Reliability Analysis of Structures Under Hybrid Uncertainty

In engineering applications it is important to model and adequately treat all the available information during the analysis and design phase. Typically, the information are originated from different sources: field measurements, experts’ judgments, objective and subjective considerations. Over these features, the influences originated from the human errors, imperfections in the construction techniques, influence of the boundary and environmental conditions are added. All these aspects can be brought back to one common denominator: presence of uncertainty. The uncertainty can be viewed as a part or class of imperfection in the information that attempts to model a system behavior in the real world (see Fig. 1). It is the gradual assessment of the truth content of postulation e.g., in relation to the occurrence of a defined event. Normally, the uncertainty is viewed in two categories, namely aleatory and epistemic. The aleatory uncertainty is classified as objective and irreducible uncertainty with sufficient information on the input uncertain data. These are inherently connected to the problem at hand and cannot be influenced by the designer. The epistemic uncertainty is classified as subjective and reducible uncertainty that stems from the lack of knowledge about the input uncertain data. It arises from the cognitive sources involving the definition of certain parameters, human errors, inaccuracies, manufacturing and measurement tolerances, etc.