Fatigue behaviour and residual service life of existing masonry arch bridges

The conservation and safety assessment of old masonry arch bridges represent nowadays a research field of considerable interest. Most of them are testimonies of the past with a significant historical and cultural value, and represent nowadays a large part of the transport infrastructures serving strategic link for roads and railways networks. In many cases their masonry primary elements are already deteriorated due to weather conditions and to the effects of cyclic traffic loads that are increased in both the frequency and the intensity with respect to the past. Even if the ultimate load is not reached, the cumulated damage along with the localised deterioration can reach levels not acceptable leading the entire structure out of service. This paper is addressed to the fatigue assessment of old masonry arch bridges with particular attention to the residual service life evaluation of the arch elements. Unlike of metals and metallic structures, little informations are available to date on the fatigue behaviour of masonry elements, also confirmed by the fact that there are no specific guidelines for assessing the fatigue limit and the residual life. The paper at first shows a critical review of the damage models for the fatigue performance assessment of masonry arch bridges. Then, an application to a case study is presented, where also the influence of intradosal C-FRP reinforcement on the residual service life and the ultimate capacity is discussed.