Effects of wind-induced vibrations in tall buildings on cognitive work performance, comfort, and wellbeing of the occupants

Tall buildings inherently have low natural frequencies, excitable by wind loading through buffeting and vortex shedding. Such vibrations can cause discomfort or even fear in the occupants which is a design failure from vibration serviceability standpoint. Current wind-induced vibration serviceability guidelines such as ISO10137-2007, have proposed their acceptability criteria based on human perception of vibrations. However, recent studies suggest that such perception thresholds may not be an appropriate measure of vibration acceptability. Rather, more direct factors such as influence on work (both cognitive and physical) performance, health and wellbeing, and the emergence of mild motion sickness (sopite syndrome), should be used to assess 'acceptability'. This study provides experimental evidence of the effects of wind-induced vibrations on cognitive work performance, comfort, and wellbeing of the occupants. The state-of-the-art motion simulator facility, located at the University of Bath (VSimulator) was used to simulate bidirectional random vibrations, typical of tall building response due to wind loading. Under fully controlled conditions, research participants were exposed to six different motion conditions, as a cross-product of two frequencies and three peak accelerations, five of which were deemed acceptable for office buildings according to ISO-10137. Both objective and subjective psychological measurements were carried out to evaluate work performance, comfort, and wellbeing of participants subjected to these different motion characteristics. The results showed that both peak acceleration and frequency of motion had adverse effects on work performance, comfort and wellbeing of participants and showed evidence of the onset of sopite syndrome symptoms during even relatively short (~2 hour) exposures. It was concluded that even for motion conditions with peak acceleration magnitudes below the threshold of conscious perception, there were negative consequences, especially as exposure to such motions caused participants to experience sopite syndrome. The data here suggests that buildings constructed to current standards might lead to negative consequences for wellbeing and work performance even when people are not consciously aware of any motion. Current serviceability criteria might be insufficient to address acceptable levels of wind-induced vibrations in tall buildings and future design criteria could be based on how vibrations affect health, wellbeing and performance rather than simply on the perceptibility of vibrations.