Assessment of the Residual Prestressing Force in Existing Bridges Through the X-ray Diffractometer

The risk assessment of existing bridges requires, as fundamental factor, a reliable structural knowledge of the bridge in all its aspects. While for most of the bridges the process of knowledge and the structural analysis are simpler, for some aspects, when compared to the buildings due to the substantial absence of non-structural elements, the prestressed concrete bridges represent a particular case. Indeed, the residual prestressing force in the elements, a crucial aspect for the correct safety assessment, is often very difficult to assess, leaving engineers with several uncertainties about the effective safety level.