Structural Assessment of a Masonry Arch Bridge before and after a traditional inner arch retrofitting technique

To assess the structural behaviour of masonry arch bridge and identify the occurrence of damage reliable numerical models to perform accurate nonlinear structural analyses are needed. The innovative strategy known as Discrete Macro-Element Model (DMEM) is here employed to simulate the performance of a masonry arch bridge before and after a traditional structural retrofitting. The adopted numerical strategy assures a geometrically consistent model characterized by a very low computational burden and reliable results. As case study, a masonry arch bridge located in Maletto (Italy), belonging to the rail network, around Etna volcano, called Ferrovia CircumEtnea (FCE). The bridge has been built in 19th century and was subjected to a structural retrofitting in 1984, because of a light settlement of the central pier due to landslide. The bridge was reinforced with the introduction of a supplemental thin inner reinforced concrete arch, at the intrados of the existing stone arches, externally confined by an external steel corrugated thick plate also used as formworks. In this paper the HiStrA bridge software, where the DMEM is implemented, is used for providing a structural assessment of the bridge in its original configuration and after the structural retrofitting. Both push-down and push-over analyses are performed clearly showing the efficacy of the adopted traditional retrofitting strategy.