Guyed towers in high-voltage transmission lines consist of the tower body, guy wire system, and foundation. A well-designed guy wire system with optimized tension levels is essential to maintain the stability of the tower under wind loads and other external forces. In practical operation, to prevent excessive corrosion of the pinned metal components at the tower base, these connections are often encased in concrete, altering the base connection conditions and affecting the structural forces on the tower. This study develops a finite element analysis model based on two guyed tower structures from a high-voltage transmission line project. By measuring the actual tensions of the guy wire and testing the basic material performance, this model considers the effects of varying base connection conditions and different guy wire tension levels. Under designed ice load and extreme wind load conditions, the analysis focuses on changes in tower body stress, tower-top displacement and inclination, and guy wire forces. The results indicate that when the tower base is uniformly pinned or fixed, the initial guy wire tension has minimal impact on maximum tower stress but significantly affects maximum tower displacement and inclination when the tower was under the ice and wind load conditions. The base connection condition has a pronounced impact on the stress states of the tower and guy wire system, especially under the designed wind loads. In particular, when the base is fixed, the maximum base stress in Tower 1 under the wind loads is 270% higher than in a pinned condition. The initial guy wire tension level significantly affects the guy wire force under the ice and wind loads; for example, when Tower 1 is subjected to approximately 85% of the design level of high wind load, some guy wires reach full relaxation prematurely, presenting localized strength failure risks at the tower foot, potentially threatening the tower safety under extreme design loads.
