Management of Civil Infrastructure based on Structural Health Monitoring

The interest in structural health monitoring (SHM) has grown considerably in the past half century, due to an explosive growth in the availability of new sensors, the development of powerful data analysis techniques, and the increasing number of civil infrastructure that are approaching or exceeding their initial design life. In SHM, we acquire observation on the behavior of a structure to understand its condition state, based on which we decide how to manage it properly. However, this optimistic view of SHM is in contrast with what happen in real life: infrastructure operators are typically skeptical about the capacity of monitoring to support decisions, and instead of following the suggestions provided by SHM, they often act based on their experience or common sense. The reason is that at present it is not fully clear how in practice to make decisions based on monitoring observation. To fill this gap between theory and practice, I propose to consider SHM as a logical process of making decision based on observation consisting of two steps: judgment, in which the condition state of structures is inferred based on SHM data, and decision, in which the optimal action is identified based on a rational and economic principle. From this perspective, a monitoring system should provide information that can improe he managers knoledge on he srcral condiion sae enough to allow them to make better decision on the structure management. Therefore, in designing a monitoring system, the design target must be the accuracy in the knowledge of structural state achieved analyzing the observations provided by it. However, when an engineer designs a monitoring system, the approach is often heuristic, with performance evaluation based on experience or common sense rather than on quantitative analysis. For this reason, I propose a performance-based monitoring system design, which is a quantitative method for the calculation of the expected performance of a monitoring solution a pre-posteriori and for checking it effectiveness in the design phase. It is based on the calculation of the monitoring capacity and the monitoring demand the counterparts of structural capacity and demand in the semi-probabilistic structural design, and like in structural design, the solution is satisfactory if the capacity is equal or better than the demand. The choice in whether to invest a limited budget on a monitoring system or in a retrofit is another critical choice for infrastructure managers: a retrofit work can increase the capacity and the safety of a structure, while sensors do not change the capacity, nor reduce the loads. Recently, the SHM-community has acknowledged that the benefit of installing a monitoring system can be properly quantified using the concept of Value of Information (VoI). A typical assumption in the VoI estimation is that a single decision-maker is in charge for decisions on both the investment in SHM for a structure, and its management based on SHM data. However, this process is usually more complex in the real world, with more individuals involved in the decision chain. Therefore, I formalize a rational method for quantifying the conditional value of information when two different actors are involved in the decision chain: the manager, who operate the structure based on monitoring data; and the owner, who chooses whether to install the monitoring system or not, before having access to these data. The results are particularly interested, showing that under appropriate conditions, the owner may be willing to pay to prevent the manager to use the monitoring system. Application to case studies are presented for all the research contribution presented in this doctoral thesis.