| Steel-concrete composite structure bridge has excellent performances,giving full play to the characteristics of steel and concrete materials,and widely used in bridge construction.As an important part of steel-concrete composite structure,the fatigue damage of shear key will affect the service life and service performance of the structure,which has become a key problem to be solved urgently.In this paper,numerical simulation and theoretical analysis are combined to analyze the fatigue performance of composite structural shear bonds under different fatigue loads.Here are main research contents and results:(1)The relative literatures are referred on steel-mix the development and application of composite girder bridge,the fatigue of the shear key and fatigue study of basic theory and research status.The research method has been carried on the detailed introduction,comparison and analysis after the selection rule of Miner s-n curve of composite structures under the fatigue damage of bridge shear key quantity calculation and fatigue life evaluation.(2)Consulting the rules and regulations of the domestic and foreign highway bridge fatigue load model,this paper introduces the fatigue load model,the British BS5400 specification of highway bridge(AASHTO)fatigue load model,the European highway Bridges(Eurocode)five kinds of fatigue load model,the latest promulgated in 2015 "highway bridge steel structure design code"(JTG D64-2015)three types of fatigue load model and Dr Chen,zhejiang university through statistics of the measured data of different grade roads fatigue load model.According to the comparative analysis of the engineering background,five different fatigue load calculation models are selected.(3)Based on the engineering background of a steel-mixed composite bridge in Jiashan,Zhejiang,the Midas model of the whole bridge was established,and the section at the middle and middle spans of the bridge was determined to be the section with the most unfavorable force.As shear bond fatigue failure was mainly caused by shear stress,the finite element software ANSYS was used to establish a segment fine model starting from the support.The left support,1/4 span,middle and right support on the third i-steel cross section are selected as concerns.(4)Five kinds of standard fatigue car models were loaded,and the stress-time history data of each concern was obtained by using the transient dynamic analysis function of finite element software ANSYS.The equivalent stress amplitude was obtained according to the MATLAB program based on the principle of rain flow counting method,so as to calculate the fatigue damage degree and fatigue life.It is found that the fatigue life of concerns 1-1,2-2,3-3 and 4-4 is higher than the design life(100 years).Under the action of the same fatigue vehicle,the fatigue damage degree of concern 1-1 is close to that of concern 4-4,and the closer the concern is the support,the greater the fatigue damage degree will be.Under the action of different fatigue vehicles,the fatigue damage degree of each concern is the largest under the action of the fatigue vehicle established by the measured data,and the fatigue damage degree of the standard fatigue vehicle is directly related to the difference of the axle number,wheelbase and axle weight of the vehicle. |
PDF Full Text Request