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Structural Monitoring and Maintenance Volume 9, Number 2, June 2022 , pages 201-220 DOI: https://doi.org/10.12989/smm.2022.9.2.201 |
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Conditions to avoid synchronization effects in lateral vibration of footbridges |
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Alexandre R. Andrade, Roberto L. Pimentel, Simplício A. da Silva and Cícero da R. Souto
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| Abstract | ||
| Lateral vibrations of footbridges may induce synchronization between pedestrians and structure itself, resulting in amplification of such vibrations, a phenomenon identified by lock-in. However, investigations about accelerations and frequencies of the structural movement that are related to the occurrence of synchronization are still incipient. The aim of this paper is to investigate conditions that could lead to avoidance of synchronization among pedestrians themselves and footbridge, expressed in terms of peak acceleration. The focus is on the low acceleration range, employed in some guidelines as a criterion to avoid synchronization. An experimental campaign was carried out, employing a prototype footbridge that was set into oscillatory motion through a pneumatic exciter controlled by a fuzzy system, with controlled frequency and amplitude. Test subjects were then asked to cross the oscillating structure, and accelerations were simultaneously recorded at the structure and at the subject's waist. Pattern and phase differences between these signals were analysed. The results showed that test subjects tended to keep their walking patterns without synchronization induced by the vibration of the structure, for structural peak acceleration values up to 0.18 m/s2, when frequencies of oscillation were around 0.8 to 0.9 Hz. On the other hand, for frequencies of oscillation below 0.7 Hz, structural peak accelerations up to 0.30 m/s2 did not induce synchronization. | ||
| Key Words | ||
| footbridge; lock-in; pedestrian; synchronization; vibration | ||
| Address | ||
| Alexandre R. Andrade: Unidade Acadêmica de Controles e Processos Industriais, Instituto Federal da Paraíba, Campus João Pessoa, Av. Primeiro de Maio, 720, João Pessoa 58015-435, Brazil Roberto L. Pimentel: Departamento de Engenharia Civil e Ambiental, Universidade Federal da Paraíba, Cidade Universitária s/n, João Pessoa 58051-900, Brazil Simplício A. da Silva, Cícero da R. Souto: Departamento de Engenharia Elétrica, Universidade Federal da Paraíba, Cidade Universitária s/n, João Pessoa 58051-900, Brazil | ||
