Structural identification based on optimally weighted modal residuals

Christodoulou, Konstantinos; Papadimitriou, Costas

doi:10.1016/j.ymssp.2006.05.011

Cited by 78 publications

(78 citation statements)

References 24 publications

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“…In Eq. (1), W is a weighting matrix for modal residuals, a diagonal weighting matrix with each diagonal coefficient assigned based on the estimation uncertainty (coefficient-of-variation) of the natural frequency of the corresponding mode [17] as well as the modal contribution of this mode. Weight factors assigned to mode shape residuals are equal to the weight factor of that…”

Section: Objective Functionmentioning

confidence: 99%

Damage identification study of a seven-story full-scale building slice tested on the UCSD-NEES shake table

He²,

et al. 2010

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A full-scale seven-story reinforced concrete building section was tested on the UCSD-NEES shake table during the period October 2005 -January 2006. The shake table tests were designed to damage the building progressively through four historical earthquake records. At various levels of damage, ambient vibration tests and low amplitude white noise base excitations with root-mean-square accelerations of 0.03g and 0.05g were applied to the building, which responded as a quasi-linear system with parameters evolving as a function of structural damage.Modal parameters (natural frequencies, damping ratios and mode shapes) of the building were identified at different damage levels based on the response of the building to ambient as well as low amplitude white noise base excitations, measured using DC coupled accelerometers. This paper focuses on damage identification of this building based on changes in identified modal parameters. A sensitivity-based finite element model updating strategy is used to detect, localize and quantify damage at each damage state considered. Three sets of damage identification results 1. Corresponding author. Tel.: +1 858-822-4545; fax: +1 858-822-2260. E-mail address: jpconte@ucsd.edu 2 are obtained using modal parameters identified based on ambient, 0.03g, and 0.05g RMS white noise test data, respectively. The damage identification results obtained in all three cases do not exactly coincide, but they are consistent with the concentration of structural damage observed at the bottom two stories of the building. The difference in the identified damage results is mainly due to the significant difference in the identified modal parameters used in the three cases. The assumption of a quasi-linear dynamic system is progressively violated with increasing level of excitation. Therefore, application of nonlinear FE model updating strategies is recommended in future studies to resolve the errors caused by structural response nonlinearity.

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Section: Objective Functionmentioning

confidence: 99%

Damage identification study of a seven-story full-scale building slice tested on the UCSD-NEES shake table

He²,

et al. 2010

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“…(4) with respect to q can readily be carried out numerically using any available gradient-based algorithms for optimizing a nonlinear function of several variables. In the case of multiple local/global optima, a hybrid optimization algorithm (Christodoulou and Papadimitriou 2007) is used that exploits the advantages of random search evolutionary strategies (Beyer 2001) and gradient-based methods. Specifically, an evolution strategy is used to explore the parameter space and detect the neighborhood of the global optimum, avoiding premature convergence to a local optimum.…”

Section: Earthquake-induced Vibrationsmentioning

confidence: 99%

“…Mottershead and Friswell 1993;Bohle and Fritzen 2003;Teughels et al 2003;Lam et al 2004;Christodoulou and Papadimitriou 2007) to estimate structural parameters associated with a finite element model of a structure. This calibration procedure provides useful insight into the range of validity of the modelling assumptions and is used to improve our understanding of the dynamic behaviour of the structure and its components.…”

Section: Introductionmentioning

confidence: 99%

Structural identification of Egnatia Odos bridges based on ambient and earthquake induced vibrations

Ntotsios

Karakostas

Lekidis

et al. 2008

Bull Earthquake Eng

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Abstract:The dynamic characteristics of two representative R/C bridges on Egnatia Odos motorway in Greece are estimated based on low amplitude ambient and earthquake-induced vibrations. The present work outlines the instrumentation details, algorithms for computing modal characteristics (modal frequencies, damping ratios and modeshapes), modal-based finite element model updating methods for estimating structural parameters, and numerical results for the modal and structural dynamic characteristics of the two bridges based on ambient and earthquake induced vibrations. Transverse, bending and longitudinal modes are reliably identified and stiffness-related properties of the piers, deck and elastomeric bearings of the finite element models of the two bridges are estimated. Results provide qualitative and quantitative information on the dynamic behavior of the bridge systems and their components under low-amplitude vibrations. Modeling assumptions are discussed based on the differences in the characteristics identified from ambient and earthquake vibration measurements. The sources of the differences observed between the identified modal and structural characteristics of the bridges and those predicted by finite element models used for design are investigated and properly justified.

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“…This method is referred in this work as the optimally WRs (OWR) method. It is worth pointing out that the logarithmic estimator in (4) has also been shown to arise from a Bayesian statistical identification point of view [23]. The single objective identification method is computationally attractive since conventional minimization algorithms can be applied to solve the problem.…”

Section: Wr Methodsmentioning

confidence: 99%

Variability of updated finite element models and their predictions consistent with vibration measurements

Papadimitriou¹,

Ntotsios²,

Giagopoulos³

et al. 2011

Struct. Control Health Monit.

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Abstract:A case study on a small-scale laboratory vehicle frame is used to investigate the variability of the updated finite element (FE) models that arises from model and measurement errors and demonstrate the effect of this variability on response predictions. Conventional weighted modal residuals and recently introduced multi-objective identification methods for structural model updating are used to provide the entire spectrum of Pareto optimal FE models consistent with the measured modal data. Similarities and differences between the two model updating methods are explored and the advantages of the multi-objective identification methods are emphasized. A significant variability in Pareto optimal models is observed, which is indicative of the uncertainty in the updated FE models. The dependence of the variability of the Pareto models on the information contained in the measured data and the size of model and measurement errors is explored by varying the number of measured modes, number of sensors, FE mesh discretization sizes, and number of model parameters. The effectiveness of the updated Pareto optimal models and their predictive capabilities are assessed. Frequency response functions and fatigue lifetime predictions are used as example of structural performance variables in order to demonstrate the variability in the response predictions that arises from the variability in the Pareto optimal models. A large variability in the response predictions is observed that cannot be ignored in decisions based on updated FE models. The multi-objective optimization method provides the general framework for properly accounting for model uncertainty in model-based response predictions consistent with measured data.

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Structural identification based on optimally weighted modal residuals

Cited by 78 publications

References 24 publications

Damage identification study of a seven-story full-scale building slice tested on the UCSD-NEES shake table

Damage identification study of a seven-story full-scale building slice tested on the UCSD-NEES shake table

Structural identification of Egnatia Odos bridges based on ambient and earthquake induced vibrations

Variability of updated finite element models and their predictions consistent with vibration measurements

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