Development of Dynamic Load Factors for Human Walking Excitation for Floor Vibration Design

Abstract

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.

Floor vibrations and rectification

“…where P is the walker's weight; fp is the step frequency; i and i are the dynamic coefficient (Fourier coefficient) and phase lag for the i-th harmonic component of the walking excitation; and n is the 2 as measured using a pressure plate [6]. The design static weight of a walker P is usually assumed to be in the general range of 700 N to 800 N but should be selected to reflect the typical weight of users which could be higher.…”

“…The recommended number of harmonics and associated coefficients vary in published guidelines as demonstrated in Table 1. In a recent study by the authors [6] a large number of experimental data on single footstep force was obtained from a biomechanics research. The characteristic values in terms of 90 th percentile and 95 th percentile dynamic load factors have been proposed for the first ten walking harmonics.…”

Vibration Performance of Flat Plate Concrete Floors With Codified Minimum Thickness

“…Supriyadi found that the maximum vertical displacement of an auditorium floor doubled as a result of a group of persons dancing in unison in response to live music [6]. Walking is a common type of dynamic loading that needs to be considered when designing a floor [7]. In fact, there have been reports of disturbing floor vibrations caused by normal walking excitation [3].…”