Long-term monitoring of a masonry arch bridge to evaluate scour effects

Evaluating the scour effects on masonry arch bridges is of utmost importance to ensure the continued operational safety of those infrastructures. Even if numerical and laboratory studies have demonstrated the possibility of detecting scour-induced effects by measuring the structural response of masonry bridges, there is a lack of longterm monitoring applications on real structures. Within this context, the paper presents selected results obtained during two years of continuous monitoring of a historical masonry arch bridge to evaluate scour-induced effects. Firstly, on-site inspections of the bridge revealed severe foundation erosion and extensive documentary research was carried out to identify the depth of the foundation level. Subsequently, a monitoring system was installed in the bridge, including several MEMS-based tiltmeters, 1 echosounder, 1 hydrometer and 1 weather station. The correlation between measured rotations and environmental parameters is investigated and a linear regression model is used to minimize/remove temperature-induced effects. The residual errors between measured and predicted rotations highlighted the occurrence of various anomalies.