Example of bispectral analysis of a transmission line pylon

Abstract

It is common practice to tackle buffeting analysis by means of spectral analysis, assuming a Gaussian context. However, natural actions, as wind, or wave loading, might sometimes show important non-Gaussian behaviour. This is known to have an important impact on the extreme values of such random processes. In this context, a non-Gaussian bispectral turbulent wind analysis has been conducted on a transmission line pylon model. The non-Gaussian nature of the wind load is the result of the adoption of a nonlinear polynomial wind model applied to the Gaussian wind turbulent velocity components. Results of a stochastic dynamic analysis are compared with respect to their Gaussian counterpart, as well as to the Eurocode approach based on the equivalent static loads, which was also object of comparison of engineers in the original computation with respect to turbulent wind dynamic analysis. Importance of non-Gaussian nature of wind loading is highlighted, and considerations on why and when it should not be underestimated are discussed.