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TRENDS IN CIVIL AND STRUCTURAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping, L.F. Costa Neves, R.C. Barros
Towards Global Positioning System-Based Structural Health Monitoring
F. Casciati and C. Fuggini
Department of Structural Mechanics, University of Pavia, Italy
F. Casciati, C. Fuggini, "Towards Global Positioning System-Based Structural Health Monitoring", in B.H.V. Topping, L.F. Costa Neves, R.C. Barros, (Editors), "Trends in Civil and Structural Engineering Computing", Saxe-Coburg Publications, Stirlingshire, UK, Chapter 15, pp 319-352, 2009. doi:10.4203/csets.22.15
Keywords: structural health monitoring, global positioning system, full-scale tests, real time, structural dynamics, long duration records.
Structural health monitoring (SHM) is based on the acquisition of global and relative displacements of critical points across the structure in real time and in all weather condition. The last two constraints could be satisfied by adopting a technique based on global navigation satellites systems (GNSS).
In particular, among the satellite positioning systems (American, Russian and the future European), the global positioning system (GPS) offers continuous long term acquisitions and provides sampling rates sufficient to track the displacement of long period structures, with an accuracy of the order of sub-centimetres. It is independent from negative atmospheric conditions or large temperature variations.
The effectiveness of such a SHM solution is presently under evaluation [1-5]. First, the reliability of the GPS in collecting static and dynamic 3D movements of monitored points for real time measurements has to be assessed. Second, the uncertainty of the measurements (due to sensors placement, structural identification and diagnostic processes) has to be quantified.
The steel building which hosts the authors' laboratory is the case-study within this paper. Static and dynamic tests have been realized by comparing GPS records with those of a displacement sensor (which support the moving GPS sensor). A comparison of the data collected by GPS units with those recorded by tri-axial accelerometers has also been carried out when dynamic vibrations were induced into the structure by movements of an internal bridge-crane. Different GPS unit locations on the roof of the building are then conceived to detect any signal dilution of precision (DOP) and to assess the response of the structure under long duration excitation such as those induced by strong wind events.
The study, through an experimental full-scale tests campaign, trys to confirm that the GPS is a promising tool in the field of civil engineering, and its accuracy is consistent with the monitoring requirements for flexible structures.
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