Numerical and Experimental Failure Analysis of Steel Components in a High-Voltage Transmission Tower Structure

The present study aimed to delve into the root cause failure analysis of a carbon steel member (Grade Q235C) within a high-voltage transmission tower which was subject to self-weight (approximately 43 kg) and wind load only (calculated at 2787.35 Pa). Examination of the fracture surface revealed the presence of beach marks and ratchet marks which indicates that the carbon steel member (a square hollow section equipped with two bolted supporting plates positioned 1.7 meters away from the failed welded plate) experienced failure attributed to wind-induced fatigue along the weld joint. No abnormalities were observed in the microstructure and the weld zone predominantly featured a ferrite phase and grain boundary pearlite. However, the finite element analysis conducted using Abaqus software demonstrated that the steel member at the weld joint should not have failed under normal circumstances. The critical finding was that the failure occurred due to the loosening of bolted supporting plates located within a distance of 1.7 meters from the welded joint. As a consequence of the supporting bolted joint becoming loosened, a Von Mises stress of approximately 400 MPa manifested at the welded joint, resulting in an abrupt failure.