Parametric exploration of a simple model of human jumping on an oscillating structure

Research output: Contribution to journalArticle (Academic Journal)peer-review

Abstract

Lightweight and long-span civil structures, such as grandstand tiers, are susceptible to vertical vibrations due to jumping or bobbing of human spectators. After a careful review of experimental evidence, including new data, a simple mathematical model is investigated in order to characterise human-structure interactions observed during human rhythmic jumping on a perceptibly moving surface. A passive mass-spring-damper is used to model a human jumper whilst subjected to an input structural oscillation. The coupled system is modelled as a piecewise-smooth contact dynamics problem allowing for the loss of contact during rhythmic jumping. Parametric sweeps are interpreted using methods from non-linear dynamical systems theory, including bifurcation analysis and the use of Poincaré maps. Hysteresis and coexistence of qualitatively different stable periodic motions over a broad range of parameter values of the system are observed. The presence of such coexisting non-intuitive motions is verified by preliminary experimental results that indicate period-doubled jumping behaviour (a repeating sequence of large-jump-small-jump) of test subjects both above and below a structure’s natural frequency. At large amplitudes of structural motion, the model shows that the behaviour can become chaotic. This provides an explanation for experimental findings that it is difficult to jump periodically around the natural frequency of a supporting structure. The simple model provides a detailed map of where different motions occur in parameter space, which should be amenable to further experimental validation.
Original languageEnglish
Article number116227
Number of pages18
JournalJournal of Sound and Vibration
Volume509
Early online date23 May 2021
DOIs
Publication statusE-pub ahead of print - 23 May 2021

Bibliographical note

Funding Information:
Rory E. White is funded by a EPSRC DTP scholarship.

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

  • human-structure interaction
  • human loading
  • non-linear structural dynamics

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