Study on the Effect of Bolt Slippage and Foundation Settlement on the Bearing Capacity of Tower-Line System

The bolted joints of angle steel transmission tower will slide relatively under load, that is, the bolt-slippage effect. The existing research on the bearing capacity of transmission towers often ignores the bolt-slippage effect, resulting in deviations in the analysis of the bearing capacity of transmission towers. To evaluate the bearing capacity of transmission tower more accurately, the finite element model of transmission tower considering bolt-slippage effect and the finite element ideal rigid frame model of transmission tower without considering bolt-slippage effect are established. The distribution and stress changes of failure members of the two models under static wind load and longitudinal unbalanced tension caused by uneven icing and wire breakage under different settlement modes and settlement amounts are calculated. The difference of bearing capacity between the two models is compared and analyzed, and the influence of bolt slippage and foundation settlement on the two models is obtained. The results show that the bolt-slippage effect will significantly increase the deformation and displacement response of the transmission tower, and at the same time affect the stress distribution of the members, resulting in the failure position and failure mode of the members of the two models are not exactly the same. Ignoring the bolt-slippage effect will overestimate the bearing capacity of the transmission tower-line system. The bolt-slippage effect makes the bearing capacity of the tower-line system decrease more slowly with the settlement. To calculate the bearing capacity of the tower-line system more accurately, the bolt-slippage effect cannot be ignored.