The fundamental dynamic property of the structures is the oscillation frequency, which can be derived from the response measurements. The structures with a short/medium/long span (e.g. suspended or cable bridges) vibrate vertically rather than horizontally. The potential of GNSS precise point positioning (PPP) for detecting the dynamic response of vibrating structures has been the focus of recent studies. In this study, the usability of GNSS PPP in detecting the dynamic displacement response of a vertically vibrating structure was experimentally investigated. A number of experiments on cantilever beam structures were conducted and four cases with different vibration frequencies, ranging from 0.94 to 2.90 Hz, were selected to compare the PPP and precise relative methods in the time, position and frequency domain. In addition, the effects of the ultrarapid and final precise orbit product on the kinematic PPP solution were examined in terms of detecting vertical oscillation. The results clearly show that a high-rate kinematic PPP method can detect the fundamental frequency of vertical vibration to evaluate the dynamic movement of long/medium/short-span suspended bridges and highway viaducts.

Monitoring the response of engineering structures, such as tall buildings, tower and large-scale bridges, under severe loading conditions, such as strong earthquake or wind storm, is an important requirement to verify their design and construction and to evaluate structural condition and reliability. In the last two decades, high-rate real-time or post-processed kinematic differential Global Positioning System (DGPS) has been widely used in dynamic displacement measurements of civil engineering structures. In recent years, interest has increased for Precise Point Positioning (PPP) due to its capability to generate positioning solutions as accurate as DGPS. In this study, the potential of postprocessed kinematic PPP in terms of monitoring dynamic displacement response of a structure has been explored based on free damped oscillation events obtained from a model structure, which is able to vibrate in the fundamental and higher modes of vibration. A number of experiments have been carried out and five events, each of which is different character, have been selected to compare PPP results with DPGS results in the time and frequency domain. The results clearly demonstrate that the PPP method, like the DGPS method, offers great potential for the measurement of horizontal and vertical dynamic movement of structures. The impact of a short period (one minute) of observation length on the result of the kinematic PPP method was also investigated in terms of sensing the dynamic movement of a structure. Twenty selected one-minute data-sets extracted from a one-hour original data-set were processed by Canadian spatial reference system PPP and each one-minute PPP solution was compared with the corresponding segment obtained from the one-hour PPP solution. The results show that the oneminute PPP solution is able to extract the fundamental natural frequency of the oscillation in the horizontal and vertical component just like the one-hour PPP solution after the offset is removed and the lower frequency trend component is filtered out.

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The present study evaluates the dynamic behaviour of the Ermenek Dam, the second highest dam in Turkey, based on conventional geodetic measurements and Finite Element Model (FEM) analyses during its first filling period. In total, eight periods of measured deformation are considered from the end of construction until the reservoir reached its full capacity. The displacement response of the dam to the reservoir level and to seasonal temperature variations is examined in detail. Time series of apparent total displacements at the middle of the crest of the dam exhibits periodicity and linear trends. Correlation analysis revealed that periodic and linear displacement responses of the dam are related to variations of seasonal temperature and linearly increased reservoir level, respectively, indicating a relation between temperature, water load and dam deformation. It is also concluded that measured deformations based on geodetic data show good agreement with the predicted deformation obtained by the FEM analysis.

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