Abstract
Skyscrapers cause both limited sky-view and multipath error when using Global Navigation Satellite System (GNSS) measurements for monitoring structural movements. To reduce multipath errors, cut-off elevation angle can be set to a high value such as 30°−40°. However, in the case of employing high cut-off elevation angles, the use of GPS only may not provide adequate positioning solutions. To overcome this problem, Galileo and GLONASS observations are combined with GPS observations. This study experimentally investigates the contribution of multi-GNSS for studying the effects of different cut-off elevation angles on the accuracy of high-rate GNSS results for detecting characteristics of dynamic motions for structural health monitoring (SHM). The filtration design, noise level and Signal-to-Noise Ratio (SNR) of high-rate GNSS measurements of GPS-only, GPS/Galileo, GPS/GLONASS and GPS/GLONASS/Galileo are assessed for different cut-off elevation angles. The results demonstrate that the SNR of GNSS solutions for GPS/GLONASS and GPS/GLONASS/Galileo is the highest, which signifies their use in SHM. The accuracy of the dynamic movements of structures can be attained to 2 mm, on average, using multi-GNSS measurements even when using high cut-off elevation angles up to 40°. The precision of GPS/GLONASS and GPS/GLONASS/Galileo systems with different cut-off elevation angles was high when referenced to LVDT.
Highlights
Nowadays, structural health monitoring (SHM) for tall buildings in metropolitan cities is necessarily required for structures safety
The main motivation of this study is to investigate the benefit, efficiency and usability of high-rate Global Navigation Satellite System (GNSS) multi-constellation with high cut-off elevation angle for SHM and find a suitable method for estimating the dynamic behaviours of engineering structures in urban areas, such as high-rise or skyscraper, especially those surrounded by obstacles causing limited sky view and multipath error for GNSS observations
The best position dilution of precision (PDOP) under 10, 20 and 30 cut-off elevation angles were obtained by multi-GNSS observations
Summary
Structural health monitoring (SHM) for tall buildings in metropolitan cities is necessarily required for structures safety. Paziewski et al (2018) proposed a GNSS phase direct signal-processing approach technique using real-time kinematic (RTK) and PPP methods for determining dynamic displacements. They assessed the usability of multi-constellation GNSS signals for high-rate dynamic displacement detection by focusing on both the processing methodology and practical performance evaluation. Their results based on comparative analysis confirmed that all the presented method can be considered as powerful tools for detecting high-rate millimeter-level displacements. Some errors affect the GNSS accuracy for structure monitoring; multipath error, in particular, is still the primary source of error (Shariati et al 2019; Yu et al 2018)
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