A validated robust and automatic procedure for vibration analysis of bridge structures using MEMS accelerometers

authored by: Mohammad Omidalizarandi, Ralf Herrmann, Boris Kargoll, Steffen Marx, Jens-André Paffenholz, Ingo Neumann
Abstract: Today, short- and long-term structural health monitoring (SHM) of bridge infrastructures and their safe, reliable and cost-effective maintenance has received considerable attention. From a surveying or civil engineer’s point of view, vibration-based SHM can be conducted by inspecting the changes in the global dynamic behaviour of a structure, such as natural frequencies (i. e. eigenfrequencies), mode shapes (i. e. eigenforms) and modal damping, which are known as modal parameters. This research work aims to propose a robust and automatic vibration analysis procedure that is so-called robust time domain modal parameter identification (RT-MPI) technique. It is novel in the sense of automatic and reliable identification of initial eigenfrequencies even closely spaced ones as well as robustly and accurately estimating the modal parameters of a bridge structure using low numbers of cost-effective micro-electro-mechanical systems (MEMS) accelerometers. To estimate amplitude, frequency, phase shift and damping ratio coefficients, an observation model consisting of: (1) a damped harmonic oscillation model, (2) an autoregressive model of coloured measurement noise and (3) a stochastic model in the form of the heavy-tailed family of scaled t-distributions is employed and jointly adjusted by means of a generalised expectation maximisation algorithm. Multiple MEMS as part of a geo-sensor network were mounted at different positions of a bridge structure which is precalculated by means of a finite element model (FEM) analysis. At the end, the estimated eigenfrequencies and eigenforms are compared and validated by the estimated parameters obtained from acceleration measurements of high-end accelerometers of type PCB ICP quartz, velocity measurements from a geophone and the FEM analysis. Additionally, the estimated eigenfrequencies and modal damping are compared with a well-known covariance driven stochastic subspace identification approach, which reveals the superiority of our proposed approach. We performed an experiment in two case studies with simulated data and real applications of a footbridge structure and a synthetic bridge. The results show that MEMS accelerometers are suitable for detecting all occurring eigenfrequencies depending on a sampling frequency specified. Moreover, the vibration analysis procedure demonstrates that amplitudes can be estimated in submillimetre range accuracy, frequencies with an accuracy better than 0.1 Hz and damping ratio coefficients with an accuracy better than 0.1 and 0.2 % for modal and system damping, respectively.
Organisation(s): Geodetic Institute
Institute of Concrete Construction
External Organisation(s): BAM Federal Institute for Materials Research and Testing
Anhalt University of Applied Sciences
Clausthal University of Technology
Type: Article
Journal: Journal of Applied Geodesy
Volume: 14
Pages: 327–354
No. of pages: 28
ISSN: 1862-9016
Publication date: 26.07.2020
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Engineering (miscellaneous), Earth and Planetary Sciences (miscellaneous), Modelling and Simulation
Electronic version(s): https://doi.org/10.1515/jag-2020-0010 (Access: Closed)
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