## 3 Dynamic Characteristics and Comfort Analysis
### Human-Induced Vibration Analysis  
The monozail system vehicle acts vertically on the track subsystem. With the track structure's refined fabrication and the curved sections' speed limit requirements, the track will not normally generate excessive vibration during vehicle driving. Relevant research [6,38] has shown that the monozail system vehicles' running stability and riding comfort are good. When pedestrians walk on the evacuation platform, the crowd load  
Figure 4: Time history and frequency domain signal of acceleration by the residual vibration method. Figure 5: Mode and frequency. acts eccentrically on the main structure of the MTTS. The lateral stiffness of the MTTS is relatively weak, and the designers cannot ignore the lateral vibration caused by the crowd load. Therefore, this paper only studied the lateral response of human-induced vibration. Three people (A, B, and C) participated in the human-induced vibration test. The test conditions were divided into multi-person and multi-frequency walking to study the impact of the number of excitations and frequency on the structural response. A stopwatch timer controlled the excitation frequency. The acquisition time of each condition was 10 s. At the same time, 10-person excitation conditions were simulated. Table 2 shows the specific condition information, and the walking route is shown in Figure 3d. The field test is shown in Figure 8.  
When people generally walk on the evacuation platform, there is a slight lateral amplitude on the top of the column. The measured lateral amplitude on the top of a column is shown in Figure 9. It can be seen from the analysis that when the vibration was excited at  
Figure 6: Stability index under full load operation. Figure 7: Comfort index under full load operation. the frequency of 2 Hz, the lateral amplitude of the column top was the measured maximum value in all cases, which is consistent with the results of the measured and finite element analysis that the fundamental frequency was about 2 Hz. The maximum amplitude of the pier top met the requirement that the lateral displacement shall not exceed 15 mm as specified in the reference [39]. Figure 8: Field test. Figure 9: Lateral amplitude. Compared with the fundamental vertical frequency, the fundamental lateral frequency was smaller and closer to the human gait frequency, which more easily produces lateral vibration. The fundamental vertical frequency met the comfort requirements specified in the Chinese C_J_[_69_-95_]_ code [33], so this paper only studied the lateral response of human-induced oscillation. There are two methods to evaluate the comfort of human-induced vibration, avoiding the sensitive frequency method and limiting the dynamic response value method. Avoiding the sensitive frequency method requires that the natural vibration frequency of the structure deviates from the step frequency range to prevent man-bridge resonance. The limited dynamic response method requires that the maximum vibration acceleration of the system meet the comfort limit requirements [40; 41; 42]. The existing pedestrian bridge specifications at home and abroad have different provisions for human-induced vibration (Table 3). Among them, the Chinese specifications do not specify the lateral comfort standard. The German code considers the influence of the deviation between the structural frequency and the pedestrian step frequency on the structure and believes that the system will have a severe vibration response only when the fundamental structural frequency is close to the pedestrian step frequency [43; 44]. We combined the resonance characteristics of modern steel structure bridges and the actual pedestrian crossing experience. This paper used the method of pedestrian acceleration limit specified in the design guide EN03 (2007) to evaluate comfort. The comfort distribution of human-induced vibration is shown in Figure 10.