Structural Performance of Bolted Connectors in Retrofitted Transmission Tower Leg Members

Upgrading aging transmission towers to meet the requirements of increased loads due to additional equipment and updated loading standards has attracted interest from researchers and engineers throughout the world. Retrofitting of tower leg members by adding parallel reinforcing members has been verified as an effective way to increase structural load-carrying capacity. The structural performance of the connector between reinforcing members and main members is the controlling factor in this kind of retrofitting design. In this paper, the static structural performance of bolted cruciform/splice connections in reinforced leg members was reviewed and numerical models were developed for dynamic analysis of the connections under cyclic loads using ANSYS. The bolt pretension relaxation was simulated and its structural effect on bolted cruciform/splice connections was studied. Results demonstrated that the bolt pretension loss causes high initial stiffness degradation and this effect is more influential on cruciform connections than splice connections.