Structural assessment of existing bridges by means of territorial scale analyses

In the last few years, the problem of bridge failure has occurred frequently. The collapse of the Morandi Bridge in 2018 and the collapse of the bridge on Magra River in 2020 are just the most recent and catastrophic events that occurred in Italy and highlighted a problem that needs a systematic method to simplify and speed up maintaining and securing infrastructures. The management of existing bridges is a complex problem that must consider the technical aspects and the social and economic ones. Moreover, the number of Italian bridges is currently uncertain, and often the related documentation is incomplete or does not respect the actual structure. Another problem is the plurality of materials, dimensions, construction periods, and structural schemes used. This makes it even more difficult to standardize the procedure. Infrastructure management and maintenance was born as early as 1967, which gives the first rules on inspection times and methods. Finally arriving in 2019 with circular n°7, which reports specific indications for seismic tests of existing bridges. With all these variables, it is challenging to carry out a complete safety assessment for each bridge of the Italian territory. Therefore, a multilevel approach is fundamental, which, for increasing levels of detail, optimizes resources and costs only where necessary. More in-depth analyzes will only have to be carried out on a few bridges. This thesis analyzes this method on several bridges located in the northwest of Italy. The data are analyzed in aggregate to build a general model of this geographical area. The information of the bridges were inserted into QGIS software, and through a spatial analysis, the correlations between degradation and the external environment were searched. Following the legislation, the maps considered were used to identify the attributes of structural-foundational and seismic risk, hydraulic risk, and landslide risk. By adding this data to the structural analysis, it is possible to identify the attention class for each bridge.