Analysis Of The Adaptability Of Existing Railway Bridges Under The Condition Of Transportation Expansion

With the continuous development of the national economic,there is a pressing need for the increasing capacity of railway transportation,and Heavy haul transportation is one of the main means to enhance the efficiency of railway transportation,at the same time,the axle load of freight cars is an important criterion for heavy haul transportation.In order to clarify whether the existing railway bridges designed according to the CR live loading can meet the requirements of heavy haul transportation,this paper focuses on the adaptability of some existing railway bridges in the range of spans from 6 m to 32 m when the axle weight of the freight car rises,and the results are as follows:(1)Based on the bending moment effect of mid span and beam end shear effect under the effect of CR live loading,the paper analyzed the live load reserves of the 6~32 m bridges under the kinds of heavy-haul freight cars.(2)Under the condition of without considering the structure degradation,the paper analyzed the adaptability of intensity,stiffness and crack resistance of 8m,12 m average height and low height concrete beams and 24 m,32 m normal height and super low height prestressed beams.Under the 27 t and 30 t axle load,the stress of the outer layer rebar of the beam is more than the allowable value.(3)In this paper,the finite element software MIDAS/Civil is used to establish the bridge model.Combined with the actual working conditions,the random function of lateral rocking force of the train was worked out to research the dynamic response law of 12 m normal height simply supported beam and 12 m low height simply supported beam under different working conditions.The analysis shows that the structural dynamic response increases as the speed increases within a certain speed range,in another certain speed range dynamic response decreases as the speed increase,the dynamic response of the structure increases when axle load increases,but it is not obvious in some speed conditions.(4)We take the operational performance tests on 263 # and 269 # bridges of ShuoHuang Railway to get the measured data of the dynamic response of the bridge,and also provide the measured data for the research.