Parametric Study of the Dynamic Along-Wind Response of a Guyed Tower

As wireless communications spread, there is an increasing demand for antenna supportingstructures. Lattice towers are commonly used systems, either self-supported or guyed. The latter arechosen for economical reasons when there is enough space for their location. Radio and television em-ploy structures that range between 100 and 600 m and communication towers for mobile phones arearound 60 m though higher structures are also constructed. For large heights, guyed masts are indi-cated. However, it depends on the customer preferences, suppliers, budget and location. Generally,self-supported structures are preferred in urban areas and guyed masts in the countryside. Nowadays thedemand for more accurate and reliable communication systems poses higher structural demands sincethe signal technology sometimes requires of very small motions of the supporting structures to achieve ahigh quality transmission. The design of these structures is, in general, carried out following the standardcodes and simplified models. The dynamic actions, as wind and earthquakes, are not addressed in detailwith exception of special cases, despite the large potential of adverse impact. Guyed structures stiffnessare highly dependent on the guys tension. The influence of this parameter is relevant to the dynamicresponse. Also, the mast stiffness and damping are variables of interest. In this work, the dynamic re-sponse of a communication lattice guyed tower is analyzed under wind loads and the degree of influenceof the mentioned parameters is assessedLaboratorio de Capa Límite y Fluidodinámica AmbientalGrupo Fluidodinámica Computaciona

Parametric Study of the Dynamic Along-Wind Response of a Guyed Tower

As wireless communications spread, there is an increasing demand for antenna supportingstructures. Lattice towers are commonly used systems, either self-supported or guyed. The latter arechosen for economical reasons when there is enough space for their location. Radio and television em-ploy structures that range between 100 and 600 m and communication towers for mobile phones arearound 60 m though higher structures are also constructed. For large heights, guyed masts are indi-cated. However, it depends on the customer preferences, suppliers, budget and location. Generally,self-supported structures are preferred in urban areas and guyed masts in the countryside. Nowadays thedemand for more accurate and reliable communication systems poses higher structural demands sincethe signal technology sometimes requires of very small motions of the supporting structures to achieve ahigh quality transmission. The design of these structures is, in general, carried out following the standardcodes and simplified models. The dynamic actions, as wind and earthquakes, are not addressed in detailwith exception of special cases, despite the large potential of adverse impact. Guyed structures stiffnessare highly dependent on the guys tension. The influence of this parameter is relevant to the dynamicresponse. Also, the mast stiffness and damping are variables of interest. In this work, the dynamic re-sponse of a communication lattice guyed tower is analyzed under wind loads and the degree of influenceof the mentioned parameters is assessedLaboratorio de Capa Límite y Fluidodinámica AmbientalGrupo Fluidodinámica Computaciona

Modal Features and Dynamic Behavior of a Nonlinear 3D Guyed Mast with Uncertain Guys Pretension

The study of the nonlinear dynamic characteristics and 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. Starting from the energy formulation of beams and nonlinear cables, the continuous equations are discretized using finite element techniques, considering Hermite elements for the mast (Bernoulli beam theory) and quadratic elements for the nonlinear guys. Also, the second order effect due to the axial loads on the mast is taken into account. An ad hoc software, developed by the first author, is employed here to explore natural frequencies and modes of the structure considering the uncertainty propagation of the stochastic guys pretension. Since the guys design value can be modified at the construction stage and more, 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). 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. The results here presented (natural frequencies and modes) obtained through an uncertainty quantification analysis, improve the understanding of the real dynamic properties and behavior of slender and flexible guyed structures.Publicado en: Mecánica Computacional vol. XXXV, no. 21Facultad de Ingenierí

Modal Features and Dynamic Behavior of a Nonlinear 3D Guyed Mast with Uncertain Guys Pretension

The study of the nonlinear dynamic characteristics and 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. Starting from the energy formulation of beams and nonlinear cables, the continuous equations are discretized using finite element techniques, considering Hermite elements for the mast (Bernoulli beam theory) and quadratic elements for the nonlinear guys. Also, the second order effect due to the axial loads on the mast is taken into account. An ad hoc software, developed by the first author, is employed here to explore natural frequencies and modes of the structure considering the uncertainty propagation of the stochastic guys pretension. Since the guys design value can be modified at the construction stage and more, 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). 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. The results here presented (natural frequencies and modes) obtained through an uncertainty quantification analysis, improve the understanding of the real dynamic properties and behavior of slender and flexible guyed structures.Publicado en: Mecánica Computacional vol. XXXV, no. 21Facultad de Ingenierí

Modal Features and Dynamic Behavior of a Nonlinear 3D Guyed Mast with Uncertain Guys Pretension

The study of the nonlinear dynamic characteristics and 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. Starting from the energy formulation of beams and nonlinear cables, the continuous equations are discretized using finite element techniques, considering Hermite elements for the mast (Bernoulli beam theory) and quadratic elements for the nonlinear guys. Also, the second order effect due to the axial loads on the mast is taken into account. An ad hoc software, developed by the first author, is employed here to explore natural frequencies and modes of the structure considering the uncertainty propagation of the stochastic guys pretension. Since the guys design value can be modified at the construction stage and more, 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). 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. The results here presented (natural frequencies and modes) obtained through an uncertainty quantification analysis, improve the understanding of the real dynamic properties and behavior of slender and flexible guyed structures.Publicado en: Mecánica Computacional vol. XXXV, no. 21Facultad de Ingenierí