Comparison of frequency- and time-domain analyses for guyed masts in turbulent winds

Both frequency- and time-domain methods have been employed in the dynamic analysis of guyed telecommunication masts subjected to turbulent winds. Although the probabilistic frequency-domain approach offers some advantages in terms of its relative ease of implementation and in the statistical reliability of wind load descriptions, the deterministic time-domain method permits a more realistic treatment of system nonlinearities. In this study, a numerical investigation was undertaken to compare frequency- and time-domain dynamic response predictions for a selected guyed mast in gusty winds. Two different analysis techniques were employed, with the frequency-domain calculations performed using response influence lines and the time-domain analyses carried out using a stiffness-based finite element model. Good agreement was observed in root-mean-square and peak dynamic response estimates after compensation was included for differences in turbulence intensity levels assumed in the two models. In general, natural frequencies and mode shapes were also similar.Key words: guyed mast, dynamic analysis, wind, turbulence, nonlinear behaviour, finite element analysis, cables, frequency domain, time domain.