Typological classification of existing bridge piers interacting with river flow: the case study of bridges in the Matera provincial road network

Bridge piers are critical structural elements whose interaction with river flow may significantly influence hydraulic behavior and structural integrity. This is due to the fact that piers geometry and their alignment can induce flow deviation, turbulence, and general or local scour. This paper presents the first results of statistical typological study conducted on bridge piers across Matera province road network (Basilicata, Southern Italy), collected on inspections of a total of 247 bridges. In particular, in this paper piers belonging to a sample of 95 bridges having a Hydraulic Hazard Class varying from High (H) to Medium-Low (ML) are considered, among which 48 of these are affected by scour. The relationship between pier typology and river morphological–hydraulic characteristics is investigated, considering pier shape, foundation type, materials, conservation state, and flow alignment, together with riverbed morphology and hydraulic behavior. The preliminary results show that rectangular piers with rounded corners account for 43.8% of scoured bridge cases, with higher scour susceptibility associated with moderate contraction ratios (10–30%), non-zero flow attack angles, and medium-sized basins. The main findings of this work may be a support for improving the multi-level approach applied within the Italian bridge Guidelines for risk assessment of existing bridges.