Integrated systems for Structural Health Monitoring

When designing a Structural Health Monitoring system, one should always focus on the specific requirements of the structure under exam. The first step in the design process consists in identifying the probable degradation mechanism and the associated risks, in cooperation with the structure's owner and designer. Next, the expected responses to these degradations are established and an appropriate Structural Health Monitoring Systems is designed to detect such conditions. Only at this stage, the appropriate sensors are selected. Once the sensors are installed and verified, data collection can start. If these logical steps are followed and the monitoring data is correctly acquired and managed, data analysis and interpretation will be greatly simplified. On the other hand, if one designs an SHM system starting from a specific sensor system, it often ends up with a large quantity of data, but no plans on how to analyze it. When selecting the best sensors for the specific risks associated with a given structure, it is often necessary to combine different measurement technologies. As an example, a cable stayed bridge could require fibre optic sensors for strain monitoring, a corrosion monitoring system for the concrete pylon, vibrating wire load cells for measuring the stay forces and a laser distance meter to observe the global deformations. To insure that the data form these systems if correctly fused and correlations between the measurements can be found, an integrated data acquisition and management system is required. Our experience has shown that the use of relational database structures can greatly simplify the handling of this large and heterogeneous data-flow. With as appropriate data structure, the measurement data and other related information on the monitoring network, the structure and its environment can be organized in a single repository that will follow the structure's life in the years. This paper presents a generalized architecture for SHM monitoring system combining multiple sensing technologies and several application examples to real structures, including bridges, buildings and dams.