Safety Evaluation Method of Transmission Tower Subjected to Special Load Case According to Broken Wires

A transmission tower was designed according to general and special load cases based on KEPCO Design Specifications. The special load case such as unbalanced load a cording to some broken wires has not been considered significantly. Therefore, this paper presents investigations on the stability and safety of main post members subjected to unbalanced load and design wind load. In this study, all cases totally considered. From the finite element analyses using LUSAS program, the stresses on the tower subjected to unbalanced load and design wind load were very high in comparison to the allowable stresses of the steel post member that was used. Some of the post member had higher stresses than the yield stress of the steel member. This paper also shows an example to improve the capacity of the post members using increased cross-section members. Based on the analyses results, when investigating the safety of the transmission tower, one must consider thenew design philosophy including ultimate strength of the member and reliability of the special loading cases.