Effect of prestressing corrosion on failure in bridges

Infrastructures (viaducts, bridges, tunnels, railways, and roads) are fundamental to allow people and goods move around a country. In particular, in Italy, due to its orographic and morphological complexity, the ratio between the number of viaducts and the national geographical extension is the largest in Europe. This kind of structure constitutes a weakness of the road networks, especially those over 50 years old, and among these, prestressed concrete structures are the most vulnerable. Therefore, the study of the robustness of an infrastructure network is a quite useful topic for modern societies and public mobility managers. The aim of the present work is to develop a reliable and fast analysis tool capable of processing many structures in a relatively short time. In order to calibrate the most suitable instrument, starting from the study of an experimental campaign on six prototypes of artificially corroded posttensioned concrete beams, the reliability of concentrated plasticity models was investigated to reproduce force-displacement diagrams and in particular, the effect of corrosion on the moment-curvature relationship. In fact, this method could provide a well-defined nonlinear analysis of prestressed elements, especially in the case of grillage decks where external girders could be more affected by corrosion damage in opposition to internal girders or diaphragms. A numerical model by FEM analysis is also presented to reproduce a vulnerability study on an actual structure.