Data-Informed safety assessment of concrete structures

The safety assessment of existing structures is triggered by doubts regarding the actual safety, which may arise from e.g. the observation of deterioration or damage during inspections, reaching of the end of the design lifetime or unforeseen increase of actions on the structures. The safety assessment of existing concrete structures differs from the design of new structures in several aspects. The first one is the choice of the target reliability levels for the assessment and the treatment of safety requirements in semi-probabilistic verifications (e.g. setting partial safety factors for existing structures). The second one is the availability and adequacy of performance analysis models for existing structures: those given in the code for the design of new structures may no longer be valid and serve as an implicit proof of compliance for existing structures (e.g. in case of deterioration, where the limit states should be reformulated in order to include information on the suspected damage or deterioration mechanisms, task which is particularly challenging since they generally vary in space and time). The third aspect is related to the availability and use of structure-specific information: inspections, tests and monitoring may be performed to assess the structural condition, the action effect and/or the actions on structures and enable improvement of the structural assessment. In this respect, the structural engineers are faced with not always straight-forward choice of (i) the type of information needed for the assessment, (ii) the required amount of information, (iii) the location(s) where the information should be retrieved and (iv) the procedures for sound use of information in verifications. This contribution discusses the approaches to data-informed safety assessment, reflecting on the four aspects mentioned above and making distinction in the use of direct and indirect structure specific information. The contribution is outlining the vision and approach developed in the currently ongoing H2020 CSA IM-SAFE EU-project, which aims to support the preparation of the mandate for CEN for further amendment to the existing EU standards enabling data-informed safety assessment taking into account inspections, monitoring and testing. (C) Feération Internationale du Béton - International Federation for Structural Concrete.