| In recent years,with the acceleration of urban traffic construction,noise pollution has become increasingly serious.Noise barrier is the main way to reduce and improve the environmental noise along urban roads and high-speed railways.In view of the simple vertical noise barrier,scholars in China and abroad have carried out a lot of research,and the main results are focused on the acoustic and dynamic characteristics.With the comprehensive extension of China ’s high-speed railway network,when the railway passes through areas with high noise requirements,the general vertical noise barrier can not meet the noise reduction requirements.At this time,the air tightness and sound insulation performance of the fully enclosed noise barrier structure came into being.However,the fully enclosed noise barrier has high structure,large span and large load,and there are few studies on the mechanical properties of fully enclosed noise barrier by scholars in China and abroad.The research object of this paper is the new Beijing-Xiong ’ an intercity railway Beiluodian village fully enclosed sound barrier project.Its design speed up to 350 km /h is still the first case at home and abroad,there is no systematic technical research for high-speed railway fully enclosed sound barrier.Therefore,this paper conducted 4million times of fatigue performance research on the column foot part with the most complex force of the fully enclosed noise barrier,and established a finite element model for fatigue analysis based on the test results.The fatigue performance of fully enclosed sound barrier steel column foot is discussed.The main research contents and results are as follows :(1)The finite element analysis software is used to establish a fully enclosed sound barrier model.According to the working conditions of the sound barrier,the load combination is carried out to analyze the stress of the sound barrier.The results show that in all parts of the fully enclosed sound barrier,the stress level of the column foot is the highest,the stress concentration occurs,and the stress is the most complex.(2)Two concrete pedestals and two steel column feet were designed and manufactured,and one of them was selected for 4 million fatigue tests of steel column feet.The displacement of steel column feet,the stress of steel column feet,the stress of concrete and U-bolts under different cyclic loading times and the dynamic stress time history curves of steel column feet,concrete and U-bolts under different cyclic loading times were obtained.Combined with the experimental phenomena of steel column foot,the fatigue performance of the structure was discussed.(3)The test shows that the steel column foot structure of fully enclosed noise barrier does not have obvious failure characteristics,and the structure is relatively complete,and the mechanical properties are maintained well.By analyzing the static data,the stress curves of different times are basically coincident compared with the corresponding relationship curve.The linear relationship between load and unloading curve is obvious,and the stiffness of steel column foot does not degenerate with the increase of cycle times,indicating that the mechanical characteristics of the structure under fatigue load have not changed.It is concluded that the dynamic strain change is consistent with the load change,which well reflects the elastic advantages of steel.The maximum strain(tension or compression)is roughly consistent with the strain value of the maximum load level in the static load process.The structure has a certain anti-fatigue performance.(4)The finite element analysis software is used to simulate and analyze the static load performance of the steel column foot of the fully enclosed sound barrier,and the stress nephograms of the steel column foot of the fully enclosed sound barrier,the concrete pedestal and the U-bolt are obtained.The stress distribution is roughly equivalent to the experimental results,and the reliability of the model is verified by comparing the simulation results and the experimental results.By comparing the simulation results and the experimental results,it is concluded that the stress level of most measuring points is roughly equivalent to the simulation results,the stress-thrust curve fitting is high,and the model is reasonable.It can be imported into FE-SAFE for fatigue analysis.(5)Based on the finite element static analysis results,according to the actual working conditions and test conditions of the fully enclosed sound barrier steel column foot,the fatigue load spectrum is established and the fatigue life analysis is carried out.The fatigue load spectrum of steel column foot and the S-N curve data of steel plate,U-shaped steel bar and concrete are defined in FE-SAFE.The fatigue life of steel column foot is calculated by the Principal stress : Morrow algorithm of fatigue algorithm.The fatigue analysis results were imported into ABAQUS to view the fatigue life analysis results.It can be seen from the life diagram that the steel column foot and U-shaped bolt did not appear compressive fatigue failure under 10 million fatigue loads,which met the requirements of durability and safety. |
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