Fatigue assessment of old existing masonry arch bridges: critical review of research and application to a case study

The conservation of old masonry arch bridges is nowadays a very interesting engineering challenge since mostly of them are still in service and are subjected, differently from the past, to higher and more frequent traffic loads. Therefore, it is very important to properly predict the actual behavior under cyclic loadings taking into account the fatigue strength of the masonry and its resistance degradation due to repeated loads. In this paper modeling criteria and assessment procedures of masonry arch bridges are being critically reviewed. A particular attention is given to the fatigue behavior under cyclic loads and to residual life evaluation. The paper concludes with some numerical investigations on an existing multi-span Italian masonry bridge with backfill above the arches in order to assess the fatigue bridge capacity.