송전철탑의 풍진동 저감을 위한 강성 및 감쇠 성능향상 = Stiffness and Damping Performance Enhancement for Reducing Wind-Induced Responses of Transmission Tower

다국어 초록 (Multilingual Abstract)

Most existing electric transmission towers are located at mountains and exposed to sudden turbulence load, which causes gust effects amplifying the tower's dynamic load. However, the transmission towers were not designed by directly considering the dynamic load amplification, and a number of them were designed by using equivalent static loads. Accordingly, increase of section area and reduction of buckling length have been widely used as one of retrofitting methods in perspective of reducing static responses. In a case of actual dynamic loading condition, reinforcing device for increasing damping performance can be considered as an alternative retrofit method. In this paper, dynamic model of the transmission tower was constructed and nonlinear time history analysis was conducted. Wind loads were obtained by wind tunnel test and friction dampers were used for increasing both the stiffness and damping of the towers. Numerical results showed that the optimal yield loads of the friction dampers were about 5-10% of the axial load of the lowest main post. And the element force of the main post and support reaction could be significantly reduced by application of toggle-type friction damper and stiffness reinforcement.

국문 초록 (Abstract)

대부분의 기존 송전철탑은 산악지형에 위치하여 강풍에 노출되어 있으며 이러한 강풍은 송전철탑에 동적하중의 증폭을 유도한다. 그러나 송전철탑은 일반적으로 이러한 동적하중을 직접 고려하지 않고, 단순히 등가정적하중을 사용하여 설계된다. 따라서 기존의 송전철탑 보강방법으로는 정적응답을 줄이는 관점에서 단면 증대나 좌굴길이 감소 등의 방법이 사용되었다. 실제 동적하중조건의 경우, 감쇠성능을 증가시킬 수 있는 보강기구가 보강방안의 대안으로 고려될 수 있다. 본 연구에서는 송전철탑의 동적모델을 구축하였고, 비선형 시간이력해석을 수행하였다. 풍하중은 풍동실험을 통해 구하였으며, 마찰감쇠기가 강성과 감쇠를 동시에 증가시키기 위해 적용되었다. 수치해석 결과는 마찰감쇠기의 최적 항복강도가 최하단 주주재가 부담했던 축하중의 5-10% 임을 보여준다. 토글형 마찰감쇠기와 강성보강을 동시에 수행함으로써 주주재의 부재력과 기초에 전달되는 하중을 크게 저감시킬 수 있었다.

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