Proceedings of ARCH 2019 - 9th International Conference on Arch Bridges

Due to the large number of masonry bridges in the European Infrastructural network, the maintenance and retrofitting of this kind of bridges is an up-to-date issue of Structural Engineering. In this paper, the Mechanics of masonry bridges is discussed starting from the definition of load carrying structure, which is much wider than the arch itself. Once proper similarity criteria for reduced scale laboratory testing are discussed, the results of some tests are used to outline the basic features of the mechanical response of masonry bridges. Arch-Fill interaction turns out to be crucial for the l.c.c. of the bridge since it is responsible also for the span of the structural arch. The concept of Limit Load is discussed, which is not so trivial to be defined as usually assumed since it does not correspond to the Ultimate Load that activates a collapse mechanism. Once the basic issues of the dynamic and seismic response of masonry bridges are discussed, showing unexpected good seismic performances of these massive bridges, new trends in retrofitting of the bridges are discussed.