Abstract
The structural health monitoring of power transmission towers (PTTs) has drawn increasing attention from researchers in recent years; however, no long-term monitoring of the dynamic parameters of PTTs has previously been reported in the literature. This study performed the long-term monitoring of an instrumented PTT. An automated subspace identification technique was used to extract the dynamic parameters of the PTT from ambient vibration measurements taken over approximately ten months in 2017. Ten target modal frequencies were selected to explore the effects of environmental factors, such as temperature and wind speed, as well as the root-mean-square (RMS) acceleration response of the PTT. Variations in the modal frequencies of approximately 2% to 8% were observed during the study period. In general, among the environmental factors, the temperature was found to be the primary cause of decreases in the modal frequencies, except in the case of some of the higher modes. Typhoon Nesat, which affected the PTT on July 29th, 2017, seems to have decreased the modal frequencies of the PTT, especially for the higher modes. This reduction in the modal frequencies seems to have lasted for approximately two and a half months, after which they recovered to their normal state, probably due to a seasonal cool down in temperature. The reduction percentages in the modal frequencies due to Typhoon Nesat were quantified as approximately −0.89% to −1.34% for the higher modes, but only −0.07% to −0.46% for the remaining lower modes. Although the unusual reductions in the modal frequencies are reported in this study, the reason for this phenomenon is not clear yet. Further studies would be required in the future in order to find the cause.
Highlights
The vibration-based damage detection technique is among the promising techniques employed in the field of structural health monitoring
Through the long-term monitoring data, which included data for one typhoon event, Reynders et al [28] was employed. Using this automated only modal analysis (OMA) technique and no user interactions, this study investigated the effectsthe of the environment and thewith typhoon in particular on the this study sought to identify modal parameters in of general a power transmission towers (PTTs) installed vibration sensors and identified modal frequencies
We found that the percentage of identifiability clearly in the figure, during the hit of Typhoon Nesat, the wind speed measured on the PTT exceeded the 17.2 m/s for seven hours
Summary
The vibration-based damage detection technique is among the promising techniques employed in the field of structural health monitoring. Huang et al [22] recently installed an acceleration sensor and a meteorological sensor on a transmission tower located on the Xi’an Polytechnic University campus in order to measure the vibration responses and environmental parameters of the tower over the course of one week They observed that the modal frequencies decreased as the temperature increased, and found that this relationship was quite linear. Through the long-term monitoring data, which included data for one typhoon event, Reynders et al [28] was employed Using this automated OMA technique and no user interactions, this study investigated the effectsthe of the environment and thewith typhoon in particular on the this study sought to identify modal parameters in of general a PTT installed vibration sensors and identified modal frequencies. Through the long‐term monitoring data, which included data for one typhoon event, this study investigated the effects of the environment in general
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