Wind Hazard Fragility Analysis of Transmission Free-standing Towers Using Quasi-static Method

It is significant to understand the wind disaster prediction and operations management so as to evaluate the wind resistance bearing performance and safety margin on existing transmission tower. In this paper, an effective method of tower fragility considering varies wind direction is carried out. Firstly, based on the principle of wind engineering, a quasi-static analysis framework is applied to determine the extreme probability distribution of wind load of tower under different design wind speeds. The uncertainty and initial defects of structure, which include wind bearing capacity performance and corresponding failure criterion of tower structure are investigated later by using nonlinear static pushover analysis (NSPA). The next step is obtaining the probability model of the wind bearing capacity of structure using random sampling analysis, and finally the wind disaster fragility curve of the tower under different wind direction can be calculated by using limit state function. This study shows that: 1) the probability distribution of wind effect based on quasi-static analysis framework can be obtained by using the first transcendental probability theory. 2) On the other hand, the quasi-static base shear response is not affected by the nonlinear status of the structure, and can be used as an evaluation indicator of the overall wind load. 3) Based on the internal relationship between yield failure and overall failure, a reasonable failure criterion of slight, severe and collapse can be established. 4) The wind angle has a significant influence of the wind bearing capacity and the tower vulnerability. In this paper, the tower has the highest vulnerability probability under the wind angle of 60°. © 2024 Chin.Soc.for Elec.Eng.