Effect of tornadoes on electrical power lines has been discussed by Sébastien Langlois in his M.Eng. thesis : “Design of Overhead Transmission Lines subject to Localized High Intensity Wind”. McGill University, Montreal, QC, Canada, 2007 (available on-line on the “Theses Canada” portal). Work presents various national and international standards (ASCE, Cigré, IEC etc.), historical cases, as well as models for numerical simulation.
In the review paper by Spak & al. (January 2013) on cable bending mechanical models, one class of models was not specifically mentioned, in which authors attempt to take into account the tangential elasticity at points of contact between cable layers. There are at least two noteworthy contributions:
Cable and Overhead Electrical Conductor mechanical models are closely related. This can be seen from a recent review (January 2013) by Spak, K., Agnes, G. and Inman, D. : Cable Modeling and Internal Damping Developments, in the ASME journal Applied Mechanics Reviews, Vol. 65. The 18 pages paper, with its 86 references, has an interesting section on bending stiffness, with a rather (comparatively) extensive presentation of Papailiou’s stick-slip model. Use of the Coulomb spring-slider model for internal damping prediction is also presented.
In elementary mechanics textbooks, power lines are generally given as a typical example of a so-called “flexible cable”. However, in the design of these critical elements of a power grid it is often necessary to take into account the conductor bending stiffness, or flexural rigidity. While relatively low compared with a bar having an equivalent solid cross-section, it does have some influence on a conductor response to wind excitation, in particular from the fatigue strength point of view.
Mechanics of overhead electrical conductors under wind excitation is a complex problem . It is described in detail in the following book:
EPRI Transmission Line Reference Book: Wind-Induced Conductor Motion. Second Edition. EPRI. Palo Alto, CA. 2009. 1018554.
EPRI : Electric Power Research Institute.