Horizontal capacity of single-span masonry bridges with intrados FRCM strengthening

The strengthening of masonry arch bridges, which account for a significant portion of the railway and road bridges in the world's infrastructure network, is a pressing need for the operators of such networks, and even more so in the seismic areas. As any interruptions to road and especially rail traffic are particularly costly, and consequently the most suitable solution involves the design of a strengthening system applied to the intrados of the masonry arch bridge. However, in these circumstances a more compatible and reversible solution compared to traditional strengthening techniques or FRP (Fiber Reinforced Polymer) systems involves the use of FRCM (Fiber Reinforced Cementitious Matrix). This work thus examines the effectiveness of FRCM strengthening on the intrados of masonry arch bridges, taking into account the actual geometric relationships that characterise the arches of bridges and considering the effect of Coulomb friction. The results obtained using lower bound limit analysis highlight the optimal conditions for the use of this strengthening, and the situations in which, due to the actual geometry of the bridges and the friction coefficient value, the use of this strengthening system would not be recommended.