Assessment of Multi-Span Masonry Arch Bridges. Part II: Examples and Application

Modern approaches to multi-span masonry bridges are approximate in many ways: load distribution, masonry degradation, fill/barrel, span/span and span/pier interaction are taken into account by means of approximate models or are neglected at all. At the end of the assessment procedure, the approximation to the load carrying capacity of the bridge cannot be easily quantified. In the Part I of this paper, an extension of the classical approach to masonry arches was formulated taking into account the non linear response of masonry, a limit to compressive plastic strains and assuming simplifying but conservative assumptions. The procedure allows the analysis of multi-span masonry bridges considering the non linear response of arches and barrels and the mutual interaction. The response of 2- and 3-span prototypes is compared to that of single arch; than the procedure is than applied to a six 18.5m/span in-service viaduct. A detailed comparison with the single-span-bridge approach is discussed. Specific attention is paid to the evolution of the collapse mechanism and to the effect of load distribution, addressing the concentrated loads/distributed equivalent loads problem and showing how the limit to compressive inelastic strains, i.e. to masonry ductility, may be of great importance to the structural analysis of masonry bridges