Study On Vertical Vibration Of (25+35+25)m Continuous Concrete Beam With Medium And Low Speed Maglev Train

With the development of the social economy and the growth of population,rail transit industry of China has entered a new stage of construction.The maglev train,which has the advantages of comfort,safety,environmental friendly and good adaptability,has become an ideal means of transportation for people.The development of maglev transportation has broad prospects.At present,China is vigorously developing low-medium speed maglev technology,and has successively built a number of low-medium speed maglev test lines.In 2015,Changsha built the first maglev commercial operation line with independent intelectual property rights in China.At the end of 2017,maglev transportation line S1 was put into trial operation in Beijing,which indicates that China's medium and low-speed maglev development has entered a new stage.The vertical coupling vibration of the middle-low speed maglev train-bridge is studied based on the(25+35+25)m continuous beam of Changsha maglev project.Main research contents and achievements are as follows:(1)The design objectives of the levitation control system and the dynamic mechanism of the electromagnetic levitation are analyzed.The PID control based on the displacement-/velocity/acceleration feedback is used to establish a single electromagnet suspension physical model.The influence of the selection of feedback coefficient on the levitation effect is analyzed.The guidance and control principle of the floating electromagnet are discussed.(2)The vertical coupled vibration analysis model of maglev train-track beam was established including 12-DOF maglev vehicle model,bridge finite element model,levitation control system,and track irregularity excitation.The coupling vibration equation of maglev bridge was deduced.A simulation analysis program using MATLAB was programmed to carry out a detailed simulation analysis of the maglev bridge on Changsha maglev(25+35+25)m continuous beam,and the dynamic response values of continuous beam and vehicle were obtained.(3)Aiming at the field dynamic test of(25+35+25)m continuous beam of Changsha maglev line,the test overview,test plan and corresponding dynamic response evaluation index were introduced.The data of dynamic deflection,vibration amplitude,vibration acceleration and the vibration acceleration of vehicle are analyzed and combined with the test to verify the established vertical coupled vibration model.The results show that the simulated values are in good agreement with the measured values and the changing rules are consistent.The model is reliable.(4)Taking the(25+35+25)m continuous beam as the research object,the influence of parameters such as vehicle speed,vehicle weight,beam height and side span ratio on the vertical coupled vibration of train-continuous beam is analyzed.The results can provide reference for the design of high-speed bridges in low-speed maglev lines.