Instabilidade dinâmica de arcos tri-articulados

• Autor(a) principal: Braga, Igor Cézar Silva
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• dARK ID: ark:/38995/00130000080dw
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/7722
• topic: Arcos tri-articulados; Instabilidade dinâmica; Análise paramétrica; Tri-articulated archés; Dynamic instability; Parametric analysis; ENGENHARIA CIVIL::GEOTECNICA

Arches are structural elements of curvilinear form transmitting normal efforts of simple compression and with wide applicability in civil engineering, being used in bridges, domes, soccer stadiums and so on. Therefore, studies that involve physical and geometric parameters to analyze the behavior of arches are necessary. This work aims to study the static and dynamic instability of tri-articulated discrete arcs, with axial and rotational rigidities the supports and under the action of a time dependent load. The arche is evaluated is a discrete and continuous system. The discrete system consists of three degrees of freedom that describe the vertical displacement and two horizontal displacements; the continuous system composed of two degrees of freedom, with an axial displacement and another in the direction radial. For the discrete system a parametric analysis was performed by varying the axial stiffness and rotational rigidities in the supports, besides the height of the arch, considering first the post-critical path study, with the influence of the parametric variation in the obtained results and the effect of the symmetry breaking in the instability by point limit or snap through, with the appearance of dynamic jumps. The natural frequency analysis is a function of the height/span ratio and the rigidities in the boundary conditions of the structures. The dynamic analysis was initiated through the instability boundaries, where it is observed how the displacements were established according to the parameters adopted, the obtained answers were proved by time responses, bifurcation diagrams and attraction basins, noting the influence of these factors in the dynamic behavior of the discrete arch. The analysis of the continuous system was established in the variation of the modified slenderness of the flexibility in the supports, observing the interference of the parameters in the post-critical path in general and in the load of the axial compression. With the asymmetry in the flexibility of the supports, the loops coming from the dynamic jumps arise.