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

The development of heavy haul transportation,puts forward higher requirements for the mechanical performance of heavy haul railway bridge in service,Steel truss girder bridge as a key structural bridge on heavy-haul transportation line,the increase of train axle load and traffic volume inevitably lead to the increase of fatigue stress amplitude and the number of fatigue actions of steel truss bridges,which leads to the structural diseases of bridges.Once the diseases occur,the structural stress will be adversely affected.In this paper,the 64 m single-track steel truss girder bridge of Shuohuang Railway was taken as the research object.By means of finite element analysis,field measurement and operation performance test,the mechanical properties of bridge structures,the causes of diseases and the effects of diseases on bridge structures under heavy-haul transportation were studied.The main research contents were as follows:(1)The stress of each member state of heavy haul train load 64 m single Steel truss girder bridge was analyzed and calculated,researched the heavy haul transportation to the structure stress influence,and in accordance with the existing norms for the force calculation of bridge structure.(2)By using the method of field measurement,to determine the 64 m single steel truss girder bearing connection angle cracks mainly due to bearing height existence leads to structural member forces too large.(3)The calculation model of 64 m steel truss bridge was established by using the finite element software Midas Civil.The bearing height difference was simulated by forced node displacement.The influence of bearing height difference on the internal force of bridge members and the vibration characteristics of bridge structure was analyzed.The results show that the internal force of some members of the bridge structure increases obviously due to the difference of bearing height,and the lateral amplitude and acceleration of the bridge structure increase obviously,which affects the driving safety.(4)Through the operation performance test of the bridge structure before and after the disease treatment,the influence of the disease on the stress of the bridge structure was studied and compared the test data,it is found that the bearing height difference leads to the uneven stress of the bridge structural members,the increase of internal forces of some members,and the uneven distribution of internal forces of the members.In addition,the bearing height difference also causes the transverse amplitude and acceleration of the bridge structure to exceed the norm limit when the train passed through.After disease treatment,the internal force of the members was reduced,the force was uniform,the transverse amplitude and acceleration of the bridge span were obviously reduced,and the effect of disease treatment was obvious.