The state-of-the-practice for the design of transmission line structures is commonly governed by loading caused by wind/ice combinations and broken wire forces. However, earthquake effects are not commonly considered in transmission line structural design, even in high risk seismic areas. This report discusses the seismic effects on major transmission line components, and includes example problems that provide an overview of the potential impacts of seismically induced differential settlements and lateral spreading.
Value to Electric Cooperatives
Transmission lines and their major components are critical infrastructure for electrical power transmission and are used throughout the world. A survey conducted as part of this project shows that the majority of utilities do not consider seismic loading and associated geotechnical hazards in the design of new or retrofitting existing transmission line structures. However, the study reviewed numerous case histories regarding the seismic performance of transmission line structures that documented the primary source of damage to transmission lines as a result of geotechnical-related seismic hazards.
Engineering & Operations Staff