Scour-induced dynamic properties modification of masonry arch bridges with different geometry

This paper, focused on the effect of local scour actions on masonry bridges, represents a followup of a previous study conducted by the authors aimed at analysing the effect of a localised scour-induced settlement of the pier on the modal properties of the bridge (i.e., frequencies and mode shapes). Results from the previous study showed as the scour phenomenon, even at its early stages could induced a non-negligible variability of the transverse modal shape of a masonry arch bridge selected as case study. In this paper, the work is continued by analysing how the bridge geometry can affect the aforesaid results. To this aim, bridges with three different geometry (130 m length, 100 m length, 50 m length) are analysed by simulating the scour evolution under the piers and by monitoring the modal response at different stages of the excavation. Accurate finite element models are developed in Abaqus, accounting for both mechanical and geometrical nonlinearities.