A Framework to Define an Effective Structural Health Monitoring (SHM) System Using the Data from OMA Test

To design an effective structural health monitoring (SHM) system it is essential to decide the optimum number and the location of sensors. In this way an accurate estimation of monitoring parameters can be assured reducing at the same time the costs during the installation and operational phases. During the years, many Optimal Sensor Placement (OSP) techniques have been proposed for designing the best sensing locations, which are used to estimate modal parameters based on vibration response. However, the target modes for OSP techniques are selected from preliminary studies on Finite Element (FE) models while in this paper the use of data acquired during a previous Operational modal Analysis (OMA) test is studied with reference to a benchmark case study. The selected case study is a pre-stressed reinforced concrete bridge already dynamically identified with an innovative wireless sensor network that will be used for a future SHM system. In the paper, different OSP techniques including effective independence (EI), average driving point residue (ADPR) and Eigenvalue Vector Product (EVP) methods are applied and discussed with reference to the selected case study. Then a framework for deciding the optimum number and location of sensors using the data from OMA test is developed. In particular, the optimal criterion defined is based on Modal Assurance Criterion (MAC) between the exact and interpolated mode shapes from an optimal sensor set. The proposed case study demonstrates the efficiency of the framework to op-timize the number of sensors using the experimental data from a previous OMA test.