Progressive collapse analysis of power transmission towers

• A 400 kV lattice tower is modelled in OpenSees program.
• The progressive collapse vulnerability of the tower is investigated.
• The force increase factors and capacity-to-demand ratios are determined.
• Pushdown analysis is used to determine the residual capacity of the structure.
• The progressive collapse probability in scenarios of higher elevations is lower.

Lattice transmission towers are critical components of power infrastructures. Collapse of a transmission tower may cause major economic and social impacts. The present study aims to evaluate the progressive collapse vulnerability of a lattice tower in a 400 kV power transmission line. The load increase factors (IF) after an instantaneous element removal are determined for application in static analyses and for design purpose. The capacity-to-demand ratios (C/D) are proposed to identify critical members after different removal scenarios. This proposed parameter is examined by comparison with Overload Factor (OF) from pushdown analysis. In addition, the pushdown analysis is used to determine the remaining capacity of the structure after removing an element. It is found that tower may resist progressive collapse because of the possible alternative load paths. It is also observed that the studied structure has less susceptibility to progressive collapse in scenarios of element removal at higher elevations.