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RISS 인기검색어
- 검색키워드
- 저자 : Hüseyin Pehlivan (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Usability of inclinometers as a complementary measurement tool in structural monitoring
Hüseyin Pehlivan,Halim Ferit Bayata 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.58 No.6
In the last few years, many structural monitoring studies have been performed using different techniques to measure structures of different scales such as buildings, dams or bridges. One of the mostly used tools are GPS instruments, which have been utilized in various combinations with accelerometers and some other conventional sensors. In the current study, observation series were recorded for 8 hours with GPS receivers (NovAtel) and Inclination Measurement Sensors mounted on a television tower in Istanbul, Turkey. Each series of observations collected from two different sensors were transformed into a single coordinate system (Local Topocentric Coordinates System). The positional changes of the tower were calculated from the GPS and the inclination data. These changes were plotted in two dimensions (2D) on the same graphic. Thus, the possibility of comparison and analysis were found using the data from both the GPS and the Inclinometer complement each other, in the real test area. The positional changes of the tower were modeled for further examination. As a result, the movement of the tower within an area of 1×1 cm2 was observed. Based on the results, it can be concluded that inclinometers can be used for monitoring the structural behavior of the tower.
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Frequency analysis of GPS data for structural health monitoring observations
Hüseyin Pehlivan 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.66 No.2
In this study, low- and high-frequency structure behaviors were identified and a systematic analysis procedure was proposed using noisy GPS data from a 165-m-high tower in İstanbul, Turkey. The raw GPS data contained long- and short-periodic position changes and noisy signals at different frequencies. To extract the significant results from this complex dataset, the general structure and components of the GPS signal were modeled and analyzed in the time and frequency domains. Uncontrolled jumps and deviations involving the signal in the time domain were pre-filtered. Then, the signal was converted to the frequency domain after applying low- and high-pass filters, and the frequency and periodic component values were calculated. The spectrum of the tower motion obtained from the filtered GPS data had dominant peaks at a low frequency of 1.15572×10-4 Hz and a high frequency of 0.16624 Hz, consistent with two equivalent GPS datasets. Then, the signal was reconstructed using inverse Fourier transform with the dominant low frequency values to obtain filtered and interpretable clean signals. With the proposed sequence, processing of noisy data collected from the GPS receivers mounted very close to the structure is effective in revealing the basic behaviors and features of buildings.
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Hüseyin Pehlivan 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.30 No.4
Monitoring large structures is a significant issue involving public health on which new studies are constantly carried out. Although the Global Navigation Satellite System (GNSS) is the most preferable method for measuring structural displacements, total stations, one of the classical geodetic instruments, are the first devices that come to mind in cases that require complementary usage and auxiliary measurement methods. In this study, the relative displacements of the structural movements of a tower were determined using robotic total stations (RTS) and GNSS. Two GNSS receivers and two RTS observations were carried out simultaneously for 10 hours under normal weather conditions. The spectral analysis of the GNSS data was performed using fast Fourier transform (FFT), and while the dominant modal frequencies were determined, the total station data were balanced with the least-squares technique, and the position and position errors were calculated for each measurement epoch. It has been observed that low-frequency structural movements can be determined by both methods. This result shows that total station measurements are a helpful alternative method for monitoring large structures in situations where measurements are not possible due to the basic handicaps of GNSS or where it is necessary to determine displacements with short observations.
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