SELF-SUPPORTING LATTICE TOWER UNDER DYNAMIC WIND LOADS

Resumo

The difficulty to determine time-variant loadings, such as wind loading, stands out among

the structural engineering challenges. For example, the wind is the preponderant action in a self-
supporting lattice tower, and its wrong estimation can lead to unwanted vibration and displacements in

the structure. Those structures are usually designed with a simplified dynamic effect, in which the
wind is considered as a static load, increasing its value by dynamic coefficients proposed in standard
codes. However, this simplification can easily lead an improper design. Although there are various
non-standard methods for the determination of the time variant loading of the wind in order to achieve

a more accurate and reliable analysis, this work focuses on the Synthetic Wind Method, that is a non-
deterministic process using the Monte Carlo simulation in order to obtain wind loadings by

superposition of harmonic functions with random phase angles. This work provides a dynamic
analysis of a self-supporting lattice tower using the Synthetic Wind Method with different wind
spectra (Davenport, slightly modified Davenport, Harris and Kaimal). A comparison between the
dynamic and the static response obtained by the Brazilian code NBR 6123/1988 – Forces due to wind
on buildings is also made. The structure calculated with the original and the slightly modified
Davenport spectra have given similar and the largest displacement responses. Whereas the Harris
power spectral density proved to be the least conservative for this study.