Vibrações não lineares de colunas esbeltas parcialmente enterradas

• Autor(a) principal: Pires Filho, Leyser Pacheco
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/9564
• topic: Colunas parcialmente enterradas; Base elástica; Winkler; Pasternack; Vibrações não lineares; Partially embedded columns; Elastic base; Winkler; Pasternack; Nonlinear vibrations; ESTRUTURAS::MECANICA DAS ESTRUTURAS

In this work the nonlinear vibrations of partially embedded slender columns subjected to axial and lateral loads are studied. The thin column is modelled by the nonlinear Euler-Bernoulli theory e the soil behavior is described by two models: the Winkler model, which considers the load proportional to the column deflection, and the Pasternack model, which takes into account two different stiffness parameters to describe the elastic base. The equations of motion of the column are derived from the energy functionals through the application of the Rayleigh-Ritz method along with the Hamilton principle and, afterwards, are solved by the convenient method for each analysis. It is accomplished a convergence study for the natural frequencies of the column in order to assess qualitatively the response from each elastic base model. The post-critical and amplitude- frequency relationship curves are obtained, allowing to understand how the system stiffness varies with the increase of axial load and frequency amplitude, respectively. From the solution of the equations of motion by the forth order Runge-Kutta method, the resonance curves, the parametric instability and escape boundaries, the bifurcation diagrams and associated phase portraits are obtained, enabling identifying in what ways the elastic base parameters from each model affect the nonlinear vibrations of the column partially embedded. Lastly, it is presented a brief study about the dynamic amplification in the column response when the lateral load is applied as an impact.