Longtime monitoring with smart sensor networks: The case of the Zwartewaterbrug

Experiences with a longtime monitoring system applied to the Zwartewaterbrug in the Netherlands are described in this paper. The investigated part is a steel tied-arch bridge of 104 meter in length. It was built in 1972 and is exemplary for the numerous aging bridges where real traffic loads exceed the design loads. The investigation focusses on testing the functionality of a prototype monitoring system. The proposed monitoring system is based on distributed vibration measurements and on the analysis of bridge modal parameters. The data acquisition unit consists of three sensor nodes and 12 measurement channels. Special attention is paid to the usability of low cost sensors for long term bridge monitoring. The monitoring system is simple to install, it stays permanently installed and acquires data during bridge operation. Measurement period was between October 2014 and June 2015. Results show that mode shapes and modal frequencies can automatically be identified and tracked while the bridge is in full operation.