Maximum likelihood identification of non-stationary operational data

Parloo, Eli; Guillaume, Patrick; Cauberghe, Bart

doi:10.1016/s0022-460x(03)00377-8

Cited by 38 publications

(25 citation statements)

References 13 publications

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“…Furthermore, in such structures, ambient excitation sourcesfor instance from wind -are always present in addition to the controlled input forces, thereby compromising the input-output relationship (Parloo et al, 2003).…”

Section: Forced Vibration Testsmentioning

confidence: 99%

In Situ Dynamic Characteristics of Reinforced Concrete Shear Wall Buildings

Gilles

McClure

2012

Structures Congress 2012

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Structural engineers routinely need to make assumptions about the dynamic properties (natural periods, mode shapes, and damping) of a building to simulate its response to dynamic loads, such as strong winds or earthquake ground motions. However, the assumed properties may significantly differ from those of the actual building, once it is constructed, due to differences between the idealized model and in situ conditions. The main objectives of this study are to evaluate how common models and assumptions used to predict the dynamic properties of buildings compare to those measured in actual buildings, and to develop improved prediction models.To this end, ambient vibration measurements were performed in 39 buildings on the island of Montréal and the dynamic properties of up to six vibration modes were identified, for each of these buildings, using the enhanced frequency domain decomposition method. Though the initial goal was to obtain a representative sample of different types of buildings, 27 of these 39 buildings turned out to be reinforced concrete buildings with shear walls providing the main resistance to lateral loads. Hence, the scope of this study was narrowed to the dynamic properties of reinforced concrete shear wall (RCSW) buildings. The measured dynamic properties of this subset of 27 buildings were then used to evaluate different models, proposed in building codes and in the literature, to predict the natural periods and damping characteristics of these types of buildings. Finally, simple models to predict the natural periods of torsion and second translation modes were proposed based on regression analyses. These models agree very well with those that have been proposed in the literature. Again, equations corresponding to different probability levels (mean, mean minus one standard deviation, and mean plus one standard deviation) were produced as a measure of uncertainty.This study should help engineers select realistic values of the dynamic properties of RCSW buildings for structural analysis and design, and should ultimately improve engineers' ability to predict the dynamic response of these buildings. Further, the proposed models could lead to improved recommendations in building codes.iii This research could not have been possible without the help of many building owners and managers, who allowed our team to perform vibration measurements in their buildings. I would also like to thank the numerous graduate and undergraduate students who were involved in these tests for both their participation and the stimulating discussions that often ensued:

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Section: Forced Vibration Testsmentioning

confidence: 99%

In Situ Dynamic Characteristics of Reinforced Concrete Shear Wall Buildings

Gilles

McClure

2012

Structures Congress 2012

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“…Because the acquisition is done using the SLDV, an accelerometer was mounted on the ceiling as a reference. This reference measurement is necessary for the OMA approach to obtain useful phase information and to cope with the non-stationarity of the ambient excitation (see [16]). …”

Section: Note That a Large 2 Kn Shaker Could Be Used To Apply Arbitramentioning

confidence: 99%

Implementation of the Scanning Laser Doppler Vibrometer Combined with a Light-Weight Pneumatic Artificial Muscle Actuator for the Modal Analysis of a Civil Structure

Deckers

Guillaume

Vuye

et al. 2012

Shock and Vibration

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Abstract. The identification of the modal parameters of bridges and other large civil constructions has become an important research issue. Different approaches have been proposed depending on the excitation used: ambient excitations (due to wind, traffic, . . .) or artificial excitations (e.g. impact test with heavy drop weights). In practice it turns out that not all modes are well excited by the ambient forces. Hence the application of an artificial actuator is advisable. The problem is that larger constructions often require large and heavy excitation devices, which are hard to manipulate. Another difficulty encountered in performing a modal analysis on large civil constructions is the necessity for a large number of high sensitivity sensors. Consequently a large number of cables has to be installed resulting in a large setup time.This paper is a proof-of-concept which demonstrates the possibility of using lightweight Pneumatic Artificial Muscles combined with the scanning laser Doppler vibrometer to perform a modal analysis on a civil structure. This combination allows for an important reduction in setup time and allows for sine testing as well as the application of broadband signals such as periodic chirps, true noise or multisines.

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“…As a result, the estimated mode shape vectors remain unscaled (i.e. dependent on the unknown level of ambient excitation) [15]. The relationship between the unscaled mode shape vector c f g i (as obtained by in-operation modal analysis) and the corresponding correctly scaled mode shape vector f f g i (as can be obtained from a classical forced-vibration test) of mode i can, therefore, be expressed by…”

Section: Sensitivity-based Rescaling Of Operational Mode Shapesmentioning

confidence: 99%

“…It can be stated that, for a given mode, the shift in natural frequency should be at least 10 times larger than the uncertainty (99.8% confidence interval) estimated for that shift. All these uncertainties can be directly obtained by making use of an ML estimator [1,15,17]. For some specific applications, the application of the sensitivity-based normalisation technique may not always be straightforward.…”

Section: Sensitivity-based Rescaling Of Operational Mode Shapesmentioning

confidence: 99%

“…If the shifts between one (or more) natural frequencies of the reference and damaged condition are statistically significant, a positive damage detection verdict is obtained. The required 3s confidence intervals can be directly obtained by making use of an ML estimator [1,15,17]. It should be noted that environmental changes (for instance changes in temperature, etc.)…”

Section: Sensitivity-based Damage Identification For Operational Datamentioning

confidence: 99%

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