Analysis On Crack Resistance Of Simply Supported Girder Bridge Under The Condition Of Heavy-haul Transportation

With the increase of China's heavy haul train axle load and transport volume,there are some inclined cracks in the end of some prestressed concrete beam in the existing railway,which has a certain impact on the operation and safety of the bridge.Regard the 32 m prestressed concrete simply supported girder bridge of Shuo Huang heavy haul railway as the research object,use the method of combine finite element simulation with real-bridge experiment test to analyze the crack resistance of simply supported girder bridge under the condition of heavy-haul transportation.The main contents of the dissertation are as follows.(1)Using the finite element method to analyze the shear stress and principal stress under dead load and heavy haul train live load of 32 m average height prestressed concrete simply supported girder bridge,to find out the maximum position of shear stress in the end of beam,and to analyze the crack resistance of the bridge.The simulation results indicated that the maximum position of shear stress in the end of beam of 32 m average height bridge is in the cross-section within 1.60 m from the end of bear.The shear stress is the main factor to control the inclined cracks,the shear stress is larger than the allowable shear stress of concrete,meet the requirement of material in terms of specification,but reduce the safety stock of the bridge structure.(2)The static test is carried out on the intact beam and the beam with inclined crack.The influence of the inclined crack in the end of the beam on the mid-span deflection,the mid-span soleplate concrete stress,the shear stress and the principal stress of the beam have been studied.The simulation results indicated that the mid-span deflection increment,the mid-span soleplate concrete stress increment,the shear stress increment and the principal stress increment of the end beam of the cracked beam are better than the intact beam,the biggest discrepancy is 25.8%.This indicates that the inclined cracks can reduce the whole bearing capacity of the bridge structure.(3)The dynamic loading test is carried out on the intact beam and the beam with inclined crack.This paper has studied the influence of the inclined cracks on the vibration feature of the bridge,including the transverse amplitude,the transverse acceleration,the vertical amplitude and the vertical acceleration.The simulation results indicated that the transverse amplitude,the transverse acceleration,the vertical amplitude and the vertical acceleration are better than the intact beam,the biggest discrepancy is 26.8%.This indicated that the inclined cracks can weaken the transverse stiffness and vertical stiffness of the bridge structure in different degrees.(4)According to the crack of prestressed concrete simply supported girder bridge,using the method of grouting,pasting steel plate,external prestressing and pasting carbon fibre sheet to reinforce.