In this paper, the dynamic snapping of the 3-free-nodes spatial truss model was studied. A governing equation was derived considering geometric nonlinearity, and a model with various conditions was analyzed using the fourth order Runge-Kutta method. The dynamic buckling phenomenon was observed in consideration of sensitive changes to the force mode and the initial condition. In addition, the critical load level was analyzed. According to the results of the study, the level of critical buckling load elevated when the shape parameter was high. Parallelly, the same result was caused by the damping term. The sensitive asymmetrical changes showed complex orbits in the phase space, and the critical load level was also becoming lowly. In addition, as the value of damping constant was high, the level of critical load also increases. In particular, the larger the damping constant, the faster it converges to the equilibrium point, and the occurrence of snapping was suppressed.

가섭선 및 애자가 연결되어 있는 복잡한 구조물인 송전철탑의 3차원 모델링을 통하여 동특성을 파악하고, 풍하중에 대한 응답 특성을 정적, 동적 및 좌굴 해석을 가섭선의 절단 유무에 따라 분석하였다. 우선, 고유치해석을 통해, 송전철탑이라는 구조시스템이 일반 건축물과는 달리 극소수의 저차 모드가 구조물의 동적 거동을 좌우하지 않고, 상대적으로 많은 모드들이 동적 거동에 기여한다는 것을 확인하였다. 두 번째로, 정적 해석과 좌굴 해석을 통해, 대상 구조물이 정적인 개념의 풍하중에 대해서 구조적으로 안전하고 좌굴에 대해서도 충분한 안전율을 확보하고 있음을 확인하였다 그러나, 모든 가섭선이 단절되는 극단적인 경우에는 안전율이 상당히 낮아졌으며 이러한 경우에 구조물의 붕괴 및 전도를 방지할 대책에 대한 검토가 필요하다고 사료된다 마지막으로, 풍하중의 시간에 따른 변화를 고려한 동적해석을 통해, 풍하중의 동적 변동성분이 구조물의 응답을 증가시키고 있음을 확인하였다.

This paper describes dynamic characteristics of a power transmission tower consisting of lots of power lines and insulators. A numerical 3D modeling for the static, dynamic and buckling analyses of the power transmission tower is presented considering the case when the power lines are cut. Eigenvalue analysis indicates that the transmission tower shows different behavior comparing to usual structures governed by several low modes. The transmission tower is governed by lots of modes. It is verified that the transmission tower is structurally safe against the static wind and buckling loads. But the structural and buckling safety is not guaranteed when all power lines are cut, which comes to collapse the transmission tower. Further study is in need to overcome such case. Wind dynantic analysis shows that fluctuating wind loads increase the response of the tower.