Effect of modelling complexities on extreme wind hazard performance of steel lattice transmission towers

Abstract

Reliable computational models of transmission towers are key to improved hurricane risk management of transmission systems. However, a comprehensive understanding of involved complexities and their effects on the extreme wind performance of towers is not available. Particularly, buckling effects have not been captured properly and the failure of joints and the post-buckling behaviour of towers have not been investigated. Moreover, contributions of these and other complexities to key tower responses in the presence of uncertainties are not known. This paper presents an approach to modelling lattice towers that captures buckling and post-buckling, and joint slippage and failure and analyses their effects, while considering uncertainties, through a set of probabilistic, nonlinear pushover analyses in OpenSEES. Results for a double circuit vertical lattice tower indicate that buckling can lead to 30% reduction in the load-bearing capacity of towers. Joint slippage reduces the load-bearing capacity of the tower by 6%. It also considerably increases tower displacement. Connection failure can also occur in rare cases and it subsequently, changes tower’s failure mode. The proposed modelling approach can be used in risk analysis of transmission systems to investigate various performance levels and improve the design of towers.