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Pre- and Post-identification Merging for Multi-Setup OMA with Covariance-Driven SSI

2011; Springer Nature; Linguagem: Inglês

10.1007/978-1-4419-9825-5_7

2191-5652

Michael Döhler, Edwin Reynders, Filipe Magalhães, Laurent Mevel, Guido De Roeck, Álvaro Cunha,

Infrastructure Maintenance and Monitoring

In Operational Modal Analysis (OMA) of large structures we often need to process sensor data from multiple nonsimultaneously recorded measurement setups. These setups share some sensors in common, the so-called reference sensors that are fixed for all the measurements, while the other sensors are moved from one setup to the next. To obtain the modal parameters of the investigated structure, it is necessary to process the data of all the measurement setups and normalize it as the unmeasured background excitation of each setup might be different. For this we compare three different approaches in this paper which differ in the order of the data merging, normalization and system identification step: The classical PoSER (identification-normalization-merging), the PoGER (merging-identification-normalization) and the PreGER (normalization-merging-identification). Special care was taken with the PreGER method and its efficiency has been tested with respect to the two other methods. The system identification is done with the SSI-cov/ref method. We apply these methods to the extraction of the modal parameters (natural frequencies, damping ratios and mode shapes) of the Luiz I arch bridge in Porto, Portugal, compare them and evaluate the different methods.