Experimental validation of the transmission tower designed using load and resistance factor design method in South Korea

This study proposes and validates a load and resistance factor design (LRFD)-based approach for 345 kV transmission towers in South Korea. A new tower was designed following LRFD principles and compared to an existing tower developed using the conventional allowable stress design (ASD) method. The LRFD-based design achieved an approximate 11% reduction in structural weight by optimizing member sizing. Structural vulnerabilities and nonlinear failure behaviors under critical load combinations were first identified through finite element analysis and subsequently verified via full-scale load testing. The experimental program assessed structural performance under four major LRFD load combinations and benchmarked the results against those derived from ASD conditions. Additionally, the ultimate strength and failure characteristics were investigated under extreme wind loading with all conductors intact. Despite the reduced member sizes, the LRFD-designed tower satisfied all load-bearing requirements. The failure test, conducted by incrementally increasing the applied load, revealed a buckling failure at 135% of the design load, closely aligning with the nonlinear analysis predictions. These findings confirm that the proposed LRFD-based approach ensures both structural reliability and material efficiency, offering a valuable reference for the optimization and enhancement of future transmission tower designs.