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Title |
Long-term Displacement Measurement of Bridge Structures Using a Total Station
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Authors |
김경원(Kyungwon Kim) ; 심성한(Sung-Han Sim) ; 이영주(Young-Joo Lee) ; 이준화(Junhwa Lee) ; 이승준(Seungjun Lee) |
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DOI |
https://doi.org/10.11112/jksmi.2026.30.3.87 |
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Keywords |
토탈스테이션; 장기 변위 계측; 리플렉터; 평면 법선벡터; 교량 모니터링 Total station; Long-term displacement measurement; Reflector; Plane normal vector; Bridge monitoring |
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Abstract |
Accurately measuring the long-term displacement trend of bridges during and after construction is essential for structural safety assessment.
Conventional total-station-based displacement measurement requires the instrument to remain fixed for long periods, and self-motion compensation using a single fixed-point reflector has inherent limitations. This study proposes a method that places four reflectors at the outer corners and one at the center of the bridge underside, defines a base plane from the four outer points, and computes the reference-plane-based camber of the deck as the signed perpendicular distance from the center reflector to the plane. The derived camber is mathematically invariant to rotation and translation of the total station coordinate frame; thus, repeated installation and removal of the instrument does not break the temporal continuity of the camber time series, making the method suitable for intermittent monitoring over long durations. A 16-day field validation on a vehicle/pedestrian bridge showed that the proposed method repeatedly observed daily camber variations of 2-4 mm above an outer-plane residual RMS noise floor of about 0.77 mm.
The weather comparison used ambient temperature and shortwave radiation from a public weather archive. The zero-lag correlation with ambient temperature was weak (Pearson r=+0.23), while a 5 h lag comparison increased the correlation to r=+0.61, indicating a delayed thermal response tendency rather than direct accuracy validation.
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