Analysis of transmission line tower subjected to wind loading

Abstract

Heavy electrical transmission lines are carried by transmission line towers at a suitable and safe height above the ground. These towers must bear its own weight and distress created by transmission line wires. Despite that it should also survive against all-natural factors such as fierce winds, earthquakes, and snow loads. For a safe and cost-effective design, transmission line towers must fulfil both all structural and electrical standards. This manuscript discusses the numerous types of transmission towers and their configurations as per the Indian Standard IS 802:2015. Further this paper contains the details of the design and simulation of 500 kV double circuit conductors, which is one of the commonly adopted transmission towers. For the said purpose STAAD Pro. V8i Select Series, computation tool has been adopted which is based on the finite element computations. During computational analysis wind load, structural dead load, and seismic load according to IS:1893:2002 (part 1) has been considered. The clearance from the ground (h1), the lowermost conductor wire's maximum sag (h2), conductor wires' vertical spacing (h3), and the distance between the earth wire and the highest conductor wire in terms of vertical distance (h3), all are added up to get the final height of transmission tower which is 43.5 m. The earth wire is also known as the ground wire, is always sited at the very topmost of the steel tower. It features an 8.32 m square base with a width of 8.32 m. The three major phases of the fragility analysis procedure for transmission towers under wind loading are as follows: Nonlinear dynamic analysis, regression analysis, and creation of Wind loadings and uncertainty models. After that, the random variables and probability distributions corresponding to them are examined. Finally, based on the commonly adopted transmission towers a hypothetical case study has been conducted for a real-world functioning tower which is subjected to wind loading along with other critical loadings. The obtained result shows that if we are considering a larger number of uncertain characteristics, then it causes the fragility curve to become more disperse, and further it is observed that the angle of attack for the wind load has a substantial effect on the fragility curve.