A multi-scale approach for quantifying the robustness of existing bridges

Bridges are among the most relevant structural engineering works in transport and mobility infrastructure. De-pending on a wide range of needs and constraints, various types of structures are found: simply supported beams on piers, box girders, Gerber decks, arches, balanced systems, etc. European infrastructural heritage has now more than 50 years of working life, with increasing traffic loads and continuous ageing needs maintenance. Recent cases of existing bridge failures have opened the problem of the robustness of such systems. To this aim, a multilevel framework is formulated. This approach is needed for studying the propagation of damage from the element level to the whole structure. In the proposed multilevel approach each single part is studied and its dam-age tolerance is assessed. The effects of the damage on the single part on the overall bridge structural scheme are then assessed. This multilevel analysis allows to define a member consequence factor, i.e., a measure of the overall effects of the local damage. The proposed methodology is applied to case studies.