Nonlinear analysis procedures for safety assessment of existing RC bridges under traffic loads

The Italian infrastructural asset, mainly consisting of RC bridges, is affected by significant obsolescence: many bridges overpassed their theoretical nominal life and did not experience any maintenance intervention. Such a critical scenario is even worse if it is additionally considered the increase of vehicular traffic that occurred in the last decades. From a management point of view, many structures needed restrictions on use due to their inadequacy to withstand the traffic load provided by the current codes. This is a direct consequence of accurate safety assessments of such structures. In this paper, the opportunity to adopt nonlinear analyses for the safety assessment of existing RC bridges is discussed. The safety-format proposed in EuroCode 2 for designing new RC bridges and based on nonlinear analysis methodology is critically reviewed to consider its possible application to existing bridges. Then, the estimation of modelling uncertainty is proposed to define some acceptance criteria for the specific numerical solution strategy to be used, following the most recent international research outputs. Finally, a case study is addressed with the aim to compare linear and nonlinear results, the latter based on a calibration and verification of the adopted modelling strategy.