Under urban sprawl the trend of new established complex structures has rapidly increased. In this context maintenance plays a major role and monitoring of such structures represents a first important step in combating disasters. Over the last years low-cost Global Navigation Satellite System (GNSS) equipment has faced rapid and important development opening a new door to reliable and high accurate positioning applications such as structural health monitoring. This study presents a methodology for gathering, processing and analysing 1 Hz dual frequency GNSS data acquired by a network of newly released low-cost dual frequency GNSS receivers installed on a 90 metres tall steel-concrete structure in order to sense possible wind-induced displacements. At the same time, it represents one of the first studies testing the positioning capabilities of low-cost dual frequency GNSS equipment for monitoring large-scale building infrastructure. The main tools exploited in this study are PPK relative positioning together with a multipath correction procedure based on GPS satellite constellation repeatability. In addition to these, several corrections are discussed and applied on the position estimates in order to achieve millimetre position accuracy, highly needed for sensing wind-induced displacements of large-scale structures. By artificially inducing some horizontal deformations it was found that the newly released low-cost dual frequency GNSS receiver can track centimetre order permanent deformations of tall buildings. In the context of not being able to identify strong statistical correlation between possible wind-induced deformations of the case study building and and wind data patterns, the study proves that wind-induced deflections of tall structures might be traceable only if they are larger than the magnitude of the carrier phase multipath effect that is “leaking” in the position estimates.

Under urban sprawl the trend of new established complex structures has rapidly increased. In this context little importance has been given to maintenance, even if this represents an important step in combating and avoiding disasters and developing improved future structural designs. Over the last years low-cost Global Navigation Satellite System (GNSS) equipment has faced rapid and important development opening a new door to reliable and high accuracy positioning applications such as structural health monitoring (SHM). This study focuses on assessing, from a geodetic perspective, the capabilities of a pair of low-cost dual frequency GNSS receivers for capturing the kinematic response of structures to wind. An experiment has been carried out with a stainless steel cantilever beam, aiming to highlight the advantages of employing a differential GNSS system for monitoring low frequency changes in the structure’s body. Hence, in this context the nominal precision of the GNSS system in East, North and Up direction of 4, 5 and 10 millimeter (1σ), was further improved to 3, 4 and 8 miilimeters in the presence of a Global Positioning System (GPS) based multipath (MP) correction. However, it is safer to consider that the true displacement retention potential of the low-cost GNSS receivers corresponds to 3 times (3σ) the aforementioned standard deviation values, resulting in slightly larger than 1 centimeter detectable horizontal displacements, and up to 2.4 centimeters vertical displacements. To support this, wind-induced beam displacements of up to 1.9 centimeters were identified and attested based on a cross correlation analysis with meteorological information. Next, the architecture of a GNSS based SHM system is proposed that can detect structural displacements in real time and rise safety alarms. Therefore, with real time kinematic (RTK) differential positioning and a position outlier and slip statistical testing procedure, a clear strategy for the estimation and identification of uni- or tri-dimensional displacement quantities in real time is proposed, to rise alarms about the magnitude and the direction of identified displacements. Hence, there is no doubt that newly released low-cost dual frequency GNSS receivers represent an alternative to high-end geodetic equipment for SHM, by offering an optimal balance between precision and cost efficiency.