Analytical vulnerability assessment of electric distribution networks using laboratory-based fragility curves under wind-ice loading

Overhead electric distribution networks are highly vulnerable to storms, and their vulnerability increases significantly during events accompanied by wind and ice. Under such conditions, ice accretion on conductors increases their weight and imposes additional forces on supporting poles. Since the tensile strength of conductors is typically much higher than the mechanical resistance of concrete poles, and each pole is subjected to the forces of at least three conductors, pole failure is often the dominant failure mode. Given limited financial resources for infrastructure reinforcement, it is essential to identify and prioritize the most vulnerable points of the network using fragility-based approaches to support resilience enhancement strategies. This study proposes a novel analytical framework for assessing the vulnerability of distribution networks under concurrent Wind–Ice conditions. The method derives fragility curves for network components through extensive experimental testing of poles and conductors, and then applies probabilistic analysis to calculate section-level failure probabilities and rank feeder sections according to their vulnerability. The results show that the fragility behavior of both poles and conductors can be accurately captured using logistic functions. Moreover, the sensitivity analysis indicates that for the studied scenarios both increasing wind speed and ice thickness lead to higher network vulnerability, with the greatest impact observed under simultaneous conditions of strong winds and heavy ice. The proposed framework effectively identifies vulnerable sections of the distribution network and provides actionable insights for enhancing network resilience against concurrent wind–ice events.