Probabilistic assessment of human response to footbridge vibration

Modern pedestrian bridges are becoming increasingly slender due to more demanding aesthetic requirements and increased strength of structural materials. As a consequence, they might suffer from excessive vibration under pedestrian-induced dynamic loading and therefore have their vibration serviceability compromised. For a reliable assessment of acceptability of vibrations to bridge users, it is necessary to define subjective vibration limits for pedestrians human vibration receivers who are moving across a vibrating surface, rather than being stationary. This paper aims to develop a methodology for defining vibration limits for walking humans. For this, substantial pedestrian traffic across a lively box girder footbridge was monitored. After interviewing 100 randomly chosen pedestrians about their subjective assessment of the vibration felt during the crossing significant variability in subjective rating of vibrations was observed. To account for this variability, the vibration limit for walking people was defined in a probabilistic sense. The limit defined allows for estimating the percentage of people who would complain about footbridge liveliness