Pedestrian Gait on Supporting Surface Exposed to Vertical Vibration

Growing demand for carbon reduction in construction, coupled with advances in high-strength materials, has encouraged the use of lightweight and slender structural forms in footbridge design. These environmental benefits usually come with a reduction in structural stiffness and increased susceptibility to walking-induced vibration. As a result, pedestrians often react to excessive deck vibrations by altering their gait. The strategies used for altering the gait are under researched and will be investigated in this paper. The paper examines the effects of vertical vibration on key spatiotemporal gait metrics: stride time, % stance phase, step frequency, and step width. Unlike previous work, this study evaluates the influence of vibration parameters: magnitude (0.5-2 m/s2), frequency (1.587-8 Hz), and exposure time (5, 15, 25 s), across ranges relevant to footbridge environments at preferred walking speeds. The association between parameters and gait metrics was statistically analysed using Spearman’s rank correlation. While walking speed was the dominant determinant of all gait metrics, vibration parameters exerted significant independent effects on gait organisation. Stride time was significantly negatively correlated with both walking speed and vibration magnitude. Stance phase was negatively associated with walking speed and vibration magnitude while positively associated with vibration frequency. Step frequency was positively associated with both walking speed and vibration magnitude. Step width increased significantly with vibration magnitude, while it decreased with walking speeds. The effect of exposure time was limited and observed to decrease stride time and step frequency at fast walking speed. These findings indicate that vibration magnitude is the primary driver of gait adaptation under vertical vibration, consistently shortened the gait cycle, reduced ground contact phase, and widened step width, potentially reflecting a protective postural response to mechanical instability.