Seismic Response Characteristics Of Overhead Contact System-Track-Bridge System

Due to the special geographical location,China’s seismic fault zones are very developed and seismicity is frequent.With the construction of high-speed railway network,it is inevitable to cross the seismic active areas.In China’s high-speed railway,a large number of bridges are used because of bridge instead of road.The bridge faces a severe test of seismic performance because of its high stiffness.At the same time,the high electrification rate of railway requires a large number of Overhead Contact System(OCS)and other ancillary facilities along the line.Based on the numerical simulation technology,this thesis establishes a simulation model of multi-span simply supported beam system considering track structure and OCS.And this thesis discussed the influence of ancillary facilities on the dynamic characteristics of the system and its seismic response characteristics.Based on IDA method,this thesis studies the seismic fragility of fasteners and OCS,and the influence of line longitudinal resistance on the seismic and fragility.The main contents include:(1)Taking the 7-32 m double-track simply supported beam bridge as the research object,the simulation model of OCS-track-bridge system considering the CRTS Ⅰ double-block ballastless track and catenary pillar(including cantilever)is established.(2)The dynamic characteristics of the system are studied by modal analysis.The results show that the track structure has a great influence on the dynamic characteristics of the system,which should be fully considered.and the influence of OCS has a small influence,which should be appropriately considered.(3)Taking the typical El-Centro wave and Taft wave as ground motion input,the seismic response characteristics of the system are discussed.The results show that the seismic response of the bridge and track structure is strong near the bridge abutments at both ends,and the seismic response of OCS is strong near the middle of the bridge.(4)The seismic fragility analysis of fasteners and OCS is carried out based on IDA method.The results show that the fasteners near the bridge abutment are damaged first,and side span end away from the bridge abutment is followed,and then the side span middle.The probability of damage in the middle span is very small,and the damage state is successively achieved in the order of the fixed end,the sliding end and the middle of span.OCS is damaged first from the middle of bridge span.And OCS is more sensitive to the earthquake than the fasteners.(5)Taking the ballasted track,ballastless track and small resistance fastener track as the research object,the influence of line longitudinal resistance on the seismic response and fragility of the structure is discussed.The results show that the line longitudinal resistance has little influence on bridge structure,and has a great influence on track structure.The fragility of fasteners varies according their different positions.The line longitudinal resistance has little influence on OCS and the influence is greatly affected by seismic wave characteristics.