Sensitivity of Structural Risk Optimization with Respect to Epistemic Uncertainties

Abstract

In the context of structural design, risk optimization allows one to find a proper point of balance between the concurrent goals of economy and safety. Risk optimization allows the designer to find the optimum level of safety for a structure, in order to minimize total expected costs. Expected costs of failure are evaluated from nominal failure probabilities, which reflect the designers degree of belief in the structures performance. Such failure probabilities are said to be nominal because they are evaluated from imperfect and/or incomplete mechanical, mathematical and probabilistic models. Model uncertainty, together with other epistemic uncertainties, are likely to affect the solution of risk optimization problems. In this paper, the concept of robust optimization is used in order to study the sensitivity of structural risk optimization with respect to epistemic uncertainties. The investigation is based on a simple, illustrative problem, but should serve as a starting point for the construction of a robust version of the risk optimization problem. This formulation should lead to an optimum point of balance between economy and safety, which is insensitive to uncertainties in the problems solution models.