Assessment of the information gain of several monitoring techniques for bridge structural examination

The examination of existing civil structures must be differentiated from designing new structures. To have sustainable and circular asset management, the behavior of these existing structures must be better understood to avoid unnecessary maintenance and replacements. Monitoring data collected through bridge load testing, structural health monitoring, and non-destructive tests may provide useful information that could significantly influence their structural-safety evaluations. Nonetheless, these monitoring techniques are often elaborate, and the monitoring costs may not always justify the benefits of the information gained. Additionally, it is challenging to quantify the expected information gain before monitoring, especially when combining several techniques. This paper proposes several definitions and metrics to quantify the information gained from monitoring data to better evaluate the benefits of monitoring techniques. A full-scale bridge case study in Switzerland is used to illustrate the information gain from multiple monitoring techniques. On this structure, static load tests, three years of strain monitoring, weigh-in-motion measurements, and non-destructive tests were performed between 2016 and 2019. The influence on structural-safety examination is evaluated for each combination of monitoring techniques. Results show that each technique provides unique information and the optimal combination depends on the selected definition of information gain. When data from monitoring techniques are combined, significant reserve capacity of the bridge is determined.