Avaliação da resposta estrutural dinâmica de edifícios submetidos à ação do vento com base na comparação entre metodologias distintas para estimativa das acelerações

Abstract

Nowadays, the design and construction of tall and slender buildings to attend the demand of population growth; and, as well as, the reduction of free spaces available in urban areas, have resulted in relevant structural problems related to excessive vibrations and human discomfort caused by the dynamic characteristics of the wind loadings. The use of experimental tests in wind tunnels is still the most reliable way of evaluating the dynamic structural response of buildings. However, such methodology may lead to delays; and, furthermore, cost growth in the design phase of a building. A viable alternative to the use of wind tunnels is the use of simplified methodologies to estimate the dynamic response. Within this context, stand out the normative methods that are generally based on the Davenport Gust Factor Method, the Database Assisted Methods, which consider the data obtained in tests performed in wind tunnels, considering standardized geometries for the calculation of the responses, and the Spectral Representation Method, used to generate the wind load considering its dynamic characteristics. Thus, in order to compare the mentioned methodologies, this master's thesis considers four models of buildings, namely: two simplified models, the first with dimensions of 40 mx 40 mx 200 m and second with dimensions of 30 mx 45 mx 180 m, both with characteristics provided in articles pertinent to the subject addressed in this work; in addition to two structural models of real buildings, the first building in reinforced concrete with dimensions of 20,24 mx 29,19 m and total height of the order of 70 m and the second building in steel-concrete composite structure with dimensions of 32 mx 45 m and height total of 172,80 m. The comparisons were made based on the maximum values of the longitudinal and transverse accelerations, respectively, calculated at the top of the buildings with the use of all methods studied. Regarding real buildings, an evaluation of human comfort was carried out. Among the standards and methods considered, the American design standard and the Spectral Representation Method presented values of the along-wind accelerations closer to those obtained in the experimental tests carried out in wind tunnels. Considering the values of the across-wind accelerations, none of the standards presented satisfactory results. However, in spite of the differences found, this research clearly shows the importance of considering the across-wind acceleration, which, in the majority of cases, presented a higher value throughout the analyzes, being, therefore, a determining factor for the human comfort assessment.