The Limit of the Lateral Fundamental Frequency and Comfort Analysis of a Straddle-Type Monorail Tour Transit System

Abstract

The straddle-type monorail tour transit system is a light overhead steel structure, and the lateral stiffness is generally low. However, the limit of the lateral natural vibration frequency is not clear in the current codes of China, and designers may ignore it. Weak lateral stiffness will lead to a violent vibration during vehicle operation and crowds walking, affecting human comfort and structural safety. Based on a practical project, we tested the acceleration of a monorail vehicle under full load conditions, and its running stability and ride comfort were assessed. Then, the impact of pedestrians on lateral vibration under some working conditions was measured and analyzed. Furthermore, the influence of different structural parameters on the lateral fundamental frequency was investigated. The results showed the following: (i) The vehicle’s running stability and riding comfort was good. However, human comfort was poor due to the weak lateral stiffness of the structure, which was affected by human-induced vibration. (ii) The comprehensive response of the structure increased with the increase in walking frequency, increased with the increase in the number of people working or weight, and the growth speed slowed down. (iii) The structural stiffness was most sensitive to the change in steel column diameter. (iv) The recommended value of the lateral fundamental frequency limit for different spans of the straddle-type monorail tour transit system was put forward. The recommended lower limit of fundamental frequency for a 15 m span is 5.0 Hz, for an 18 m span it is 3.5 Hz, and for a 25 m span it is 2.8 Hz.

Evaluation of the Dynamic Amplification Factors of a Monorail Tourism Transit System Based on Probability Statistics

“…Ji [15] conducted a large number of measurements on the track irregularity of travel transportation system, graded the irregularity spectrum, and established a grade evaluation system of the irregularity spectrum of the monorail top plate, as sh in Figure 3. In this paper, the research results are utilised in the analysis, and the irr…”

“…Ji [15] conducted a large number of measurements on the track irregularity of the travel transportation system, graded the irregularity spectrum, and established a five-grade evaluation system of the irregularity spectrum of the monorail top plate, as shown in Figure 3. In this paper, the research results are utilised in the analysis, and the irregularity spectrum of each classification (hereinafter referred to as Spectrum 1, Spectrum 2, Spectrum 3, Spectrum 4, and Spectrum 5) is imported into the SIMPACK for calculation, which is used as the external excitation of the vehicle-bridge coupling model.…”

“…The system adopts a steel structure, and the whole line is erected by bridges without the need to build a special construction right-ofway; it adopts a power supply with a rail, which can effectively reduce noise pollution [1,2]. The advantages of traditional cross-seat urban transportation systems are borrowed by the MTTS, but there are some differences in the axle loads, structural parameters, technical parameters, and structural linear design [3][4][5]. For example, the MTTS adopts a lightweight steel girder and steel column structure, while the traditional urban transportation system generally adopts a prestressed concrete structure; the travel system belongs to the category of amusement rides, and its speed is slower than that of the traditional transportation system, with a maximum speed of no more than 40 km/h.…”