Experimental investigation on structural degradation and dynamic characterization of a cycle-pedestrian bridge

In the last century in Italy and, in particular, in Padua, the cycle-pedestrian bridges represented a connective system of the city that assumed a historical and strategic importance. Indeed, the city owes a significant part of its vitality to this type of works. However, some of these constructions are affected by significant material degradation phenomena and by structural issues related to the dynamic interaction between pedestrians and structure (a.k.a. "lock-in"effect). This paper will explore the case of a historic cycle-pedestrian bridge illustrating the construction methods, the realization phases and the maintenance works carried out. The adopted identification techniques are then illustrated with reference to the operational modal analysis (OMA) and the experimental investigations carried out in the static and dynamic field. The tests were conducted with particular reference to the possibilities of improving the dynamic behaviour of the bridge in terms of frequencies on the horizontal plane. The experimental results before and after the introduction of some constraints to the horizontal displacement are then illustrated, as well as the results of a series of non-destructive tests on some significant points of the structural elements. The work closes by examining possible future structural solutions and related monitoring systems.