Synchronisation of Humans Jumping on a Flexible Structure

Modern lightweight structures can be more prone to potentially destructive vibration. The collapses of the NEC Goffert Stadium (2021) and Furiani Stadium (1992) highlight the vulnerability of slender structural designs to human-induced vibrations, with synchronised jumping being the root cause of both incidents. Whilst synchronicity among humans influencing the force experienced by a structure is known about, the role of human-structure interaction as a catalyst for this synchronisation remains largely unexplored. This paper investigates systems of humans jumping on flexible structures, to determine if their interaction can result in synchronisation of the humans via the structure. A three degree-of-freedom synchronisation model, incorporating a novel actuation method, was developed and numerically investigated, demonstrating behaviour that aligns with previous experimental findings. It was found that, given comparable physiologies, the jumpers can become synchronised with either phase-matched or anti-phase oscillations, with a variety of oscillation periods and even chaotic dynamics. Furthermore, the relative physiological parameters of the two humans were explored to understand their impact on the synchronisation. Whilst differing physiological parameters of human jumping affect the phase and amplitudes of the resultant dynamics, there is still an overall tendency for them to synchronise. This behaviour was found to scale to larger systems of N jumping humans, suggesting that design codes for dynamic human jumping may be inadequate for structures that can move significantly, as they fail to account for the additional synchronicity generated through human-structure interaction.