## 2 Experimental Study of a Human Mass-Spring-Damping Model
### Identification of Pedestrian Dynamics Model Parameters
From the results in Figures 13a-16a, it can be seen that there is a significant negative correlation between body frequency and mass of high stature group whose walking frequencies are 1.5, 1.7, 1.9 and 2.1 Hz. From the results in Figures 13b-16b, it can be found that, when the walking frequency is 1.5, 1.7, 1.9 and 2.1 Hz, there is an obviously negative correlation between body frequency and the mass of short stature group from the results of the regression (\(p<~{}0.05\)). There is no significant correlation between the damping ratios of pedestrians and their body weight at all frequencies. It is advisable to take the average damping ratios of pedestrians in various walk frequency cases as a reference for the vibration serviceability evaluation of the structure. Figure 12: The influence of step frequency and stature on the parameters of the pedestrian MSD model: (**a**) mode frequency; and (**b**) damping ratio. In the field of structural vibration serviceability, few studies have been carried on to identify the parameters of walking human using SDOF MSD models. Representative studies in this field were reported by [PERSON] and [PERSON] [53], [PERSON] and [PERSON] [54] and [PERSON] et al. [43] respectively. By correlating the ground reaction force and the acceleration at the waist, [PERSON] and [PERSON] [53] obtained the dynamic parameters of a walking human. The frequency and damping ratio were suggested as 2.64 Hz and 0.55 if the human mass is assumed to be equal to 70 kg and walking frequency to be 1.8 Hz. Using a 3 DOF model to simulate the pedestrian-structure interaction in the vertical direction, [PERSON] and [PERSON] [54] suggested that the natural frequency and damping ratio of a walking human could be set as 2.75 Hz and 0.47 if the mass of the MSD modal was taken as 84% of the total body mass. With a comprehensive and unique set of human traffic-structure experimental data, [PERSON] et al. [43] obtained the ranges of frequency and damping ratio of the SDOF MSD as 2.75-3.00 Hz and 27.5-30%, respectively. Figure 14: Identification result of MSD model parameters of the subjects at pacing frequency of 1.7 Hz: (**a**) Group 1; and (**b**) Group 2. Note: \(f_{\rm G1}\) means the mode frequency of the high stature group, \(f_{\rm G2}\) denotes the mode frequency of the short stature group, \(\xi_{\rm G1}\) denotes the damping ratio of the short stature group. Figure 13: Identification result of MSD model parameters of the subjects at pacing frequency of 1.5 Hz: (**a**) Group 1; and (**b**) Group 2. Note: \(f_{\rm G1}\) means the mode frequency of the high stature group, \(f_{\rm G2}\) denotes the mode frequency of short stature group, \(\xi_{\rm G1}\) denotes the damping ratio of the high stature group and \(\xi_{\rm G2}\) denotes the damping ratio of the short stature group. The dynamic parameters suggested by the studies above are generally consistent with the findings of this study regarding the frequency and damping ratio, but the values in our study are slightly lower. This is due to the fact that, in our study, we picked the interaction between pedestrians and the floor slab as the research object. The three studies listed above, in contrast, all picked the interaction between pedestrians and bridges as the research object. By comparing the results of other studies, it can be assumed that the types of the structural system of the structure are not negligible when pedestrian-structure interactions were considered. The variation of pedestrian dynamic properties under different types of structural systems deserves to be explored in future research.