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Development of dynamic load factors for human walking excitation for floor vibration design

Nguyen Huu Anh Tuan, Lythgo Noel, Gad Emad, Wilson John, Haritos Nicholas

International Journal of Applied Mechanics and Engineering

2022

Vol. 27, no. 3

103--114

This paper discusses the derivation of a set of dynamic load factors for calculation of walking response on the basis of measurements made during a biomechanics research carried out with young adults. Firstly, a quite large number of experimental data on single footstep force were collected. The single footstep forces were then superimposed to generate the force time history for a continuous walk. This was followed by the transformation of the resultant force to the frequency domain from which the dynamic load factors for the first ten harmonics of a pacing rate can be extracted. A statistical analysis was employed on the dynamic load factors to acquire their design values in terms of the 90-th or 95-th percentile. The waking force function recommended by various design guides and that developed in the paper were then used in a comprehensive finite element model to predict the vibration level of a building floor. Current design guides on floor vibration normally suggest using four harmonics in the walking force whereas load factors for ten harmonics were developed in this paper. The acceleration response of the floor was found to increase by 5-33% when walking harmonics beyond the fourth harmonic were considered. The inclusion of higher harmonics would therefore lead to a more conservative estimation of the floor response.

Vibrations of a low-frequency floor under various pedestrian loading scenarios

Nguyen Huu Anh Tuan

Architecture Civil Engineering Environment

2021

Vol. 14, no. 4

105--114

Contemporary floor vibration guidelines limit the discussion of walking-induced vibrations to single-pedestrian loading scenario. Nevertheless, the inclusion of more than one pedestrian in the vibration evaluation would result in a more realistic range of floor responses. In this paper, an attempt was made to experimentally and numerically investigate the combined effect of two persons walking simultaneously on an actual building floor. The floor fundamental frequency and damping ratio were obtained from physical heel drop tests and the footfall response was measured in a series of walking tests. A finite element model was created for prediction of floor responses under different walking scenarios. A probabilistic prediction was also performed where random variations in pacing rates, body weights and arrival times of the pedestrians were considered in a large number of Monte Carlo simulations. It was showed that the response due to a single person with resonant step frequency can be greater than that due to two persons walking at off-resonant pacing rates. However, the resonant response induced by two pedestrians can be 1.29-1.38 times greater than that caused by a pedestrian.