Power transmission lines are among the inseparable components of an electric power system. In these lines, conductors are the main mean of electrical energy transmission. The other structural components like electricity towers should be designed so that the conductors can properly perform their main function, i.e., the transmission of the required electrical current or charge. The progressive collapse of a structure is caused by the occurrence of accidental events, and the chainlike effect of failure results in the fracture of a wide range of the structure or even its full collapse. The failure of the electricity transmission line structures caused by the loads resulting from strong winds and ice is a major problem in electricity companies throughout the world. The transmission towers have very complex structures. Therefore, it is very difficult to simulate the real damage and progressive collapse in them. Modeling the electricity transmission lines based on a real model provides more real and accurate results and leads to a more proper analysis.
This research has evaluated the progressive collapse behavior of a case study on the 230-kV electricity transmission line in the Fars Province, Iran. The two methods of linear and nonlinear dynamic analyses were employed to identify the damage using the alternate path method. The finite element models of a tangent electricity tower (DC0) and an terminal one (DC90) were simulated along with the conductors of the 230-kV electricity transmission line in the SAP 2000 software. The study evaluated the effect of removing the legs of the electricity transmission tower. The progressive collapse behavior was simulated and evaluated under the loading conditions, wind load, freezing caused by snow, and simultaneous wind and ice load. In the linear dynamic analysis, the ratio of demand to capacity and the displacements of the removal point at the topmost point of the tower (tower tip) were assessed. In the nonlinear dynamic analysis of