Dynamic analysis of the interactions between a low-to-medium-speed maglev train and a bridge: Field test results of two typical bridges

Abstract

The rated suspension gap of a low-to-medium-speed maglev train with electromagnetic suspension is normally 8-10 mm. However, while either passing over a bridge or being stationary on one, the maglev train deforms the bridge and therefore alters the suspension gap. Hence, a problem arises due to coupled vibrations between the maglev train and its supporting bridge. In the study reported here, field experiments were conducted on the Chinese Changsha maglev line, which was the first commercial low-to-medium-speed maglev line in China. The focus is on two types of prestressed double-track concrete bridges on the maglev line. One is a simply supported girder with a span of 25 m, while the other is a continuous girder designed as 25 þ 35 þ 25 m. The accelerations and vertical dynamic deflections of the two bridges at midspan were measured while a five-module low-to-medium-speed maglev train with electromagnetic suspension either passed over or was stationary on either bridge, as were the accelerations of the car body and the suspension frame. The basic dynamic characteristics of the two bridges are analysed and compared with those of bridges in various typical maglev lines. The vibration characteristics of the two bridges, the car body and the suspension frame are studied in the time and frequency domains for the maglev train running at normal speeds, low speeds and when stationary. The influences of the speed on the dynamic characteristics are discussed. Some comparisons with other studies are also carried out, including the effects of bridge parameters on the coupled vibrations and the running stability of a low-to-medium-speed maglev and a CRH2C wheel/rail train. Significant conclusions are drawn from the analysis: increasing the rigidity and mass of the bridge can significantly reduce its vibration; increasing the span and deflection of the bridge increases the vibrations of the car body and the suspension frame; the dynamics of the maglev vehicle and bridges are different when the maglev train runs at normal speeds (more than 30 km/h), low speeds (less than 30 km/h) and when being stationary. The running stability of a low-to-medium-speed maglev train is better than that of a CRH2C high-speed train. The present study provides a test basis for further research on the mechanisms for coupled vibrations of maglev train-bridge systems.

Review of annual progress of bridge engineering in 2019

“…For the coupling vibration, Zhang and Huang (2019) established a 10-degree-of-freedoms high-speed maglev train-bridge coupled vibration model using model modification methods and verified it based on the field tests. Based on the Changsha low-tomedium-speed (LMS) maglev commercial line, Li et al (2018b) compared the dynamic response characteristics of the system when LMS maglev trains run on the different bridges considering the track structure (shown in Fig. 22).…”

Dynamic interaction of the low-to-medium speed maglev train and bridges with different deflection ratios: Experimental and numerical analyses

“…This section discusses the effect on the deflection ratio limit of the bridge span length including 15, 20, 25, 30, 35 and 40 m, respectively. In order to clearly discuss only the influence mechanism of the vertical rigidity of the bridge on the acceleration induced by the maglev train, the mass per metre of the bridge needs to remain the same (Han et al, 2009; Li et al, 2018b). Hence, maintaining the cross-sectional shape of the bridge and the girder height (the mass per metre of the bridge remain the same) and adjusting the elastic modulus, the deflection ratios of the bridges are all L /3000.…”

Dynamic Responses of a Metro Train-Bridge System under Train-Braking: Field Measurements and Data Analysis

“…The FFT results of the side span's acceleration signal showed two frequency peaks (at about 1.95 Hz and 3.6 Hz) and four frequency peaks (at about 2.051, 4.053, 6.055, and 10.11 Hz) corresponding to the free and forced vibration parts, respectively, as shown in Figure 6d. The dominant frequency of the free vibration part is the natural frequency for bridges [24]. Therefore, the first and second fundamental vertical frequencies of the continuous, three-span, rigid-frame bridge corresponding to approximately 2 and 4 Hz, respectively, were obtained by performing spectrum analysis of the measured acceleration data.…”

“…6d. The dominant frequency of the free vibration part is the natural frequency for bridges [24]. Therefore, the first and second fundamental vertical frequencies of the continuous, three-span, rigid-frame bridge corresponding to approximately 2 and 4 Hz, respectively, were obtained by performing spectrum analysis of the measured acceleration data.…”