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
Significant diurnal temperature variations in mountainous rack railways cause stiffness mismatches between the rack structure and simply supported bridges,leading to critical failures like bolt loosening and rack frac...Significant diurnal temperature variations in mountainous rack railways cause stiffness mismatches between the rack structure and simply supported bridges,leading to critical failures like bolt loosening and rack fractures.This study develops a dynamic model of the vehicle-rack-bridge system based on train-track-bridge interaction theory,integrating gear-rack meshing and wheel-rail contact mechanisms.The model analyzes the dynamic response of bridges with varying spans under combined thermal and dynamic loading.Numerical simulations,conducted using finite element analysis,reveal peak vibration accelerations of 1.3 m/s^(2)for the rack,3.0 m/s^(2)for the rail,1.2 m/s^(2)for the sleeper,and 0.1 m/s^(2)for the bridge,with maximum stresses of 3 MPa in the rack,8 MPa in the rail,and 25 MPa in connecting bolts.The results show significant span-dependent amplification of stress and strain in the rack system under thermo-mechanical loading,exceeding material strength limits at 60-meter spans.An innovative elastic connection method is proposed to mitigate stress concentrations effectively,en-hancing system durability.This study introduces a novel approach to modeling complex thermo-mechanical interactions in rack railway systems,validated through extensive simulations,and provides a practical solution for improving structural resilience,offering theoretical guidance for optimizing rack-bridge system design to ensure operational safety in extreme environmental conditions.展开更多
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Supported by the Sichuan Science and Technology Program(Grant Nos.2021YFD0211,2023ZDZX0011).
文摘Significant diurnal temperature variations in mountainous rack railways cause stiffness mismatches between the rack structure and simply supported bridges,leading to critical failures like bolt loosening and rack fractures.This study develops a dynamic model of the vehicle-rack-bridge system based on train-track-bridge interaction theory,integrating gear-rack meshing and wheel-rail contact mechanisms.The model analyzes the dynamic response of bridges with varying spans under combined thermal and dynamic loading.Numerical simulations,conducted using finite element analysis,reveal peak vibration accelerations of 1.3 m/s^(2)for the rack,3.0 m/s^(2)for the rail,1.2 m/s^(2)for the sleeper,and 0.1 m/s^(2)for the bridge,with maximum stresses of 3 MPa in the rack,8 MPa in the rail,and 25 MPa in connecting bolts.The results show significant span-dependent amplification of stress and strain in the rack system under thermo-mechanical loading,exceeding material strength limits at 60-meter spans.An innovative elastic connection method is proposed to mitigate stress concentrations effectively,en-hancing system durability.This study introduces a novel approach to modeling complex thermo-mechanical interactions in rack railway systems,validated through extensive simulations,and provides a practical solution for improving structural resilience,offering theoretical guidance for optimizing rack-bridge system design to ensure operational safety in extreme environmental conditions.
