Quantifying the Benefit of Structural Health Monitoring: Can the Value of Information be Negative?

Abstract

Structural Health Monitoring (SHM) is generally presented as a powerful tool that allows bridge managers to make decisions on maintenance, reconstruction and repair of their assets. The benefit of SHM can be properly quantified using the concept of Value of Information (VoI), i.e. the difference between the utilities of operating the structure with and without the monitoring system. In calculating the VoI, a commonly understood assumption is that all decisions concerning system installation and operation are taken by the same rational agent. Conversely, in the real world the individual who decides on buying a monitoring system, the owner, is often not the same individual, the manager, who will use it, and they may behave differently because of their different risk aversion. In this contribution, we demonstrate that in a decision-making process where the two individuals involved share exactly the same information, but behave differently, the VoI can be negative. Indeed, even if the two agents have an agreement a priori, their optimal actions can diverge after the installation of the monitoring system, due to their different behaviors; this scenario could generate a negative VoI from the owner’s perspective. We propose a qualitative and quantitative formulation to evaluate when and under which circumstances the VoI can be negative, if the owner differs from the manager with respect to their risk prioritization. To illustrate how this framework works, we evaluate a hypothetical VoI for the Streicker Bridge, a pedestrian bridge in Princeton University campus equipped with a fiber optic sensing system, assuming that two fictional characters are involved: Malcolm the manager and Ophelia the owner. The results demonstrate that when the owner, because of the manager’s different behaviour, is forced to undertake an action she would not choose, her VoI becomes negative, i.e. it is not convenient for her to install the monitoring system. This framework aims to help the owner in quantifying the money saved by entrusting the evaluation of the state of the structure to the monitoring system, even if the manager’s behavior toward risk is different from the owner’s own, and so are his management decisions.