Uncertainties in Damage Identification and Lifetime Functions of Ageing Concrete Structures

Safety and usability of existing concrete structures actually depend on the level of degradation and obsolescence due to ageing. Performance-based approaches to infrastructure management have been recently defined in terms of life-cycle-cost optimization. Lifetime functions for concrete structures can be constructed from theoretical/experimental models and, if a Structural Health Monitoring system is installed on the structure, at any required time, lifetime functions can be updated by employing a damage identification process to the data obtained from the SHM system. With reference to a real case of permanent static monitoring systems, the paper is aimed at discussing the influence of the uncertainties affecting the damage identification process on the lifetime function representing the resistance versus time of reinforced concrete beams. Based on real data, the performance estimate of the damage detection algorithms through the Receiver Operating Characteristic (ROC) curve is discussed and the probabilities of damage detection and false alarms are also formulated in terms of a Bayesian model.