Probabilistic Reliability Assessment of Historical Structures

The reliability assessment of heritage structures represents a complex issue beyond traditional assessment procedures. Probabilistic methods and Bayesian updating techniques are often invoked in order to properly handle the uncertainty in the assessment process and obtain realistic reliability estimation. However heritage structures have been often subjected to alteration over the course of their working life, referring with this term to modifications to the structural scheme and deterioration processes. Modification and degradation are seldom documented and not easily recognizable; furthermore, they usually lead to weak points and defects that have a great impact on the structural integrity. Disregarding these anomalies entails a misunderstanding of the structural scheme that may leads to an unacceptable error in the reliability assessment. In this paper a procedure for the assessment of existing buildings that considers the implementation of probabilistic methods and Bayesian updating techniques has been proposed. The key step of the flow chart is represented by the analysis and identification of structural alteration. The procedure has been validated with an application to a relevant case study; results reveal that probabilistic methods represent a powerful tool in assessing historical structures, provided that the sensitiveness of the result to uncertainty regarding structural alteration is duly taken into account.