In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditio...In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditional FEM of slab non-ballast track structures was improved.The multiscale FEM of CRTSII type slab nonballast track structures was established based on the general finite element program ABAQUs.Then the comparative calculation was made between various FEMs,showing that the high solution precision,fast modelling speed and high solution efficiency could be obtained.Therefore,the multiscale FEM was suitable for the parametric study on mechanical behaviour of CRTSII type slab non-ballast track structures,and then the key influence factor and constructions could be optimized.展开更多
CRTS-II slab ballastless track on bridge is a unique system in China high speed railway.The application of longitudinal continuous track system has obviously changed dynamic characteristics of bridge structure.The bri...CRTS-II slab ballastless track on bridge is a unique system in China high speed railway.The application of longitudinal continuous track system has obviously changed dynamic characteristics of bridge structure.The bridge system and CRTS-II track system form a complex nonlinear system.To investigate the seismic response of high speed railway(HSR)simply supported bridge-track system,nonlinear models of three-span simply supported bridge with piers of different height and CRTS-II slab ballastless track system are established.By seismic analysis,it is found that shear alveolar in CRTS-II track system is more prone to be damaged than bridge components,such as piers,girders and bearings.The result shows that the inconsistent displacement of bridge girders is the main cause of the CRTS-II track system’s damage.Then the rotational friction damper(RFD)is adopted,which utilizes the device’s rotation and friction to dissipate seismic energy.The hysteretic behavior of RFD is studied by numerical and experimental methods.Results prove that RFD can provide good hysteretic energy dissipation ability with stable performance.Furthermore,the analysis of RFD’s influence on seismic response of HSR bridge-track system shows that RFD with larger sliding force is more effective in controlling excessive inconsistent displacement where RFD is installed,though response of other bridge spans could slightly deteriorated.展开更多
Repeated train passages bring detrimental effects on train operations,especially at high speeds.In this study,a computational model consisting of moving train vehicles,track structure,and track foundation is used to i...Repeated train passages bring detrimental effects on train operations,especially at high speeds.In this study,a computational model consisting of moving train vehicles,track structure,and track foundation is used to investigate the stress distribution in the track substructure and underlying soil,particularly when the train speed approaches the critical speed via 2.5D finite element method.The numerical model has been validated by in-situ test results from a ballasted high-speed railway.The computational results reveal that the substructure is shown to be effective in reducing the stresses transmitted to the ground;however,a simple Boussinesq approximation is proved to be inaccurate because it cannot properly take account of the effect of multi-layered substructures and train speeds.It is acceptable to assume a simplified smooth track in the analysis model for determining the maximum stresses and displacements for a low-speed railway(≤100 km/h)but,for a high-speed one,the dynamic amplification effect of track irregularities must also be considered in subgrade design.Analysis of the stress paths revealed that the load speed and track irregularity increase the likelihood of failure for the subgrade;track irregularity can induce many times of principal stress rotations even under a simple single moving load.展开更多
基金supported by“111”Project(B18062)Fundamental Research Funds for the Central Universities(2019CDQYTM028).
文摘In order to make further study on the mechanical property of CRTSIII type slab non-ballast track structures,which was self-designed in China,based on the method of the multiscale finite element model(FEM),the traditional FEM of slab non-ballast track structures was improved.The multiscale FEM of CRTSII type slab nonballast track structures was established based on the general finite element program ABAQUs.Then the comparative calculation was made between various FEMs,showing that the high solution precision,fast modelling speed and high solution efficiency could be obtained.Therefore,the multiscale FEM was suitable for the parametric study on mechanical behaviour of CRTSII type slab non-ballast track structures,and then the key influence factor and constructions could be optimized.
基金The authors are grateful for the financial support from the Fundamental Research Funds for the Central Universities of Central South University(Project No.502221804)the National Natural Science Foundation of China(Project Nos.51878674,51878563)+1 种基金the Foundation for Key Youth Scholars in Hunan Province(Project No.150220077)the Project of Yuying Plan in Central South University(Project No.502034002).Any opinions,findings,and conclusions or recommendations expressed in this paper are those of the authors.
文摘CRTS-II slab ballastless track on bridge is a unique system in China high speed railway.The application of longitudinal continuous track system has obviously changed dynamic characteristics of bridge structure.The bridge system and CRTS-II track system form a complex nonlinear system.To investigate the seismic response of high speed railway(HSR)simply supported bridge-track system,nonlinear models of three-span simply supported bridge with piers of different height and CRTS-II slab ballastless track system are established.By seismic analysis,it is found that shear alveolar in CRTS-II track system is more prone to be damaged than bridge components,such as piers,girders and bearings.The result shows that the inconsistent displacement of bridge girders is the main cause of the CRTS-II track system’s damage.Then the rotational friction damper(RFD)is adopted,which utilizes the device’s rotation and friction to dissipate seismic energy.The hysteretic behavior of RFD is studied by numerical and experimental methods.Results prove that RFD can provide good hysteretic energy dissipation ability with stable performance.Furthermore,the analysis of RFD’s influence on seismic response of HSR bridge-track system shows that RFD with larger sliding force is more effective in controlling excessive inconsistent displacement where RFD is installed,though response of other bridge spans could slightly deteriorated.
基金the National Natural Science Foundation of China(No.52108308)the Start-up Fund of Fuzhou University(No.0050-510086 GXRC-20024)+1 种基金the Young Scientist Program of Fujian Provincial Natural Science Foundation of China(No.2020J05107)the Foundation of MOE Key Laboratory of Soft Soils and Geoenviromental Engineering,Zhejiang University,China(No.2020P05)。
文摘Repeated train passages bring detrimental effects on train operations,especially at high speeds.In this study,a computational model consisting of moving train vehicles,track structure,and track foundation is used to investigate the stress distribution in the track substructure and underlying soil,particularly when the train speed approaches the critical speed via 2.5D finite element method.The numerical model has been validated by in-situ test results from a ballasted high-speed railway.The computational results reveal that the substructure is shown to be effective in reducing the stresses transmitted to the ground;however,a simple Boussinesq approximation is proved to be inaccurate because it cannot properly take account of the effect of multi-layered substructures and train speeds.It is acceptable to assume a simplified smooth track in the analysis model for determining the maximum stresses and displacements for a low-speed railway(≤100 km/h)but,for a high-speed one,the dynamic amplification effect of track irregularities must also be considered in subgrade design.Analysis of the stress paths revealed that the load speed and track irregularity increase the likelihood of failure for the subgrade;track irregularity can induce many times of principal stress rotations even under a simple single moving load.
