Experimental study on the bearing capacity and fatigue life of lightning rod structure joints in high-voltage substation structures

Abstract

With a 500 kV high-voltage substation structure with lightning rods taken as an engineering example, the mechanical behaviors of lightning rod joints are analyzed based on bearing capacity tests of a typical lightning rod structure and reinforced lightning rod structure. In addition, finite element models are built with ANSYS software and verified by experimental results to design an aeroelastic model based on wind tunnel tests and to calculate hot-spot stresses in the subsequent fatigue life analysis. On this basis, according to the aeroelastic model wind tunnel testing results, the fatigue lifetimes of the lightning rod structures are analyzed according to the rain-flow counting method, hot-spot stress range S-N curve and linear fatigue cumulative damage theory. The results show that the bearing capacity and fatigue properties of typical lightning rod joints cannot meet the design requirements, while reinforced lightning rod joints have a better bearing capacity and longer fatigue life because the stress concentration in the joints is significantly relieved. With the distribution of the wind speed and direction at the engineering example site, the wind-induced vibration fatigue life of the typical lightning rod structure is 11.68 years, which is far less than the mandated 50-year design period. In contrast, the fatigue life of the corresponding reinforced lightning rod structure is greatly improved and reaches 326.4 years, which indicates that the reinforcement method is efficient. Overall, the proposed fatigue life estimation method for lightning rod structure joints is feasible and workable.