Verificação de dimensionamento dinâmico de estrutura em aço: Estudo de caso para uma passarela sobre linha férrea

Abstract

With the function of facilitating the crossing of obstacles such as urban roads, dry valleys or watercourses, walkways are a type of structure that can present challenges in its design. As more resistant materials are used, the use of structural elements with greater slenderness is allowed, which results in the manifestation of behaviors that previously could be neglected, but which now become relevant, such as excessive vibrations that cause great discomfort to users. This work analyzed the dynamic behavior of a walkway made with structural steel elements using the SAP2000 program. For the dynamic analysis of the structure, the natural frequency modes found in the numerical modeling were considered and from their indications it was possible to carry out a check to know if the structure to be designed also needs a more specific analysis in relation to the dynamic effect, which is often neglected in calculations. From the data obtained by the computational analysis, the frequency values of the footbridge flexion mode were compared with the normative limit of 3Hz of the ABNT NBR8800:2008, a limit established so that there is no resonance of the structure with human walking, and the its period values, in lateral displacement mode, with the limit of 1s of ABNT 6123:1988, limit for which the floating portion of efforts needs to be considered. Thus, the data show that the analyzed structure meets these criteria, being verified in relation to the dynamic effects.