The importance of sustainability and resilience in the design and assessment of structures has increased significantly over the past years An adequate and efficient assessment of concrete structures in the wake of adverse events such as fire can help achieve this, by ensuring that refurbishment and demolition are not needlessly pursued, while at the same time not compromising on safety Current practice is however far from this goal, as the many uncertainties associated with fire exposure and residual mechanical properties are not sufficiently taken into account, and appropriate non-destructive testing mechanisms are lacking Recently, a methodology for quasi-distributed output-only model strain identification has been developed at KU Leuven It is very promising for post-fire assessment as it allows for a detailed assessment of the stiffness of structural elements In the proposed research, this methodology will be combined with post-fire assessment tools developed at Ghent University for a rational post-fire assessment This requires fundamental research into (i) the post-fire behavior and safety of concrete elements; (ii) the evaluation of post-fire characteristics through vibration-based testing; (iii) the optimum vibration-based test program in the wake of a fire event; and (iv) a rational methodology for updating the post-fire assessment with the vibration-based test results To validate developed methodologies, also an experimental test program will be performed