"Precise Monitoring of Horizontal Displacement of Large-Scale Structures using Low-Cost Dual Frequency GNSS Receivers"

Abstract

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.