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DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
NONLINEAR DYNAMICS OF A THREE-DIMENSIONAL GUYED MAST WITH UNCERTAIN GUYS PRETENSION
Submission Author:
Marta Rosales , Buenos Aires , Argentina
Co-Authors:
Jorge Sebastian Ballaben, Marta Rosales, Rubens Sampaio
Presenter: Marta Rosales
doi://10.26678/ABCM.DINAME2017.DIN17-0172
Abstract
The study of the nonlinear dynamic response of a guyed mast considering the uncertainty of the guys pretension is reported in this work. A computational model is constructed with the mast represented by an equivalent beam-column and the three guys at one level, by cables with an initial pretension and only having tensile capacity. The system of partial differential equations is discretized using the finite element method considering hermite elements for the mast (Bernoulli beam theory) and nonlinear cable elements for the guys . Also, the second order effect due to the axial loads on the mast is taken into account. A lateral dynamic load is applied on the mast. An ad hoc software developed by the first author is employed to solve the problem. Once the deterministic problem is stated, an uncertainty quantification is carried out. In this case, the stochastic variable is the pretension. Since the design value can be modified at the construction stage and during the service life , the pretension force is modeled as a random variable with a probability density function (PDF) derived from the Principle of Maximum Entropy (PME). First, the case in which all the cables have the same pretension (though stochastic) is solved. However, a situation in which the cables do not have the same value of pretension is possible due to eventual discrepancies in the installation. Thus, a small random error is introduced to make the guys tensions different among them. The radial symmetry is thus lost. The model herein presented contributes to attain a more realistic description of the structure, mainly regarding the three-dimensional representation and the sensibility to the variability of the guys pretensions.
Keywords
guyed mast, nonlinear dynamics, uncertain pretension, propagation of uncertainties
