Investigation of load-carrying capacity and failure mechanisms in full-scale testing of a re-fabricated transmission tower

This study presents full-scale experimental testing of a re-fabricated structure that previously experienced premature failure during load testing. A total of seven loading tests and one failure test were conducted. The structure successfully withstood 100% of the applied loads in all tests, demonstrating its structural integrity. However, discrepancies emerged between the computationally predicted and experimentally observed ultimate failure modes and load-carrying capacities. Insufficient bolt tightening during assembly was hypothesized to reduce rotational stiffness, potentially altering the failure mechanism and load capacity. Localized connection analyses revealed that reduced bolt tightening forces significantly decreased rotational stiffness. By varying rotational stiffness in the re-fabricated structure's main post segment joints, the failure mechanism, load capacity, and ultimate failure location were evaluated. The findings confirmed that incomplete bolt fastening can critically affect a structure's failure behavior and performance. This study emphasizes the importance of thorough inspections of bolted connections during the maintenance of transmission towers to ensure structural reliability and prevent potential failures.