The seismic damage to ancillary facilities on high-speed railway(HSR)bridges can affect the normal movement of trains.To propose the bridge deck acceleration response spectra of the typical HSR simply-supported girder...The seismic damage to ancillary facilities on high-speed railway(HSR)bridges can affect the normal movement of trains.To propose the bridge deck acceleration response spectra of the typical HSR simply-supported girder bridge for simplifying the seismic responses analysis of the facilities on bridges,the finite element models of the HSR multi-span simply-supported girder bridges with CRTSII track were established,and the numerical model was validated by tests.Besides,the effects of the span number,peak ground acceleration(PGA),pier height on the seismic acceleration and response spectra of the bridge deck were investigated.Afterward,the bridge acceleration amplification factor curves and bridge deck response spectra with different PGAs and pier heights were obtained.The formula for bridge deck acceleration amplification factor,with a 95%guarantee rate,was fitted.Moreover,the finite element models of the overhead contact lines(OCL)mounted on rigid base and bridges were established to validate the fitted formula.The results indicated that the maximum seismic acceleration response is in the midspan of the beam.The proposed formula for the bridge deck acceleration response spectra can be used to analyze the earthquake response of the OCL and other ancillary facilities on HSR simply-supported girder bridges.The bridge deck acceleration response spectra are conservative in terms of structural safety and can significantly improving the analysis efficiency.展开更多
The present study numerically explored the aerodynamic performance of a novel railway tunnel with a partially reduced cross-section.The impact of the reduction rate of the tunnel cross-section on wave transmissions wa...The present study numerically explored the aerodynamic performance of a novel railway tunnel with a partially reduced cross-section.The impact of the reduction rate of the tunnel cross-section on wave transmissions was analyzed based on the three-dimensional,unsteady,compressible,and RNG k-εturbulence model.The results highlight that the reduction rate(S)most affects pressure configurations at the middle tunnel segment,followed by the enlarged segments near access,and finally the exit.The strength of the newly generated compression wave at the tunnel junction where the cross-section abruptly changes increases exponentially with the decrease of the cross-sectional area.The maximum peak-to-peak pressureΔP on the tunnel and train surface for non-uniform tunnels is reduced by 10.7%and 13.8%,respectively,compared with those of equivalent uniform tunnels.Overall,the economic analysis suggests that the aerodynamic performance of the developed tunnel prototype surpasses those conventional tunnels based on the same excavated volume.展开更多
Road horizontal alignment contains three elements: straight line,circular arc,and clothoid.In AutoCAD,clothoid can only be fitted by polyline or spline,and the graphics which are separated from the road data are indep...Road horizontal alignment contains three elements: straight line,circular arc,and clothoid.In AutoCAD,clothoid can only be fitted by polyline or spline,and the graphics which are separated from the road data are independent of each other.Therefore,it is necessary to develop a new curve for road horizontal alignment.Firstly,the differential approximation and series integration methods for clothoid were discussed.Secondly,the geometric formulae for road line which contain the three elements were derived as a whole.Then,the advantages and feasibility of customizing a road line class,which was derived from the curve base class,were analyzed based on ObjectARX(AutoCAD Runtime eXtension) techniques.Finally,the data structure and operations for the road line class were stressed.The experimental results show that the road line can integrate the road elements,graphics and data to implement the graphics-oriented design,which can be widely used in road alignment design.展开更多
基金Project(HNTY2022K03)supported by the Hunan Tieyuan Civil Engineering Testing Co.,Ltd.,ChinaProject(52478573)supported by the National Natural Science Foundation of China。
文摘The seismic damage to ancillary facilities on high-speed railway(HSR)bridges can affect the normal movement of trains.To propose the bridge deck acceleration response spectra of the typical HSR simply-supported girder bridge for simplifying the seismic responses analysis of the facilities on bridges,the finite element models of the HSR multi-span simply-supported girder bridges with CRTSII track were established,and the numerical model was validated by tests.Besides,the effects of the span number,peak ground acceleration(PGA),pier height on the seismic acceleration and response spectra of the bridge deck were investigated.Afterward,the bridge acceleration amplification factor curves and bridge deck response spectra with different PGAs and pier heights were obtained.The formula for bridge deck acceleration amplification factor,with a 95%guarantee rate,was fitted.Moreover,the finite element models of the overhead contact lines(OCL)mounted on rigid base and bridges were established to validate the fitted formula.The results indicated that the maximum seismic acceleration response is in the midspan of the beam.The proposed formula for the bridge deck acceleration response spectra can be used to analyze the earthquake response of the OCL and other ancillary facilities on HSR simply-supported girder bridges.The bridge deck acceleration response spectra are conservative in terms of structural safety and can significantly improving the analysis efficiency.
基金Project(51975591)supported by the National Natural Science Foundation of China。
文摘The present study numerically explored the aerodynamic performance of a novel railway tunnel with a partially reduced cross-section.The impact of the reduction rate of the tunnel cross-section on wave transmissions was analyzed based on the three-dimensional,unsteady,compressible,and RNG k-εturbulence model.The results highlight that the reduction rate(S)most affects pressure configurations at the middle tunnel segment,followed by the enlarged segments near access,and finally the exit.The strength of the newly generated compression wave at the tunnel junction where the cross-section abruptly changes increases exponentially with the decrease of the cross-sectional area.The maximum peak-to-peak pressureΔP on the tunnel and train surface for non-uniform tunnels is reduced by 10.7%and 13.8%,respectively,compared with those of equivalent uniform tunnels.Overall,the economic analysis suggests that the aerodynamic performance of the developed tunnel prototype surpasses those conventional tunnels based on the same excavated volume.
基金Project(51108049)supported by the National Natural Science Foundation of ChinaProject(kfj090207)supported by Open Fund of Key Laboratory of Road Structure and Material of Ministry of Transport(Changsha University of Science and Technology),China
文摘Road horizontal alignment contains three elements: straight line,circular arc,and clothoid.In AutoCAD,clothoid can only be fitted by polyline or spline,and the graphics which are separated from the road data are independent of each other.Therefore,it is necessary to develop a new curve for road horizontal alignment.Firstly,the differential approximation and series integration methods for clothoid were discussed.Secondly,the geometric formulae for road line which contain the three elements were derived as a whole.Then,the advantages and feasibility of customizing a road line class,which was derived from the curve base class,were analyzed based on ObjectARX(AutoCAD Runtime eXtension) techniques.Finally,the data structure and operations for the road line class were stressed.The experimental results show that the road line can integrate the road elements,graphics and data to implement the graphics-oriented design,which can be widely used in road alignment design.
