Effect Of Floating Slab Track On Vibration Absorption Performance Of High Speed Railway Steel Truss Bridge

With the rapid development of railway transportation in China,railway traffic volume,vehicle weight and vehicle speed have been greatly improved,violent vibration of steel truss bridges makes steel plate corrosion,fatigue cracks,bolt loosening or fracture,rod deformation and other diseases,which seriously affects the normal use of existing railway bridges.Steel spring floating slab system is a kind of track structure for vibration reduction.At present,it is mainly used in subway and elevated lines in urban.Noise reduction effect of steel spring floating slab system is mostly analyzed,but the effect of vibration reduction on bridge structure damage was little-studied studied.In this paper,based on the research background of a 128-meter span steel truss bridge,a complete finite element analysis model of high-speed train-floating slab track-steel truss bridge coupling system is established by ABAQUS software.The effects of floating slab track structure and slab track structure on vibration reduction of bridges are compared.The influence of structural parameters of floating slab track on its vibration reduction effect is studied.The effect of floating slab track vibration reduction effect on the life of steel bridges is analyzed.The details are as follows:(1)Referring to the theory of vehicle-rail-bridge coupling dynamics,a three-dimensional coupled dynamic finite element model of steel spring floating slab track and common slab track is established.The real train loads are applied to the two kinds of track structures respectively.The numerical simulation results of vibration response of slab track system in time domain and frequency domain are compared with the measured data,and the correctness of wheel-rail contact model is verified.Comparing the vibration response of bridge in mid-span between floating slab track system and slab track system on bridge,the analysis shows that the application of steel spring floating slab track structure can effectively reduce the mid-high frequency vibration of bridge span,but it will increase the acceleration amplitude of structure above the track slab and the acceleration of car body within the safe range,which will not affect the safety of driving.(2)Transient dynamic analysis of high speed train-floating slab track-steel truss bridge coupling system finite element model is carried out.The effects of steel spring stiffness,steel spring damping,floating slab density and stiffness of Under-Rail fasteners on the vibration characteristics of track system and vehicle are studied.The study shows that the vibration response of bridge structure increases with the decrease of stiffness of steel spring,the increase of damping of steel spring,the increase of density of floating plate and the decrease of stiffness of fasteners.(3)Referring to the design drawings of steel bridges,the detail model of integral joints in the bridge span is established,the static analysis of the detail model is carried out,and the stress concentration area is obtained.The stress time history curve of integral joints in the stress concentration area is obtained by combining the analysis of the coupled model of train-rail-bridge.The fatigue characteristics of welds in the stress concentration area are analyzed,and the service life of two types of track bridges,slab track and floating slab track,is estimated.It is found that the application of floating slab track structure on the bridge can effectively reduce the fatigue damage of the whole bridge joint structure and prolong the service life of the bridge.In this paper,the transient dynamic analysis of the coupling system of high-speed train steel spring floating slab track-steel truss bridge is carried out,and the vibration laws of the system is determined.Through the analysis of fatigue performance of integral joints in mid span,it is determined that the steel spring floating slab track structure can improve the fatigue performance of steel bridge which provides a new idea for the service life extension of existing railway bridges on high-speed railway.