Uncertainty sources in the structural assessment of masonry arch bridges: a case study of a single-span stone arch bridge

In this work, the evaluation of some of the most common uncertain parameters present in the structural assessment procedure of masonry arch bridges is addressed. The Xuño Bridge, a single- span stone arch bridge located in Galicia (Spain) is considered as a case study. This structure presents the particularity that after hundreds of years, all its constructive elements have disappeared except the arch barrel. Thus, the typical scattering in the thickness of this element can be measured and quantified. For that purpose, an in-situ terrestrial laser scanner survey was conducted, acquiring its exact geometry. An uncertainty analysis, considering geometrical and material parameters, was then conducted with the aim of estimating the impact of the uncertainty sources in the prediction of the collapse load of the arch. Two different numerical modeling strategies were employed, the limit analysis approach and the finite element method. A sensitivity analysis was finally performed to identify the critical parameters on the response of the structure.