Earthquakes

Poles ‘n’ Wires does not have any allowance for earthquake/seismic loading. The following may give some guidance to these loadings.

AS7000:2016 in Appendix C (Informative) says:

In general, pole and tower structures have proven not to be susceptible to damage from earthquake shaking motions (C4.2)

Wind loadings are usually the main determining factor in the design of overhead line towers, however seismic loads may lead to additional loading forces that should be considered in known very active seismic zones. (C4.1)

…pole structures supporting heavy equipment (ie transformers)… should be designed to resist earthquake loads (C4.2)

Guide to Improved Earthquake Performance of Electric Power Systems (published by National Institute of Standards and Technology, Gaithersburg, MD, USA) says:

While there has been significant damage to distribution systems, mitigation and retrofitting does not appear justified, with the possible exception of anchoring or restraining distribution transformers (6.2.2) The only observation from past earthquakes to improve the performance of the distribution system is to anchor distribution transformers as they are installed (6.2.4)

AS7000 sect C4.1 says to refer to AS1170.4 for appropriate general design provisions. AS1170.4 [Structural design action—earthquake actions in Australia] sect 2.2 says that Importance level 1 structures are not required to be designed to the Standard’s requirements. AS1170.0 gives the definition of importance levels in section F2—importance level 1 structures are “minor structures (failure not like to endanger human life)”

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