Operational modal analysis of historical constructions using commercial wireless platforms

Operational modal analysis is currently applied in structural dynamic monitoring studies using conventional wired-based sensors and data acquisition platforms. However, this approach becomes inadequate in cases in which aesthetic concerns arise (e.g., in cultural heritage buildings) or in which the use of wires greatly impacts the monitoring system cost and creates difficulties in the maintenance and deployment of the data acquisition platforms. In these cases, the use of a WSN and MEMS would clearly benefit the applications. This work illustrates an attempt to apply the wireless technology for the structural health monitoring of historical masonry constructions in the context of operational modal analysis. The article presents the state of the art of the wireless monitoring systems making a review of the applications in the civil engineering field. Subsequently, commercial wireless-based platforms and conventional wired-based systems are applied to study one laboratory specimen and one structural element from a 15th Century building located in Portugal. The results achieved in this study showed that, in comparison to the conventional wired sensors, the commercial wireless platforms have poor performance with respect to the acceleration time series recorded and the detection of modal shapes. However, reliable results were obtained for the measured frequencies.