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Dynamic analysis of coupled train - ladder track - elevated bridge system
He Xia,Yushu Deng,Chaoyi Xia,G. De Roeck,Lin Qi,Lu Sun 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.5
As a new type of vibration reduction, the ladder track system has been successfully used in engineering. In this paper, a numerical model of the train-track-viaduct system is established to study the dynamic responses of an elevated bridge with ladder track. The system is composed of a vehicle submodel, a track submodel and a bridge submodel, with the measured track irregularities as the system self-excitation. The whole time histories of a train running through an elevated bridge with 3×27m continuous PC box girders are simulated. The dynamic responses of the bridge such as deflections, lateral and vertical accelerations, and the vehicle responses such as derailment factors, offload factors and car-body accelerations are calculated. The calculated results are partly validated through the comparison with the experimental data. Compared to the common slab track, adapting the ladder sleeper can effectively reduce the accelerations of the bridge girder, and also reduce the car-body accelerations and offload factors of the train vehicle.
Dynamic analysis of coupled train - ladder track - elevated bridge system
Xia, He,Deng, Yushu,Xia, Chaoyi,De Roeck, G.,Qi, Lin,Sun, Lu Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.5
As a new type of vibration reduction, the ladder track system has been successfully used in engineering. In this paper, a numerical model of the train-track-viaduct system is established to study the dynamic responses of an elevated bridge with ladder track. The system is composed of a vehicle submodel, a track submodel and a bridge submodel, with the measured track irregularities as the system self-excitation. The whole time histories of a train running through an elevated bridge with $3{\times}27m$ continuous PC box girders are simulated. The dynamic responses of the bridge such as deflections, lateral and vertical accelerations, and the vehicle responses such as derailment factors, offload factors and car-body accelerations are calculated. The calculated results are partly validated through the comparison with the experimental data. Compared to the common slab track, adapting the ladder sleeper can effectively reduce the accelerations of the bridge girder, and also reduce the car-body accelerations and offload factors of the train vehicle.
He Xia,Chaoyi Xia,Nan Zhang,Qin Ma,Xuan Wu 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.59 No.4
Safety is the prime concern for a high-speed railway bridge, especially when it is subjected to a collision. In this paper, an analysis framework for the dynamic responses of train-bridge systems under collision load is established. A multi-body dynamics model is employed to represent the moving vehicle, the modal decomposition method is adopted to describe the bridge structure, and the time history of a collision load is used as the external load on the train-bridge system. A (180+216+180) m continuous steel trussedarch bridge is considered as an illustrative case study. With the vessel collision acting on the pier, the displacements and accelerations at the pier-top and the mid-span of the bridge are calculated when a CRH2 high-speed train running through the bridge, and the influence of bridge vibration on the running safety indices of the train, including derailment factors, offload factors and lateral wheel/rail forces, are analyzed. The results demonstrate that under the vessel collision load, the dynamic responses of the bridge are greatly enlarged, threatening the running safety of high-speed train on the bridge, which is affected by both the collision intensity and the train speed.
Dynamic analysis of high-speed railway train-bridge system after barge collision
Xia, Chaoyi,Ma, Qin,Song, Fudong,Wu, Xuan,Xia, He Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.1
In this paper, a framework is proposed for dynamic analysis of train-bridge systems with a damaged pier after barge collision. In simulating the barge-pier collision, the concrete pier is considered to be nonlinear-inelastic, and the barge-bow is modeled as elastic-plastic. The changes of dynamic properties and deformation of the damaged pier, and the additional unevenness of the track induced by the change of deck profile, are analyzed. The dynamic analysis model for train-bridge coupling system with a damaged pier is established. Based on the framework, an illustrative case study is carried out with a $5{\times}32m$ simply-supported PC box-girder bridge and the ICE3 high-speed train, to investigate the dynamic response of the bridge with a damaged pier after barge collision and its influence on the running safety of high-speed train. The results show that after collision by the barge, the vibration properties of the pier and the deck profile of bridge are changed, forming an additional unevenness of the track, by which the dynamic responses of the bridge and the car-body accelerations of the train are increased, and the running safety of high-speed train is affected.
He, Ying-Xia,Ye, Cheng-Lin,Zhang, Pei,Li, Qiao,Park, Chae Gyu,Yang, Kun,Jiang, Ling-Yu,Lv, Yin,Ying, Xiao-Ling,Ding, Hong-Hui,Huang, Hong-Ping,Mambwe Tembo, John,Li, An-Yi,Cheng, Bing,Zhang, Shu-Sheng American Society for Microbiology 2019 Infection and immunity Vol.87 No.1
<P><I>Yersinia pseudotuberculosis</I> is a Gram-negative enteropathogen and causes gastrointestinal infections. It disseminates from gut to mesenteric lymph nodes (MLNs), spleen, and liver of infected humans and animals.</P><P><I>Yersinia pseudotuberculosis</I> is a Gram-negative enteropathogen and causes gastrointestinal infections. It disseminates from gut to mesenteric lymph nodes (MLNs), spleen, and liver of infected humans and animals. Although the molecular mechanisms for dissemination and infection are unclear, many Gram-negative enteropathogens presumably invade the small intestine via Peyer’s patches to initiate dissemination. In this study, we demonstrate that <I>Y. pseudotuberculosis</I> utilizes its lipopolysaccharide (LPS) core to interact with CD209 receptors, leading to invasion of human dendritic cells (DCs) and murine macrophages. These <I>Y. pseudotuberculosis</I>-CD209 interactions result in bacterial dissemination to MLNs, spleens, and livers of both wild-type and Peyer’s patch-deficient mice. The blocking of the <I>Y. pseudotuberculosis</I>-CD209 interactions by expression of O-antigen and with oligosaccharides reduces infectivity. Based on the well-documented studies in which HIV-CD209 interaction leads to viral dissemination, we therefore propose an infection route for <I>Y. pseudotuberculosis</I> where this pathogen, after penetrating the intestinal mucosal membrane, hijacks the <I>Y. pseudotuberculosis</I>-CD209 interaction antigen-presenting cells to reach their target destinations, MLNs, spleens, and livers.</P>
Chaoyi Xia,Kunpeng Wang,Jiacheng Huang,He Xia,Lin Qi,Xuan Wu 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.81 No.1
The dynamic responses of a pier-pile-soil system subjected to a barge/flotilla collision are analyzed. A coupled highspeed train and bridge system with a damaged pier after barge/flotilla collision is established by taking the additional unevenness of the track induced by the damaged pier as the self-excitation of the system. The whole process of a CRH2 high-speed train running on the 6×32 m simply-supported PC (prestressed concrete) box-girder bridge with a damaged pier is simulated as a case study. The results show that the lateral displacements and accelerations of the bridge with a damaged pier are much greater than the ones before the collision. The running safety indices of the train increase with the train speed as well as with the number of barges in the flotilla. In flotilla collision, the lateral wheel/rail forces of the train exceed the allowable values at a certain speed, which influences the running safety of the trains.
Jiang-He Zhao,Wei-Dong Xie,Tong Shen,Xia Yang,Hong Zhao,Xia Li 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.7
A new eremophilane sesquiterpenoid, namely, 3β-angeloyloxy-6β,8β-dihydroxy-9β-senecioyloxyeremophil-7(11)-en-12,8α-lactone, along with eight known sesquiterpenoids, was isolated from the rhizome of Farfugium japonicum. The structures of all isolates were identified based on analyses of spectroscopic data (HRESIMS, IR, 1D, and 2D NMR) and comparison with literature data. The inhibitory effects of compounds 1-4 on nitric oxide production in lipopolysaccaride-activated mouse macrophages were also evaluated.
Dynamic analysis of high-speed railway train-bridge system after barge collision
Chaoyi Xia,Qin Ma,Fudong Song,Xuan Wu,He Xia 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.67 No.1
In this paper, a framework is proposed for dynamic analysis of train-bridge systems with a damaged pier after barge collision. In simulating the barge-pier collision, the concrete pier is considered to be nonlinear-inelastic, and the barge-bow is modeled as elastic-plastic. The changes of dynamic properties and deformation of the damaged pier, and the additional unevenness of the track induced by the change of deck profile, are analyzed. The dynamic analysis model for train-bridge coupling system with a damaged pier is established. Based on the framework, an illustrative case study is carried out with a 5×32 m simply-supported PC box-girder bridge and the ICE3 high-speed train, to investigate the dynamic response of the bridge with a damaged pier after barge collision and its influence on the running safety of high-speed train. The results show that after collision by the barge, the vibration properties of the pier and the deck profile of bridge are changed, forming an additional unevenness of the track, by which the dynamic responses of the bridge and the car-body accelerations of the train are increased, and the running safety of high-speed train is affected.