The value of information in structural performance assessment

The need for improved procedures for civil infrastructure management has prompted a great deal of research in global structural condition assessment in recent years. In theory, global methods can identify damage in structures based upon changes in a small set of structural parameters obtained from full-scale measurements. Despite the fact that many new damage detection methods are being proposed, there remains a need for an objective means of estimating the utility of these new techniques.; Using a systems-based approach, a rational means was developed for evaluating the utility of structural condition assessment techniques. The approach considers both the engineering and the economic merits of damage detection methods in a unified fashion, in order to assess the value of the information that a given technique can provide to the management decision process. A Partially Observable Markov Decision Process (POMDP) provided a computationally tractable modeling framework that was readily adapted to this problem.; The POMDP modeling framework was applied in two application examples. The first example, which consisted of a hypothetical highway bridge system, demonstrated that a damage detection method must exceed a threshold of utility such that the information it provides can effect a noticeable change on management policy. The second example was a prototype problem designed to highlight each of the modeling tasks involved in applying the POMDP framework to a structural management problem. The following features were included: (1) mathematical descriptions of the dynamic mechanisms that influence the evolution of a structure, such as resistance deterioration, loading, and maintenance, (2) means of probabilistically relating observations of damage and the resistance of a structure, and (3) a means of characterizing costs associated with inspection strategies and maintenance activities. As part of this example, a quantitative approach for assessing the expected value of information provided by damage detection measurements was demonstrated. Several important lessons were learned from the application examples regarding the balance that must be achieved between accuracy and cost before a damage detection method can be considered worthy of implementation. Many of the conclusions drawn herein can be extended to systems of greater complexity.