Structural monitoring of “Himera” viaduct by low-cost MEMS sensors: characterization and preliminary results

The term structural health monitoring (SHM) usually refers to the process of implementing a damage detection strategy for aerospace, civil or mechanical engineering infrastructures. Under an extreme event, such as an earthquake or unanticipated blast loading, SHM could be used for rapid condition screening, to provide, in near real time, reliable information about the performance of a structural system during the event and about the subsequent integrity of the system itself. On the other hand, owners of buildings and civil infrastructures need information on the actual state of the structures in order to realize effective life-cycle management plans and reduce the economic and social impact of maintenance. In fact, inspections and repairs entail huge direct and social costs due to the interruption or reduction of the structure serviceability. Such information can be collected and elaborated by means of adequate monitoring systems but their diffusion is still limited by the high cost of sensors and devices needed. In this work, the realization of a monitoring system on some bridge piers of the “Himera” viaduct, located in Italian A19 Palermo–Catania highway and recently damaged by a landslide, is presented. The proposed monitoring system aims to observe the global stability of the un-collapsed side of the viaduct during the demolition works of the other side and it is intended as a quasi-real-time alert tool able to send data and warning messages to an operations center. In order to contain costs, low-cost micro electronic mechanical system sensors have been used for the monitoring. The architecture and main features of the developed monitoring system are described in detail and the preliminary results, recorded during the first months of the campaign, are reported and discussed. Since the proposed monitoring system is still a prototype, it has been necessary to provide a metrological characterization campaign in laboratory conditions in order to define a calibration law to correct the acquired data and to estimate the sensitivity and the accuracy of the measurements. The results proved that the proposed system can be used for the monitoring of civil structures and infrastructures.