Comparative Analysis of Static and Dynamic Methods in Metallic Tower Design

Resumo

This paper presents the design of a telecommunications tower, addressing various structural analysis methods: static, simplified dynamic, discrete dynamic, and modal analysis, as defined in ABNT NBR 6123:2023, for wind loads acting on the structure. The study focuses on a tower located in the region of Pato Branco, in the state of Paraná (Brazil), with a height of 50 meters, constructed with tubular profiles. The calculation procedure was carried out using ANSYS 2018 R1 software, incorporating the mentioned methods through finite element analysis. While the static analysis does not consider dynamic effects, the dynamic methods provide results with different periods, reflecting the response of the structure. The aim of this study was to determine which method should be adopted, taking into account the design requirements for axial tension and compression. Evaluating the safety margins obtained for the structural elements, it was found that up to 20 meters in height, the static analysis presents higher loads; however, above this height, the dynamic effects of the wind are predominant. This result demonstrates the importance of dynamic wind analysis for towers over 20 meters in height. Furthermore, it is possible to verify that the simplified model using the first period of the structure according to ABNT NBR 6123:2023 is more conservative than using the period and frequencies resulting from a modal analysis by numerical finite element modeling.