Modal Data Identification of the Prestressed Concrete Bridge Using Variational Mode Decomposition (original) (raw)
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Proceedings of the New Zealand Society for Earthquake Engineering Annual Conference 2015, Rotorua, New Zealand, April 10–12, 2015, pp. 1-8, doi: 10.13140/RG.2.1.1647.5680, 2015
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Engineering Structures, 2020
The paper describes and evaluates application of output-only system identification to an eleven-span post-tensioned concrete bridge using hybrid excitation. A linear chirp sweeping force, induced by two lightweight electro-dynamic shakers, augmented environmental sources to excite the bridge during the hybrid testing exercise. To obtain the modal characteristics of the structure, two output-only time domain system identification methods were employed, namely auto-regressive (AR) time series model and eigensystem realization algorithm with observer/Kalman identification (ERA-OKID), with the traditional data-driven stochastic subspace identification method (SSI-data) providing a comparative benchmark. The accuracy and efficiency of both system identification algorithms when used on hybrid testing data are investigated and compared to the results from purely ambient vibration testing data. The study demonstrates that using both output-only identification algorithms the collected vibration responses induced by the proposed hybrid vibration testing methodology can be used for extracting modal parameters with enhanced accuracy and reliability (i.e. more identified modes) for the large-scale post-tensioned concrete bridge due to the increase in the excitation strength and better coverage of the relevant frequency bands. Compared to the classical SSI-data, the AR and ERA-OKID techniques were able to identify more modes at reduced computational cost when applied to voluminous data from multi-channel measurements.
Infrastructures
The paper is part of a case study concerning the structural assessment of a historical infrastructure in the local territory, a road three-span reinforced concrete arch bridge over a river, built by the end of World War I (1917). The purpose of the paper is twofold: first, in-situ acquired response data are systematically analysed by specific signal processing techniques, to form a devoted methodological procedure and to extract useful information toward possible interpretation of the current structural conditions; second, the deciphered information is elaborated, in view of obtaining peculiar conceptualisations of detailed features of the structural response, as meant to achieve quantitative descriptions and modelling, for final Structural Health Monitoring (SHM) and intervention purposes. The proposed methodology, integrating self-implemented and adapted classical signal processing methods, and refined techniques, such as Wavelet analysis and ARMA models, assembles a rather genera...
Post-Processing Ambient and Forced Response Bridge Data to Obtain Modal Parameters
2001
In this paper, post-processing methods were applied to three different sets of multiple channel time domain vibration response data taken from the Z24 highway bridge in Switzerland. The objective of this exercise was to compare the mode shapes resulting from each of these data sets with one another. Ideally, all of the tests should yield the same mode shapes, although perhaps not all modes would be excited in each case. The three different test cases were; Case 1: Two shaker response data, including the simultaneously measured excitation forces. The shakers were driven by uncorrelated random signals. Case 2: Impact response data, including three reference responses but no measured forces. The impact force was provided by a 100 kg. drop weight impactor. Case 3: Ambient response data, including three reference (fixed) responses. Excitation was provided by automobile traffic on an adjoining bridge. Excitation forces were measured in Case 1, so multiple reference Frequency Response Func...