Research On Vehicle-Induced Vibration Of A New Type Of Assembled Platform Canopy Integrated Structure For High Speed Railway

High speed railways have become an indispensable backbone in China’s modern transportation system due to their advantages such as fast operation speed,strong transportation capacity,good safety and comfort,and low-carbon environmental protection.As China’s prefabricated building enter the stage of comprehensive development,under the strong support of various information technologies and the accelerated pace of urbanization process,the digital production of prefabricated building is gradually accelerating,and the industry competitiveness is gradually strengthening.Under the combination of national advocacy and its advantages,it is bound to be vigorously developed in the future and become an important way of China’s building industrialization,which is the future development direction of China’s building structure.This article conducts vehicle induced vibration analysis on the integrated structure of a new prefabricated platform canopy for high-speed railways.The main research content is as follows.(1)Theoretical analysis of the mechanism and propagation law of environmental vibration caused by ground vehicles,induction and summary of the factors causing environmental vibration during train operation,and introduction of current research methods for environmental vibration;Summarize the evaluation indicators and standards for environmental vibration in various countries,compare and analyze the applicability and allowable values of each specification,select the evaluation standards suitable for this study,and lay the foundation for subsequent vibration response evaluation and vehicle induced vibration analysis under different model parameters.(2)The vibration analysis method of train platform coupling system is discussed.Based on the vehicle track coupling dynamics theory,the multi-body dynamics model of high-speed train and the flexible Orbiton subsystem are established.The difference of train dynamic load generated when the German track irregularity and the measured track irregularity of Hefei Wuhan high-speed railway are used as external excitation is calculated respectively,and the more reasonable track irregularity is selected as the input load of the finite element model,and calculate the fastener force based on the established driving conditions.Establish a three-dimensional model of the integrated structure of a new prefabricated platform canopy,provide a basis for analyzing the vibration characteristics of the structural system through eigenvalue calculation,and input the calculated fastener force into the finite element model of the integrated structure of soil pile platform canopy.(3)Conduct vehicle induced vibration analysis on the integrated structure of the new prefabricated platform canopy,compare and analyze the vibration acceleration of the main components of the platform canopy,including the platform,canopy columns,π-shaped beams,and canopy plates under different working conditions,and summarize and explore the different vibration responses and propagation laws at key positions caused by vehicle induced vibration under different working conditions.The maximum vibration acceleration is relatively small when driving on the arrival and departure tracks,with bidirectional driving greater than unidirectional driving at the same speed.When driving on the arrival and departure tracks and the main track simultaneously,it is relatively large.The areas with high vibration on the platform surface are within 3m from the edge of the platform on the driving side and in the middle of the canopy column.The top of the canopy column is greater than the middle of the column,and the overall variation trend of the vibration acceleration of theπ-shaped beam is in a"w"shape.The canopy plate is the closest to the driving side with the maximum vibration.(4)Conduct time-frequency analysis of vibration velocity and acceleration for the integrated structure of the new prefabricated platform canopy.The vibration velocity of each key point of the platform canopy under various working conditions is within the range of0.12～0.44mm/s,and the peak vibration frequency is mainly distributed in the low-frequency range of 0～10Hz;The vibration acceleration of each key point of the platform canopy under various working conditions is within the range of 0.78～7.39mm/s~2,and the peak vibration frequency during the operation of the arrival departure line,main line,arrival departure line,and main line is mainly distributed in the range of 0～5Hz,0～60Hz,and 0～100Hz,respectively.Evaluate the vibration and human comfort of the platform canopy structure,and calculate the weighted Z vibration acceleration level and divided frequency Z vibration level through one-third octave analysis.The vibration speed of the platform canopy structure under various working conditions is far less than the vibration speed limit of traffic vibration on the safety of the building structure,indicating that the structure is safe and reliable;The maximum values of Z vibration level and frequency division maximum vibration level under various working conditions are 58.9d B and 53.0d B respectively,both within the limit range,meeting the human comfort requirements for people waiting at the platform.(5)Conduct vehicle induced vibration analysis on the integrated structure of the new prefabricated platform canopy with different model parameters such as fastener stiffness,soil mass,and structural damping ratio.The vibration velocity at each key position of the platform canopy structure under different fastener stiffness is almost the same,and the vibration acceleration increases with the increase of fastener stiffness,with the maximum on the platform surface.The maximum Z vibration level of the platform surface under various working conditions with fastener stiffness of 6.6e7N/m,1e8N/m,and 2e8N/m is 59.3d B,60.0d B,and60.6d B,respectively;The vibration velocity and acceleration at key positions show a decreasing trend under different structural and soil damping ratios.When the structural and soil damping ratios are 0.03,0.05,and 0.07,the maximum vibration acceleration levels of the station platform under each working condition are 59.2d B,58.9d B,and 58.7d B,respectively.It can be seen that the vibration response of the structure under different model parameters is reasonable,providing a theoretical basis for the promotion of the new prefabricated platform canopy integrated structure through vehicle induced vibration.