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 T2 - IRIS Industrial safety and life cycle engineering - Technologies / Standards / Applications 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 - Marin, L. A1 - Döhler, Michael A1 - Bernal, D. A1 - Mevel, L. ED - Chang, F.-K. T1 - Statistical based decision making for damage localization with influence lines T2 - IWSHM 2013 - 9th International workshop on structural health monitoring (Proceedings) N2 - A theorem on damage localization from flexibility changes has been proven recently, where it has been shown that the image of the change in flexibility δF between damaged and reference states of a structure is a basis for the influence lines of stress resultants at the damaged locations. This damage localization approach can operate on output-only vibration measurements from damaged and reference states, and a finite element model of the structure in reference state is required. While the localization approach is based on purely mechanical principles, an estimate of the image of δF is required from the data that is subject to statistical uncertainty due to unknown noise excitation and finite data length. In this paper, this uncertainty is quantified from the measurements and a statistical framework is added for the decision about damaged elements. The combined approach is successfully applied to a numerical simulation and to a cantilever beam in a lab experiment. T2 - IWSHM 2013 - 9th International workshop on structural health monitoring CY - Stanford, CA, USA DA - 2013-09-10 PY - 2013 SN - 978-1-60595-115-7 VL - 1 SP - 159 EP - 166 AN - OPUS4-30476 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Le Cam, V. A1 - Döhler, Michael A1 - Le Pen, M. A1 - Mevel, L. ED - Chang, F.-K. T1 - Embedded modal analysis algorithms on the smart wireless sensor platform PEGASE T2 - IWSHM 2013 - 9th International workshop on structural health monitoring (Proceedings) N2 - Operational modal analysis and vibration based damage detection of engineering structures have become important issues for Structural Health Monitoring (SHM) and maintenance operations, e.g. on transport infrastructure. Methods from control engineering have been adopted and converted for the application on civil structures. Approaches like subspace-based system identification combine excellent theoretical properties under the unknown excitation properties of a structure with practical usefulness. In this paper, the implementation of covariance-driven stochastic subspace identification (SSI) on the smart wireless sensor platform PEGASE is described. Special care is taken about the fast implementation of this technique since the computations are embedded on the platform and perform in real-time. The most efficient and current version of subspace algorithms has been implemented. Efficiency and memory consumption are primary criteria in this implementation. First validated results will be given for each step of the algorithms: crosscorrelation on natural inputs signal from sensors; Hankel matrix output; SSI implementation using the LAPACK library to get a SVD, pseudo-inverse, eigenvalues etc. Results validation has been correlated between PEGASE implementation and the previous processing in static situation: the same data was collected by wired sensors and data-loggers, then, later, processed on a PC using traditional Matlab software. In parallel, from an engineering point of view, a description of the PEGASE wireless platform will be given: generic usage, wide capacities, embedded Digital Signal Processing (DSP) processor and Library over a small embedded Linux Operating System, a very accurate synchronization principle based on a GPS/PPS principle, etc. Perspectives about a complete technical in-situ installation will also be given. T2 - IWSHM 2013 - 9th International workshop on structural health monitoring CY - Stanford, CA, USA DA - 2013-09-10 PY - 2013 SN - 978-1-60595-115-7 VL - 1 SP - 1210 EP - 1217 AN - OPUS4-30477 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 T2 - IWSHM 2011 - 8th International workshop on structural health monitoring 2011 (Proceedings) 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 T2 - EURODYN 2011 - 8th International conference on structural dynamics (Proceedings) 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 - Döhler, M. A1 - Hille, Falk A1 - Lam, X.-B. A1 - Mevel, L. A1 - Rücker, Werner ED - Proulx, T. T1 - Confidence intervals of modal parameters during progressive damage test T2 - 29th IMAC - Conference on structural dynamics (Proceedings) N2 - In Operational Modal Analysis, the modal parameters (natural frequencies, damping ratios and mode shapes) obtained from Stochastic Subspace Identification (SSI) of a structure, are afflicted with statistical uncertainty. For evaluating the quality of the obtained results it is essential to know the respective confidence intervals of these figures. In this paper we present algorithms that automatically compute the confidence intervals of modal parameters obtained from covarianceand data-driven SSI of a structure based on vibration measurements. They are applied to the monitoring of the modal parameters of a prestressed concrete highway bridge during a progressive damage test that was accomplished within the European research project IRIS. Results of the covariance- and data-driven SSI are compared. T2 - 29th IMAC - Conference on structural dynamics CY - Jacksonville, FL, USA DA - 31.01.2011 KW - Stochastische subspace basierte Identifikation KW - Schadensdetektion KW - Spannbetonbrücke PY - 2011 SN - 978-1-4419-9304-5 DO - https://doi.org/10.1007/978-1-4419-9305-2_17 SN - 2191-5644 N1 - Serientitel: Conference Proceedings of the Society for Experimental Mechanics Series – Series title: Conference Proceedings of the Society for Experimental Mechanics Series VL - 4 SP - 237 EP - 250 PB - Springer AN - OPUS4-24335 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -