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Vibration monitoring of a footbridge with a wireless sensor network

Monitoring the vibration performance of structures for serviceability assessment purposes usually requires a deployment of several weeks or months to collect a dataset allowing a reliable assessment. Since for this type of medium term deployments installation costs are a key factor, wireless monitoring with its fast deployment has an advantage over wired monitoring systems. This paper describes a deployment of a wireless monitoring system on a timber footbridge. The goal of the monitoring was to provide information about vibration amplitudes during operation and to track changes of relevant natural frequencies with the temperature. Accelerations were permanently recorded and the acquired data was processed in the nodes to compute the envelope of the vibration amplitude and the dominant peaks of the Fourier spectrum. The wireless monitoring system that was deployed for one year provided accurate data matching the requirements of vibration performance assessments. The deployment demonstrated that a wireless sensor network is a technically feasible and economically effective mean to monitor the vibration performance of a structure.