Study On Large Amplitude Of Canopy Structure Of High-speed Railway

When the train is running at high speed,the formed train wind will have a strong impact on the structure along the line.The platform canopy structure has the advantages of large span,small stiffness,located above the main line,and is greatly impacted by the train wind.Fatigue problems may occur under long-term vibration.During the longterm monitoring of the canopy structure of a platform,it is found that the purlin of the structure has a large vibration visible to the naked eye,and the amplitude peak to peak value of 30 mm,seriously affects the safety performance of the canopy structure.In this paper,the research is carried out from the aspects of train wind pressure load,structural fatigue,visual safety and structural reinforcement,in order to ensure the safe service of the canopy structure.Taking the canopy structure of the platform as the research object,firstly,the wind pressure load is determined according to the relevant specifications,which is set as the standard wind pressure;secondly,the monitored train wind pressure data are linearly fitted with the positive and negative peak values of the head wave and coda wave,and the wind pressure time curve equation related to the train speed is derived,which is set as the measured wind pressure.Then the finite element model of the platform canopy structure is established by using the ANSYS finite element software,and the dynamic analysis is carried out by applying the standard wind pressure and the measured wind pressure respectively,and the two analysis results are compared with the measured vibration displacement respectively.According to the stress results of finite element analysis under measured wind pressure,the fatigue problem of purlin is evaluated.Finally,with reference to the structural amplitude limit of visual safety,three strengthening schemes of canopy structure are proposed,which are enlarged crosssection reinforcement method,prestress reinforcement method and truss reinforcement method,and their ANSYS finite element analysis and comparison are carried out.The results show that the positive and negative peak values of the train front wave wind pressure are larger than the positive and negative peak values of the train wake wind pressure,respectively.The wind pressure time history curve equation and finite element model related to train speed are correct.The purlin structure meets the fatigue requirements of the code and will not occur fatigue failure,and it is proposed that the peak amplitude of visual safety is 16 mm.The three strengthening schemes have their own advantages and disadvantages,but the truss structure strengthening method is selected,in which the increasing section method is more effective;the prestressed structure reinforcement method is not very obvious because of the height restriction;the truss structure reinforcement method can effectively reduce the amplitude peak and peak value.This analysis can provide a reference for the determination of the train wind pressure on the related platform canopy structure,the fatigue analysis of the structure,the determination of the limit value of visual safety amplitude and the reinforcement of the structure.