To meet the basic requirements of long spans, steel footbridges are generally lightweight structures with low stiffness. Moreover, current trends in innovative structural design have led to more vibration problems related to resonance or quasi-resonance of footbridge structures at typical pedestrian walking frequencies. The present authors apply a feasible methodology to assess the vibration performance of footbridges based on an equivalent beam model developed from a detailed finite-element model and experimental measurements. Free- and induced-vibration tests are performed on a long-span inverted-queen-post-truss steel footbridge located in Rio de Janeiro, which exhibits vibration problems. Pedestrian walking simulations are performed with the simplified footbridge model using a typical dynamic load given from a Fourier series, as well as with a biodynamical formulation that considers human–structure interactions. The equivalent beam model provides a practical means of investigating corrective intervention strategies for the problem of excessive footbridge vibration using tuned mass dampers, and allows the in-service footbridge performance to be assessed based on current standards and design guidelines.
ResumoO artigo apresenta a análise da interação solo-estrutura de uma construção que revelou, ao longo dos anos, comportamento inadequado de suas fundações. São resumidas análises anteriores de Rosa (2005), incluindo a interação solo-estrutura na previsão dos recalques. Essa nova análise considera, também, a influência das alvenarias na interação. Os recalques distorcionais previstos são analisados em conformidade com os danos, documentados em vários momentos da vida útil da edificação. O modelo de Kelvin foi utilizado para representar o comportamento do solo com o tempo. Verificou-se que, mesmo com as simplificações adotadas, justificadas no artigo, os resultados da análise numérica foram capazes de reproduzir a extensão dos danos, assim como sua localização espacial. Os resultados mostram a importância de uma concepção de projeto de fundações mais realista, contemplando a interação solo-estrutura.
Palavras-chave:Interação solo-estrutura, danos estruturais, recalques distorcionais.
AbstractAn analysis of soil-structure interaction of a construction with unsatisfactory foundation behavior along time is presented. Previous analyses by Rosa (2005) are briefly described considering soil x structure interaction in predicting foundation settlement. In addition, a new analysis is now presented, including the influence of the masonry in the soil-structure interaction. The predicted distortional settlements are analyzed in conformity with the observed damages documented at various moments of the construction lifetime. Kelvin's model was employed to represent the soil behavior along time. Notwithstanding the simplifications adopted and justified in the article, the results of the numerical analysis were able to reproduce the extent and spatial location of the damages. Such results show the relevance of a more realistic foundation analysis involving soil x structure interaction.
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