Thöns, Sebastian; Rohrmann, Rolf; Said, Samir; Rücker, Werner Vibration-based structural health monitoring of a wind turbine system. Part I: Resonance phenomenon This paper is focused on a resonance phenomenon of a wind turbine system in 5 MW class, on the basis of dynamic signals acquired continuously from the tubular tower under normal operational conditions during two years. Firstly, technique specifications of the wind turbine system are introduced and a finite element model is developed to characterize the structural dynamic properties. The following part describes the continuous dynamic monitoring system integrated with an automated operational modal analysis procedure using the poly-reference Least Squares Complex Frequency domain (p-LSCF) method. Subsequently, variations and mutual relationships of environmental/operational factors such as vibration amplitude, temperature, wind speed, rotation speed of blades, pitch angle and nacelle direction are also presented. Finally, significant resonance is observed due to the fundamental frequency of the tower matching with the harmonic frequency induced by the rotation of three blades. As the rotation speed of rotor approaches to 8 rpm, the vibration amplitude of the tower increases significantly and the corresponding damping value decreases. With the further rising wind velocity, the rotation speed of blades stops increasing and the input energy just contribute to accumulate the vibration amplitude of tower. Such observation indicates the Sommerfeld effect that aggravates the resonance phenomenon. A vibration control device is necessary to minimize the excessive structural responses. A companion paper will further discuss the environmental/operational effects on dynamic properties of the wind turbine system under the operational conditions. Oxford Elsevier Ltd. 2015 Engineering structures 89 260 272 10.1016/j.engstruct.2014.12.034 2016-02-20 OPUS4-32879 Zeitschriftenartikel Hu, Wei-Hua; Thöns, Sebastian; Rohrmann, Rolf; Said, Samir; Rücker, Werner Vibration-based structural health monitoring of a wind turbine system. Part II: Environmental/operational effects on dynamic properties The second part of these companion papers mainly researches environmental/operational influences on structural dynamic properties under normal operational conditions during two years, in order to extract a statistical based damage-sensitive indicator for health monitoring of a wind turbine system. The correlation analyses between experimental identified frequencies, damping values as well as mode shapes and environmental/operational factors such as rotation speed of blades, wind speed, pitch angle, temperature and nacelle direction are presented. It is observed that the frequency estimates are influenced by the nacelle position, the activation of rotor, the rotation speed of blades and the wind speed as well as the temperature. Regarding to the damping estimates, they are mainly associated with variation of the aerodynamic damping due to the increasing wind speed. Besides, the resonance phenomenon is also observed in higher modes. The harmonic frequencies due to blades passing by tower are found and the corresponding damping value decreases. Moreover, the mode shapes in some modes are strongly affected by the position of the nacelle. Subsequently, two types of simulated damage including the reduction of stiffness in both the rotor blade and the tubular tower are successfully detected by applying the Principal Component Analysis (PCA) based methods to these temperature-sensitive frequency estimates. Comparison of change of the extracted health features indicates that they are more sensitive with the tower damage. Oxford Elsevier Ltd. 2015 Engineering structures 89 273 290 10.1016/j.engstruct.2014.12.035 2016-02-20 OPUS4-44535 Beitrag zu einem Tagungsband Berchtold, Florian; Knaust, Christian; Rogge, Andreas; Arnold, L.; Thöns, Sebastian Lönnermark, Anders; Ingason, Haukur Risk Analysis for Road Tunnels - A Metamodel to Efficiently Integrate Complex Fire Scenarios Fires in road tunnels constitute complex scenarios with interactions between the fire, tunnel users and safety measures. More and more methodologies for risk analysis quantify the consequences of these scenarios with complex models. Examples for complex models are the computational fluid dynamics model Fire Dynamics Simulator (FDS) and the microscopic evacuation model FDS+Evac. However, the high computational effort of complex models often limits the number of scenarios in practice. To balance this drawback, the scenarios are often simplified. Accordingly, there is a challenge to consider complex scenarios in risk analysis. To face this challenge, we improved the metamodel used in the methodology for risk analysis presented on ISTSS 2016. In general, a metamodel quickly interpolates the consequences of few scenarios simulated with the complex models to a large number of arbitrary scenarios used in risk analysis. Now, our metamodel consists of the projection array-based design, the moving least squares method, and the prediction interval to quantify the metamodel uncertainty. Additionally, we adapted the projection array-based design in two ways: the focus of the sequential refinement on regions with high metamodel uncertainties; and the combination of two experimental designs for FDS and FDS+Evac. To scrutinise the metamodel, we analysed the effects of three sequential refinement steps on the metamodel itself and on the results of risk analysis. We observed convergence in both after the second step (ten scenarios in FDS, 192 scenarios in FDS+Evac). In comparison to ISTSS 2016, we then ran 20 scenarios in FDS and 800 scenarios in FDS+Evac. Thus, we reduced the number of scenarios remarkably with the improved metamodel. In conclusion, we can now efficiently integrate complex scenarios in risk analysis. We further emphasise that the metamodel is broadly applicable on various experimental or modelling issues in fire safety engineering. RISE Safety 2018 Proceedings from the Eighth International Symposium on Tunnel Safety and Security 8 978-91-88695-48-2 International Symposium on Tunnel Safety and Security Boras, Sweden 14.03.2018 16.03.2018 349 360 2018-03-21 OPUS4-44537 Zeitschriftenartikel Thöns, Sebastian On the Value of Monitoring Information for the Structural Integrity and Risk Management This article introduces an approach and framework for the quantification of the value of structural health monitoring (SHM) in the context of the structural risk and integrity management for systems. The quantification of the value of SHM builds upon the Bayesian decision and utility theory, which facilitates the assessment of the value of information associated with SHM. The principal approach for the quantification of the value of SHM is formulated by modeling the fundamental decision of performing SHM or not in conjunction with their expected utilities. The expected utilities are calculated accounting for the probabilistic performance of a system in conjunction with the associated structural integrity and risk management actions throughout the life cycle, the associated benefits, structural risks, and costs and when performing SHM, the SHM information, their probabilistic outcomes, and costs. The calculation of the expected utilities necessitates a comprehensive and rigorous modeling, which is introduced close to the original formulations and for which analysis characteristics and simplifications are described and derived. The framework provides the basis for the optimization of the structural risk and integrity management based on utility gains including or excluding SHM and inspection information. Studies of fatigue deteriorating structural Systems and their characteristics (1) provide decision Support for the performance of SHM, (2) explicate the influence of the structural component and system characteristics on the value of SHM, and (3) demonstrate how an integral optimization of SHM and inspection strategies for an efficient structural risk and integrity management can be performed. Hoboken, NJ, USA John Wiley & Sons, Inc. 2018 Computer-Aided Civil and Infrastructure Engineering 33 1 79 94 10.1111/mice.12332 2018-03-21 OPUS4-50808 Zeitschriftenartikel Long, Lijia; Döhler, M.; Thöns, Sebastian Determination of structural and damage detection system influencing parameters on the value of information A method to determine the influencing parameters of a structural and damage detection system is proposed based on the value of Information analysis. The value of information analysis utilizes the Bayesian pre-posterior decision theory to quantify the value of damage detection system for the structural integrity management during service life. First, the influencing parameters of the structural system, such as deterioration type and rate are introduced for the performance of the prior probabilistic system model. Then the influencing parameters on the damage detection system performance, including number of sensors, sensor locations, measurement noise, and the Type-I error are investigated. The preposterior probabilistic model is computed utilizing the Bayes' theorem to update the prior system model with the damage indication information. Finally, the value of damage detection system is quantified as the difference between the maximum utility obtained in pre-posterior and prior analysis based on the decision tree analysis, comprising structural probabilistic models, consequences, as well as benefit and costs analysis associated with and without monitoring. With the developed approach, a case study on a statically determinate Pratt truss bridge girder is carried out to validate the method. The analysis shows that the deterioration rate is the most sensitive parameter on the effect of relative value of information over the whole service life. Furthermore, it shows that more sensors do not necessarily lead to a higher relative value of information; only specific sensor locations near the highest utilized components lead to a high relative value of information; measurement noise and the Type-I error should be controlled and be as small as possible. An optimal sensor employment with highest relative value of information is found. Moreover, it is found that the proposed method can be a powerful tool to develop optimal service life maintenance strategies—before implementation—for similar bridges and to optimize the damage detection system settings and sensor configuration for minimum expected Costs and risks. Thousand Oaks, Calif. Sage Publications 2022 Structural health monitoring 21 1 19 36 urn:nbn:de:kobv:b43-508083 10.1177/1475921719900918 https://creativecommons.org/licenses/by-nc/4.0/deed.de 2020-05-25 OPUS4-50809 Beitrag zu einem Tagungsband Bayane, I.; Long, Lijia; Thöns, Sebastian; Brühwiler, E. Quantification of the conditional value of SHM data for the fatigue safety evaluation of a road viaduct Fatigue safety verification of existing bridges that uses ''re-calculation'' based on codes, usually results in insufficient fatigue safety, triggering invasive interventions. Instead of "re-calculation", Structural Health Monitoring (SHM) should be used for the assessment of the existing bridges. Monitoring systems provide data that can reduce uncertainties associated with the fatigue loading process and the structural resistance. The objective of this paper is to quantify the value of the SHM system implemented in a 60-years-old road viaduct to investigate its fatigue safety, through modeling of the fundamental decisions of performing monitoring in conjunction with its expected utility. The quantification of the conditional value of information is based on the decision tree analysis that considers the structural reliability, various decision scenarios as well as the cost-benefit assessments. This leads to a quantitative decision basis for the owner about how much time and money can be saved while the viaduct fulfills its function reliably and respects the safety requirements. The originality of this paper stands in the application of the value of information theory to an existing viaduct considering the fatigue failure of the system based on the monitoring data and the cost-benefit of monitoring method. Seoul, South Korea 2019 13th International Conference on Applications of Statistics and Probability in Civil Engineering Seoul, South Korea 26.05.2019 30.05.2019 275 288 2020-05-25 OPUS4-50794 Zeitschriftenartikel Thöns, Sebastian; Stewart, M. G. On the cost-efficiency, significance and effectiveness of terrorism risk reduction strategies for buildings We analyse the performance of risk reduction strategies for Terrorist attacks with Improvised Explosive Devices (IEDs) for large governmental building structures in terms of cost-efficiency, significance and effectiveness Accounting for life safety in conjunction with societal preferences and capabilities. The approach builds upon an extended Bayesian pre-posterior decision analysis and the principles of the marginal lifesaving costs based on the Life Quality Index (LQI). The decision scenario is formulated for a decision maker responsible for the safety of governmental or large commercial buildings and consequently the direct risks, the indirect risks due to fatalities and economical importance of the building beside the expected cost for the individual risk reduction strategies are modelled, aggregated and optimised. The considered risk reduction strategies encompass an explicit consideration and distinction of information and actions such as (i) threat surveillance may trigger the temporary evacuation of the building, (ii) the implementation of protection provisions provided by codes and guidelines, (iii) a detailed progressive collapse assessment and specific protection measures and (iv) the combination of protection and surveillance. All considered strategies are found to contribute to risk reduction and can be costefficient, especially for higher threat probabilities. The risk reduction strategies comply with societal macroeconomic and demographical characteristics and societal preferences according to the LQI. The progressive collapse assessment with targeted protection measures is found to be the most cost-efficient, significant and effective counter-terrorism strategy. This finding points to the necessity for a comprehensive utilisation of scientific methods and sophisticated engineering for progressive collapse assessment to determine targeted protection measures. Elsevier Ltd. 2020 Structural Safety 85 10195 10.1016/j.strusafe.2020.101957 2020-05-20 OPUS4-51409 Zeitschriftenartikel Long, Lijia; Anh Mai, Q.; Morato, P. G.; Dalsgaard Sorensen, J.; Thöns, Sebastian Information value-based optimization of structural and environmental monitoring for offshore wind turbines support structures The use of load and structural performance measurement information is vital for efficient structural integrity management and for the cost of energy production with Offshore Wind Turbines (OWTs). OWTs are dynamically sensitive structures subject to an interaction with a control unit exposed to repeated cyclic wind and wave loads causing deterioration and fatigue. This study focuses on the quantification of the value of structural and environmental information on the integrity management of OWT structures, with the focus on fatigue of welded joints. By utilizing decision analysis, structural reliability methods, measurement data, as well as the cost-benefit models, a Value of Information (VoI) analysis can be performed to quantify the most beneficial measurement strategy. The VoI assessment is demonstrated for the integrity management of a butt welded joint of a monopile support structure for a 3 MW OWT with a hub height of approximately 71m. The conditional value of three-year measured oceanographic information and one-year strain monitoring information is quantified posteriori in conjunction with an inspection and repair planning. This paper provides insights on how much benefits can be achieved through structural and environmental information, with practical relevance on reliability-based maintenance of OWT structures. Elsevier Ltd. 2020 Renewable Energy 10 159 1036 1046 urn:nbn:de:kobv:b43-514098 10.1016/j.renene.2020.06.038 https://creativecommons.org/licenses/by/4.0/deed.de 2020-10-12 OPUS4-32970 Beitrag zu einem Tagungsband Hu, Wei-Hua; Thöns, Sebastian; Said, Samir; Rücker, Werner Cunha, A.; Caetano, E.; Ribeiro, P.; Müller, G. Resonance phenomenon in a wind turbine system under operational conditions A prototype of wind turbines in 5 megawatt dass was built and tested at the first German offshore wind energy test fteld in the North Sea. In order to investigate dynamic behaviors under a complex state of loads, a continuous dynamic monitoring System was implemented by Federal Institute for Material Research and Testing (BAM). It recorded structural responses and environmental/operational variables from November 2007 to October 2009. This paper presents significant resonance phenomenon due to the interaction in the tower-nacelle System under operational conditions. Modal parameters are automatically estimated by the poly reference Least Square Complex Frequency domain (p-LSCF) method. Campbell plot demonstrates that a three-blade passage frequency and its multiples f3n match with the natural frequencies of the wind turbine System in several modal Orders. The damping estimates decrease and the Vibration amplitude increase significantly. A control System is necessary to minimize the excessive vibrations. 2014 EURODYN 2014 - 9th International conference on structural dynamics (Proceedings) 978-972-752-165-4 EURODYN 2014 - 9th International conference on structural dynamics Porto, Portugal 30.06.2014 02.07.2014 3619 3626 2016-02-20 OPUS4-49174 Beitrag zu einem Tagungsband Long, Lijia; Alcover, I. F.; Thöns, Sebastian Quantification of the posterior utilities of SHM campaigns on an orthotropic steel bridge deck This paper contains a quantification and decision theoretical optimization of the posterior utilities for several options for monitoring campaigns on the particular case of fatigue life predictions of an orthotropic steel deck. The monitoring campaigns are defined by varying monitoring durations and phases. The decision analysis is performed with real data from the Structural Health Monitoring (SHM) of the Great Belt Bridge (Denmark) which, among others, consist of measured strains, pavement temperatures and traffic intensities. The fatigue loading prediction model is based on regression models linking daily averaged pavement temperatures, daily aggregated heavy-traffic Counts and derived S-N fatigue damages, all of them derived from the outcomes of different monitoring campaigns. A probabilistic methodology is utilized to calculate the fatigue reliability profiles of selected instrumented welded joints. The posterior utilities of SHM campaigns are then quantified by considering the structural fatigue reliability, various monitoring campaigns and the corresponding cost-benefit models. The decisions of identifying the optimal monitoring campaign and of extending the service life or not in conjunction with monitoring results are modelled. The optimal monitoring campaign is identified - retrospectively - by maximizing the expected benefits and minimize risks in dependency of the monitoring duration and the monitoring associated costs. The results, despite relying on a number of simplistic assumptions, pave the way towards the use of pre-posterior decision support to optimise the design of monitoring campaigns for similar bridges, with an overall goal to proof the cost efficiency of SHM approaches to civil infrastructure management. 2019 IWSHM 2019, The 12th International Workshop on Structural Health Monitoring The 12th International Workshop on Structural Health Monitoring Stanford University, CA, USA 10.09.2019 12.09.2019 265 274 2019-10-07 OPUS4-48481 Beitrag zu einem Tagungsband Long, Lijia; Alcover, I. F.; Thöns, Sebastian Quantification of the posterior utilities of SHM campaigns on an orthotropic steel bridge deck This paper contains a quantification and decision theoretical optimization of the posterior utilities for several options for monitoring campaigns on the particular case of fatigue life predictions of an orthotropic steel deck. The monitoring campaigns are defined by varying monitoring durations and phases. The decision analysis is performed with real data from the Structural Health Monitoring (SHM) of the Great Belt Bridge (Denmark) which, among others, consist of measured strains, pavement temperatures and traffic intensities. The fatigue loading prediction model is based on regression models linking daily averaged pavement temperatures, daily aggregated heavy-traffic Counts and derived S-N fatigue damages, all of them derived from the outcomes of different monitoring campaigns. A probabilistic methodology is utilized to calculate the fatigue reliability profiles of selected instrumented welded joints. The posterior utilities of SHM campaigns are then quantified by considering the structural fatigue reliability, various monitoring campaigns and the corresponding cost-benefit models. The decisions of identifying the optimal monitoring campaign and of extending the service life or not in conjunction with monitoring results are modelled. The optimal monitoring campaign is identified - retrospectively - by maximizing the expected benefits and minimize risks in dependency of the monitoring duration and the monitoring associated costs. The results, despite relying on a number of simplistic assumptions, pave the way towards the use of pre-posterior decision support to optimise the design of monitoring campaigns for similar bridges, with an overall goal to proof the cost efficiency of SHM approaches to civil infrastructure management. 2019 Proceedings of Structural Health Monitoring 2019 IWSHM 2019, The 12th International Workshop on Structural Health Monitoring, Stanford, California, USA Stanford, California, USA 10.09.2019 1 9 2019-07-17 OPUS4-48804 Zeitschriftenartikel Brüske, H.; Thöns, Sebastian Value of pre-construction proof loading information for structural design We introduce a new concept that enables a decision analyst to explore and quantify the benefits of decision alternatives that exceed the scope of a pre-posterior decision or value of information analysis. This new concept, namely, the expected value of sample information and action analysis, facilitates to examine decision alternatives that become only possible with additional knowledge. The concept is introduced by taking basis in proof load testing as a source of (pre-)posterior knowledge. Pre-posterior decision analysis is necessary in order to optimize the structural design through proof loading information. The application of the common value of information Analysis and the new value of information and action analysis are demonstrated in a case study. John Wiley & Sons 2019 Wind Energy 1 17 10.1002/we.2398 2019-09-02 OPUS4-48780 Zeitschriftenartikel Rastayesh, S.; Long, Lijia; Sørensen, J. D.; Thöns, Sebastian Risk Assessment and Value of Action Analysis for Icing Conditions of Wind Turbines Close to Highways The paper presents research results from the Marie Skłodowska-Curie Innovative Training Network INFRASTAR in the field of reliability approaches for decision-making for wind turbines and bridges. This paper addresses the application of Bayesian decision analysis for installation of heating systems in wind turbine blades in cases where an ice detection system is already installed in order to allow wind turbines to be placed close to highways. Generally, application of ice detection and heating systems for wind turbines is very relevant in cases where the wind turbines are planned to be placed close to urban areas and highways, where risks need to be considered due to icing events, which may lead to consequences including human fatality, functional disruptions, and/or economic losses. The risk of people being killed in a car passing on highways near a wind turbine due to blades parts or ice pieces being thrown away in cases of overicing is considered in this paper. The probability of being killed per kilometer and per year is considered for three cases: blade parts thrown away as a result of a partial or total failure of a blade, ice thrown away in two cases, i.e., of stopped wind turbines and of wind turbines in operation. Risks due to blade parts being thrown away cannot be avoided, since low strengths of material, maintenance or manufacturing errors, mechanical or electrical failures may result in failure of a blade or blade part. The blade (parts) thrown away from wind turbines in operation imply possible consequences/fatalities for people near the wind turbines, including in areas close to highways. Similar consequences are relevant for ice being thrown away from wind turbine blades during icing situations. In this paper, we examine the question as to whether it is valuable to put a heating System on the blades in addition to ice detection systems. This is especially interesting in countries with limited space for placing wind turbines; in addition, it is considered if higher power production can be obtained due to less downtime if a heating system is installed. MDPI 2019 Energies 12 14 2653-1 2653-15 urn:nbn:de:kobv:b43-487805 10.3390/en12142653 https://creativecommons.org/licenses/by/4.0/deed.de 2019-08-29 OPUS4-43624 Beitrag zu einem Tagungsband Long, Lijia; Thöns, Sebastian; Döhler, M. Damage Detection and Deteriorating Structural Systems This paper addresses the quantification of the value of damage detection system and algorithm information on the basis of Value of Information (VoI) analysis to enhance the benefit of damage detection information by providing the basis for its optimization before it is performed and implemented. The approach of the quantification the value of damage detection information builds upon the Bayesian decision theory facilitating the utilization of damage detection performance models, which describe the information and its precision on structural system level, facilitating actions to ensure the structural integrity and facilitating to describe the structural system performance and its functionality throughout the service life. The structural system performance is described with its functionality, its deterioration and its behavior under extreme loading. The structural system reliability given the damage detection information is determined utilizing Bayesian updating. The damage detection performance is described with the probability of indication for different component and system damage states taking into account type 1 and type 2 errors. The value of damage detection information is then calculated as the difference between the expected benefits and risks utilizing the damage detection information or not. With an application example of the developed approach based on a deteriorating Pratt truss system, the value of damage detection information is determined,demonstrating the potential of risk reduction and expected cost reduction. 2017 Proceedings of the 11th International Workshop on Structural Health Monitoring 978-1-60595-330-4 International Workshop on Structural Health Monitoring Stanford, CA, USA 12.09.2017 14.09.2017 1276 1284 2018-01-08 OPUS4-46964 Zeitschriftenartikel Thöns, Sebastian; Döhler, M.; Long, Lijia On Damage Detection System Information for Structural Systems Damage detection systems (DDS) provide information of the structural system integrity in contrast to e.g. local information by inspections or non-destructive testing techniques. In this paper, an approach is developed and demonstrated to utilize DDS information to update the structural system reliability and to integrate this information in structural system risk and utility analyses. For this aim, a novel performance modelling of DDS building upon their system characteristics and non-destructive testing reliability is introduced. The DDS performance modelling accounts for a measurement system in combination with a damage detection algorithm attached to a structural system in the reference and damage states and is modelled with the probability of indication accounting for type I and II errors. In this way, the basis for DDS performance comparison and assessment is provided accounting for the dependencies between the damage states in a structure. For updating of the structural system reliability, an approach is developed based on Bayesian updating facilitating the use of DDS information on structural system level and thus for a structural system risk analysis. The structural system risk analysis encompasses the static, dynamic, deterioration, reliability and consequence models, which provide the basis for the system model for calculating the direct risks due to component failure and the indirect risks due to system failure. Two case studies with the developed approach demonstrate a high Value of DDS Information due to risk and expected cost reduction. Taylor & Francis 2018 Structural Engineering international 28 3 255 268 10.1080/10168664.2018.1459222 2018-12-12 OPUS4-41344 Beitrag zu einem Tagungsband Schneider, Ronald; Thöns, Sebastian; Rogge, Andreas Bucher, Christian; Ellingwood, Bruce R.; Frangopol, Dan M. Simulating the service life performance of an inspected group of jacket-type structures A novel method for risk-based optimization of inspection and repair strategies for deteriorating structural systems has recently been proposed. The method defines heuristics at the system level to reduce the number of possible strategies. For each defined strategy, it computes the updated system failure probability conditional on simulated inspection and repair histories, and evaluates the associated costs and risk. The expected total service life costs and risk for a strategy are finally determined using Monte Carlo simulation. The optimal strategy minimizes the expected total service life costs and risk. We intend to adopt this approach to optimize inspection, monitoring and repair activities for offshore wind park support structures. As a first step, we simulate - in analogy to an offshore wind park - the service life performance of an inspected group of jacket-type frames. The performance is quantified in terms of the group's system failure probability conditional on simulated inspection and repair histories. The underlying system model accounts for the structural redundancy of the frames and the interdependence among their failure events due to similar loading conditions. The model also captures stochastic dependence among the deterioration states of the frames. As part of the simulation process the a-priori unknown outcome of any planned inspection is generated conditional on the outcome of all previous inspections. Vienna, Austria TU-MV Media Verlag GmbH 2017 Proceedings of the 12th International Conference on Structural Safety and Reliability 978-3-903024-28-1 12th International Conference on Structural Safety and Reliability Vienna, Austria 06.08.2017 10.08.2017 2738 2747 2017-08-15 OPUS4-46190 Beitrag zu einem Tagungsband Long, Lijia; Thöns, Sebastian; Döhler, M. The effects of SHM system parameters on the value of damage detection information This paper addresses how the value of damage detection Information depends on key Parameters of the Structural Health Monitoring (SHM) system including number of sensors and sensor locations. The Damage Detection System (DDS) provides the information by comparing ambient vibration measurements of a (healthy) reference state with measurements of the current structural system. The performance of DDS method depends on the physical measurement properties such as the number of sensors, sensor positions, measuring length and sensor type, measurement noise, ambient excitation and sampling frequency, as well as on the data processing algorithm including the chosen type I error for the indication threshold. The quantification of the value of Information (VoI) is an expected utility based Bayesian decision analysis method for quantifying the difference of the expected economic benefits with and without information. The (pre-)posterior probability is computed utilizing the Bayesian updating theorem for all possible indications. If changing any key parameters of DDS, the updated probability of system failure given damage detection information will be varied due to different indication of probability of damage, which will result in changes of value of damage detection information. The DDS system is applied in a statically determinate Pratt truss bridge girder. Through the analysis of the value of information with different SHM system characteristics, the settings of DDS can be optimized for minimum expected costs and risks before implementation. 2018 9th European Workshop on Structural Health Monitoring 9th European Workshop on Structural Health Monitoring Manchester, UK 10.07.2018 375 384 2018-10-09 OPUS4-57879 Beitrag zu einem Tagungsband Kapoor, M.; Sørensen, J. D.; Ghosh, S.; Thöns, Sebastian Decision theoretic approach for identification of optimal proof load with sparse resistance information Proof load testing may be performed to confirm the reliability of the bridge for an existing classification or to prove the reliability for a higher classification. In this paper, a probabilistic decision analysis approach is applied to the scenario for the evaluation of target proof load in the situation where information on the bridge resistance model is lacking. In this case, the resistance model is established by proof loading and taking very basic prior knowledge into account. The decision scenario is modelled in the context of the proof load test planner who shall choose the required load level for assessment of a bridge. The choice of the load level depends on the risks due to the testing and the expected benefit gain from the test. Information acquired about the loading response from monitoring during the proof load testing is modelled by taking basis in the model uncertainty formulation. The optimal proof load level for classification of a single lane, simply supported bridge of 8m span subjected to live load from very heavy (gross weight > 80 tons) transport vehicles was calculated. The optimal proof load level was identified as leading to a positive expected benefit gain to the decision maker while also satisfying target reliability criteria for remaining service life. The analysis was performed for the evaluation of bridge performance with respect to five classifications of very heavy transport vehicles with different vehicle weights and configurations. Boca Raton, Florida CRC Press 2021 Proceedings of the 10th international conference on bridge maintenance, safety and management (IABMAS) 978-0-429-27911-9 10th International Conference on Bridge Maintenance, Safety and Management (IABMAS) Sapporo, Japan 11.04.2021 15.04.2021 789 797 10.1201/9780429279119-104 2023-07-07