Modal-based monitoring of a pedestrian bridge for damage detection

A significant percentage of bridge superstructures in Germany are in a critical state of health due to age and damages. Therefore, in recent years, the demand for suitable monitoring systems to detect damage processes at an early stage and to enable more targeted rehabilitation and repair has increased. In this paper, the modal-based monitoring of a pedestrian bridge is presented. The aim is not only to identify damage processes based on the vibration behaviour of bridge structures but also to check the effect of repair and strengthening measures. The influence of damage, the type of sensor, the sampling rate, the signal length and the effects of the repair and strengthening measures were examined. By numerical investigations it can be shown that different damage patterns cause characteristic changes of the modal parameters. Finally, the influence of the refurbishment of the support consoles as well as the strengthening measure by near surface mounted (NSM) carbon fibre reinforced polymer (CFRP) strips on the modal parameters were investigated.