Non linear elasto-plastic collapse analysis of multi-span masonry arch bridges.

An incremental-iterative procedure for the non-linear analysis of multi-span masonry arch bridges is discussed. Assuming masonry as a no tensile resistant (NTR) material with perfect elasto-plastic response in compression, the algorithm is implemented by standard programming of a commercial F.E. code and applied to different arch geometries. The effect of the arch geometrical parameters and of the material mechanical properties on the collapse mechanism is studied considering single- twin- and three-span models with both short and long piers. The classical single-span assessment approach is compared to the actual results for multispan bridges, showing that material elasto-plastic response, span interaction and pier flexibility greatly affect the limit load of both shallow and deep arches. Besides, the effect of these parameters on the collapse mechanism and on the limit load differs for shallow and deep arches, depending on the arch geometry as well