STOCHASTIC DYNAMICS OF A GUYED MAST UNDER WIND LOAD

JORGE SEBASTIAN BALLABEN; MARTA ROSALES; RUBENS SAMPAIO

Lagos

Congreso; International Conference on Structural Engineering Dynamics; 2015

Detailed studies of guyed structures under natural actions as wind or earthquake, are not frequent despite the potential of adverse impact, e.g. fatigue of structural members or affected quality of the transmission in communication guyed towers. In this work, the stochastic dynamics of a guyed mast is analyzed under wind load action. The simplified structural model consists of a beam-column model accounting for the second order effect due to axial loads and one guy which is represented by a non-linear extensible cable. The resulting governing system is discretized using finite elements and a reduced order model is afterwards constructed using vibration modes as a basis. The model is stochastic due to the load and some structural properties uncertainties. The wind load is calculated from the wind velocity field by means of the Spectral Representation Method. Since nonlinear structures show special sensitivity to dynamic loads, the reference nominal wind velocity (suggested in the standards) is also considered as a stochastic parameter. As the guy pretension is a significant parameter in the behavior of guyed structures, its variation is a relevant issue. Furthermore, the bending stiffness can vary due structure reinforcements. Since it is not easy to foresee their behavior, an uncertainty quantification study appears necessary. After performing Monte Carlo simulations, the probability distribution functions (PDF) of the results are observed accounting for each parameter (guy tension, bending stiffness and wind nominal velocity) separately. Also, parameters combinations are considered. The studied variables exhibit very different types of influence on the statistics of the dynamic response.