Full-scale test of a lattice transmission tower designed by the LRFD-based standard

초록

A full-scale load test was conducted to assess the feasibility and rationality of the proposed load and resistance factor design-based design standards for transmission towers in South Korea. The test involved multiple load combinations to evaluate structural integrity and load-carrying capacity. A 70.3 m transmission tower was designed and fabricated for this study. Unexpected failures occurred during the fourth load combination, and forensic investigations revealed that repeated loading and unloading caused stresses that approached the strength of the members. The load combinations were subsequently revised, and the first seven were tailored to validate the structural integrity in operational conditions, whereas the final combination assessed the ultimate structural behavior and load-carrying capacity of the tower. To comprehensively evaluate the design standards, both computational and experimental studies were performed. The safety margin for the members during the design phase was found to be at least 8 %, while analyses considering material and geometric nonlinearity indicated a safety margin of 14 %. Experimental studies confirmed a safety margin of 10 %. These results validate the rationality of the proposed load and resistance factor design-based design standards. In addition, the potential failure mechanism and vulnerable structural members under the extreme wind condition were revealed. © 2025 Institution of Structural Engineers

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