Experimental Study On Operational Performance Of 8m Steel-concrete Composite Beams In Service Under Heavy-haul Transportation Conditions

In order to adapt to the development of heavy haul transportation in China,the existing railways need to be extended.However,in the process of capacity expansion and transformation,due to the increase of axle-load and traffic volume of trains,the existing small and medium span concrete bridges have suffered serious diseases.In order to ensure the long term operation safety of the bridge under heavy haul transportation,the beam replacement method is adopted to strengthen the bridge.In order to test the rationality and effectiveness of the new beam,the new beam should be researched.In this paper,the 8m steel-concrete composite beam bridge in Baoheng road of Shuohuang railway is taken as the research object,and the mechanical and operational performance of 8m steel-concrete composite beam under the load of 21 t,23t,25 t and 30 t axle-load trains is analyzed by finite element simulation and field test.The main research contents are as follows:(1)The research status of heavy-haul railway is introduced,and the development status of steel-concrete composite beam meeting the requirements of heavy haul transportation is elaborated.(2)The mechanism,structure and dynamic characteristics of the steel plate beam bridge meeting the requirements of heavy haul transformation are described in detail.(3)The finite element calculation software Midas civil was used to establish the calculation model of 8m steel-concrete composite beam,and the deformation,principal stress and dynamic characteristics of the beam.21 t,23t,25 t and 30 t axle-load trains were obtained through calculation.The large stress amplitude was found as the fatigue detail,which was tested according to the code.The results show that the cross electric deflection,the normal stress of the upper flange,the normal stress of the lower flange,the normal stress of the concrete roof,the dynamic characteristics and the fatigue performance of the copper-concrete composite beam meet the requirements of the code.(4)By operating performance test,it can get a new change of steel-concrete composite beam structure under operating load across the horizontal amplitude,across different backbone to the amplitude,the dynamic deflection and dynamic strain and top bridge fill transverse agents operating performance indexes.Comparing with the value of a certain,analysis and evaluation in new steel-concrete composite beam according to the real working conditions of beam;Compared with the operational performance test data before beam replacement,the beam replacement effect should be texted.The test results show that the beam replacement is effective and the measured values after beam replacement meet the requirements of the code.