Dynamic interaction analysis of bridges induced by a low-to-medium–speed maglev train

2020 ◽  
Vol 26 (21-22) ◽  
pp. 2013-2025 ◽  
Author(s):  
Dangxiong Wang ◽  
Xiaozhen Li ◽  
Lin Liang ◽  
Xiaowei Qiu
Keyword(s):  
Levitation Force ◽  
Interaction Analysis ◽  
Interaction Model ◽  
Field Tests ◽  
Electromagnetic Levitation ◽  
Dynamic Interaction ◽  
Superposition Method ◽  
Loading Frequency ◽  
Maglev Train ◽  
Medium Speed

The structure of low-to-medium–speed maglev trains significantly differs from that of traditional wheel/rail trains, leading to significant differences between the coupling vibration mechanism of the train and bridge systems. To determine the vertical dynamic interaction of the low-to-medium–speed maglev train–bridge system, a dynamic interaction model was established and studied, based on a proportional–integral–derivative active suspension control system and modal superposition method. The simulation model was validated through bridge dynamic field tests on the Changsha low-to-medium–speed maglev commercial line. The vertical dynamic characteristics of the system were analyzed for bridges with different girder heights. Subsequently, the mechanism of the vertical resonance of the bridge induced by the maglev train was analyzed carefully. The results show that reducing the bridge rigidity increases the electromagnetic levitation force, thereby increasing the dynamic response. The low-speed resonance in the bridge is caused by the circulation loading frequency of the adjacent electromagnetic force, whereas the normal-speed resonance is induced by the self-frequency of the electromagnetic levitation force.

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

2020 ◽  
Vol 23 (11) ◽  
pp. 2399-2413 ◽  
Author(s):  
Dangxiong Wang ◽  
Xiaozhen Li ◽  
Yuwen Wang ◽  
Qikai Hu
Keyword(s):  
Interaction Model ◽  
Field Tests ◽  
Dynamic Interaction ◽  
Dynamic Responses ◽  
Vertical Deflection ◽  
Maglev Train ◽  
Simply Supported ◽  
Medium Speed ◽  
The Stability ◽  
Important Design

The deflection ratio of the bridge is an important design parameter influencing the stability of the low-to-medium speed maglev train by affecting the levitation gap. This study focuses on the dynamic interaction of the low-to-medium speed maglev train and bridges with different vertical deflection ratios and investigates the required bridge vertical deflection ratio for the stability of the maglev train. The experimental investigation is carried out first. Then, a numerical dynamic interaction model is established and verified based on the field tests. And then, the influence of the vertical deflection ratio of a 25 m simply supported girder on the dynamic responses is discussed, as well as the bridges with the same deflection ratio but different span lengths. Finally, the maximum deflection ratios for the bridges with different span lengths are proposed and also compared with that of the existing maglev lines around the world. The study shows that when the deflection ratio reaches a certain level, the dynamic responses increase dramatically. The proposed allowable deflection ratios of bridges with different span lengths can not only ensure the smooth running of the train but also reduce the costs.

Dynamic Performance of the LMS Maglev Train–Track–Bridge System Under Uneven Settlement for Two Typical Bridges

2020 ◽  
pp. 2150006
Author(s):  
Dangxiong Wang ◽  
Xiaozhen Li ◽  
Ziyan Wu
Keyword(s):  
Numerical Model ◽  
Dynamic Performance ◽  
Interaction Model ◽  
Dynamic Interaction ◽  
Dynamic Responses ◽  
Train Track ◽  
Maglev Train ◽  
Medium Speed ◽  
Track Bridge ◽  
Bridge System

To investigate the dynamic performance of the low-to-medium-speed (LMS) maglev train and bridge system under uneven ground settlement, a refined vertical dynamic interaction model of the LMS maglev train–track–bridge system with uneven settlement is proposed. Firstly, the numerical model is verified based on the field test. Secondly, the dynamic performances of the system induced by uneven settlements are numerically analyzed. Furthermore, numerical studies are carried out to investigate the effect of various uneven settlement types, to compare the performances of the two typical bridges, and to assess the contribution of the F-rail in the presence of uneven settlement. The results show that uneven settlement has a significant enlargement effect on the dynamic responses of the car body and levitation module, but a very weak influence on the bridge. Both the patterns of uneven settlement and bridge types significantly affect the dynamic response of the maglev train to various levels. The numerical model excluding the track structure will overestimate the dynamic responses of the levitation module. It is suggested that the dynamic interaction model for the maglev train–track–bridge system be selected to simulate the influence of uneven settlement for better accuracy.

Dynamic Interaction Analysis of Maglev-Guideway System Based on a 3D Full Vehicle Model

2017 ◽  
Vol 17 (01) ◽  
pp. 1750006 ◽  
Author(s):  
Dong-Ju Min ◽  
Myung-Rag Jung ◽  
Moon-Young Kim ◽  
Jong-Won Kwark
Keyword(s):  
Dynamic Equilibrium ◽  
Interaction Analysis ◽  
Equations Of Motion ◽  
Dynamic Interaction ◽  
Surface Irregularity ◽  
Superposition Method ◽  
Vehicle Model ◽  
Equilibrium Equations ◽  
Coupled Equations ◽  
Maglev Vehicle

The purpose of this paper is to develop a detailed 3D maglev vehicle and guideway model and investigate the dynamic response characteristics of the coupled system. For this, the maglev vehicle is modeled as one cabin and four bogies having eight electromagnetics, four sensors, and four secondary suspensions based on the Urban Transit Maglev (UTM) system in Korea. The 3D dynamic equilibrium equations of the cabin and bogies are derived by considering the actively controlled electromagnetic forces. Also, the equations of motion for the guideway are derived using the modal superposition method for vertical, lateral, and torsional modes. The resulting coupled equations of motion are then solved using a predictor–corrector iterative algorithm. Finally, through the numerical simulation of the developed system, the responses using the 3D maglev vehicle model are compared with those obtained by the corresponding 2D model. The effects of surface irregularity on the dynamic interaction behaviors are then evaluated for increasing vehicle speeds. Particularly, the 3D resonance conditions of the guideway girder and the maglev vehicle are presented considering the resonance conditions due to equidistant moving loads. In addition, some resonance phenomena are rigorously explored, including the lateral resonance by a series of vehicles running on a girder.

Influence of the track structure on the vertical dynamic interaction analysis of the low-to-medium-speed maglev train-bridge system

2019 ◽  
Vol 22 (14) ◽  
pp. 2937-2950 ◽  
Author(s):  
Dangxiong Wang ◽  
Xiaozhen Li ◽  
Lin Liang ◽  
Xiaowei Qiu
Keyword(s):  
High Frequency ◽  
Local Deformation ◽  
Dynamic Interaction ◽  
Track Structure ◽  
Train Track ◽  
Maglev Train ◽  
Influence Mechanism ◽  
Medium Speed ◽  
Track Bridge ◽  
Bridge System

The low-to-medium-speed maglev train is stably suspended near the rated suspension gap. The suspension force acts directly on the track and is transmitted to the bridge. The maglev track structure is novel, and the influence mechanism of the track structure on the coupled vibration of the maglev train-bridge system is unknown. Therefore, in this study, we propose vertical dynamic interaction models of the low-to-medium-speed maglev train-bridge system and the low-to-medium-speed maglev train-track-bridge system to analyse the influence mechanism of the maglev track structure on the vertical dynamic interaction of the low-to-medium-speed maglev train-bridge system. The vibration characteristics of the F-rail and the influence mechanism of the track structure on the dynamic responses of the bridge are discussed in detail. The study verifies that the local deformation of the F-rail is self-evident and cannot be ignored. In addition, the influence of the F-rail on the dynamic interaction of the maglev train-bridge system is mainly reflected in two aspects: first, the vibration of the bridge in the high-frequency band increases due to the high frequency and intensive local vibration of the F-rail itself. Second, the vibrations of the bridge and the F-rail in the low-frequency band increase due to the periodic irregularities caused by the local deformation of the F-rail. In this study, we consider the vertical dynamic interaction model of the low-to-medium-speed maglev train-track-bridge system.

scholarly journals Higher-order clinical risk factor interaction analysis for overall mortality in maintenance hemodialysis patients

2020 ◽  
Vol 11 ◽  
pp. 204062232094906
Author(s):  
Cheng-Hong Yang ◽  
Sin-Hua Moi ◽  
Li-Yeh Chuang ◽  
Jin-Bor Chen
Keyword(s):  
Interaction Analysis ◽  
Interaction Model ◽  
Higher Order ◽  
Survival Outcome ◽  
Maintenance Hemodialysis ◽  
Order Interaction ◽  
Statistical Approaches ◽  
The Impact ◽  
Factor Interaction ◽  
Overall Mortality

Background and Aims: In Taiwan, approximately 90% of patients with end-stage renal disease receive maintenance hemodialysis. Although studies have reported the survival predictability of multiclinical factors, the higher-order interactions among these factors have rarely been discussed. Conventional statistical approaches such as regression analysis are inadequate for detecting higher-order interactions. Therefore, this study integrated receiver operating characteristic, logistic regression, and balancing functions for adjusting the ratio in risk classes and classification errors for imbalanced cases and controls using multifactor-dimensionality reduction (MDR-ER) analyses to examine the impact of interaction effects between multiclinical factors on overall mortality in patients on maintenance hemodialysis. Meterials and Methods: In total, 781 patients who received outpatient hemodialysis dialysis three times per week before 1 January 2009 were included; their baseline clinical factor and mortality outcome data were retrospectively collected using an approved data protocol (201800595B0). Results: Consistent with conventional statistical approaches, the higher-order interaction model could indicate the impact of potential risk combination unique to patients on maintenance hemodialysis on the survival outcome, as described previously. Moreover, the MDR-based higher-order interaction model facilitated higher-order interaction effect detection among multiclinical factors and could determine more detailed mortality risk characteristics combinations. Conclusion: Therefore, higher-order clinical risk interaction analysis is a reasonable strategy for detecting non-traditional risk factor interaction effects on survival outcome unique to patients on maintenance hemodialysis and thus clinically achieving whole-scale patient care.

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