Estudo do comportamento dinâmico de passarelas ´devido ao caminhar de pedestres

• Autor(a) principal: Figueiredo, Fábio Pereira
• Data de Publicação: 2005
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/11519
• topic: Vibration; Footbridges; Dynamic Analysis; Steel Structures; Composite Structures; Computational Modeling; Vibrações; Passarelas; Análise Dinâmica; Estruturas de Aço; Pisos Mistos; Modelagem Computacional; CNPQ::ENGENHARIAS::ENGENHARIA CIVIL

Nowadays footbridges have been designed more and more slender due to the progress of the technology and researches of new materials. A direct consequence of that is the considerable increase of vibration problems. In the particular case of footbridges this phenomenon happens when the fundamental frequency of the structure is the same or near the frequency of the pedestrian's step. Human activities as walking, running or jumping produces dynamic forces and, as a consequence, a vibration response, that can disturb and alarm the people that are using the structure. As the primary purpose of the footbridges is the transport of pedestrians, they need to be safe and to present a behavior that doesn't offer discomfort to the users. In this case, the present study was developed to give a contribution to the evaluation of the dynamic response of pedestrian's footbridges, mainly, in terms of human comfort. Thus, several loading models are developed to represent the pedestrians walking on the structure. This study was carried out based on a more realistic loading model developed to incorporate the transient impact of the heel due to walking. In this loading model, the movement of legs that cause an ascent and descent of the effective mass of the human body in each passing was considered and the position of the dynamical loading is changed according to the individual position and the generated time function, corresponding to the excitation induced by people walking, has a space and time description. The analysis of several distinct projects from footbridges was accomplished in an extensive study of cases, where the dynamic responses of those structures were investigated. In a subsequent phase, structural characteristics and dynamics were evaluated through a parametric study. The obtained results, in terms of the vertical peak accelerations and rms accelerations were compared with designs criteria. Through the analytical and numerical results reached it was possible to demonstrate the importance of the modelling of the loading generated during a walking and as those results are fundamental for a good evaluation of the dynamic response of the structures. The results obtained along the study indicate, clearly, that the structural designers should be alerted for important distortions that it happen when the design codes are used without the due care. Another important aspect is the fact that in several analyzed footbridges is observed that the criteria of human comfort are not satisfied, demonstrating the importance of the dynamic effects due to the human activities in the analysis of this problem type.