Effect of material strength uncertainties on the structural assessment of existing RC bridges

The structural assessment of existing bridges is a topic of noteworthy interest for the engineering community given the general conservation state characterizing the infrastructural assets and the need of performing upgrading interventions. One of the key aspects of this process is represented by the material strength definition based on destructive and non-destructive tests. As for reinforced concrete structures, the design strength determination of both reinforcing steel and concrete should account for the statistical distributions of strength values returned by tensile and compressive tests, respectively, as well as the related confidence factors assumed for the analysis. In this context, existing reinforced concrete structures commonly exhibit a notable dispersion of resistance values making necessary the adoption of improved approaches for design strength determination. The present paper addresses this topic by analyzing the effects of uncertainties on the capacity assessment of reinforced concrete elements which are typical of Italian bridges realized during the last century. The study aims at highlighting how the knowledge process based on investigation campaigns can influence the capacity assessment of existing structures.