Research On Structural Static And Dynamic Behaviors Of Straddle-Type Monorail Transportation System

Straddle-type monorail transportation has better ability of grade climbing and better adaptability to pass smaller radius of the curve, and it is particularly well suited to mountain cities that are more ups and downs on the ground.The technique of straddle-type monorail transportation, which is obviously different from the traditional steel wheel and steel rail transit system, has already been applied in Chongqing. The rail beam which will experience the wheel cyclic fatigue loads in the course of use is a bridge structure that bears load as well as guides the vehicles, so fatigue-resistant performance and carrying capacity are most important to the rail beam structure. The bogies' structure of monorail vehicles is unique. Some features of straddle-type monorail transportation system, such as the running and guiding mechanism, wheel-rail contact relationship and surface roughness of rail beam, differ from that of other rail transit systems, so the vehicle-bridge coupling vibration has also uniqueness, which affects the riding comfort of monorail vehicles. The special running structure's features of monorail vehicle decide that there is no traditional derailment phenomenon for monorail vehicles. Therefore riding comfort of passengers is the only important assessment indicator of the running performance for monorail vehicle. Based on summarizing and absorbing the achievements in the pioneer works, some research work on straddle-type monorail transportation which was first introduced into China has been done in the following:1,The systematic experimental researches on 22m PC rail straight beam and 20m PC rail curved beam including corresponding bearing supports of straddle-type monorail transportation system,are carried out in China for the first time. These experiments mainly include static bending and torsion tests, 3 millions times of bending fatigue tests at mid-span, 3 millions times of shearing fatigue tests at end face of beam, static-load cracking, recracking and destructive tests of the beam body. Meanwhile, based on the experimental results, some design and construction suggestions of PC rail beam system are put forward for the late works.2,According to the running structure's features of straddle-type monorail vehicle, the dynamic model of monorail vehicle with 15 DOFs is established and the corresponding motion equations of vehicle are deduced. The linear mechanics model of pneumatic tire of straddle-type monorail vehicle is set up. Side leaning angles of pneumatic tires are deduced, meanwhile the radial force, side leaning force, aligning moment on the running, steering and stabilizing tire, are derived, and longitudinal slide turning characteristic of the running tire is also taken into account. On the basis of these, a detailed deduction about wheel-rail interaction relationship between the bogies of monorail vehicle and rail beam is made. 3,An overview about railway track irregularity is made. Referring to power spectral density function of surface roughness of rail beam measured in Japanese literatures and the model of road surface roughness at home and abroad, the surface roughness of rail beam of straddle-type monorail transportation system and its mathematical description are studied. With the establishing of governing equations to vehicle-bridge system of straddle-type monorail transit, comparison and analysis about its numeric algorithm are made. Finally a compute program is also developed.4,Dynamic responses of rail beam in typical section of Chongqing straddle-type monorail transportation system are calculated. The calculation results of vehicle-bridge system are compared with field test results, and the correctness of the vehicle-bridge analysis theory and the computing program are partially validated. Then, considering the Z206-25 rail beam in typical section of Chongqing straddle-type monorail transportation system as standard beam and utilizing the computing program, the influence of some parameters on the dynamic responses of vehicle-bridge system is analyzed. These parameters include train speed, the span and the mass of rail beam, the condition of surface roughness of rail beam, the carrying capacity of monorail vehicle, the characteristics of the vehicle suspension system and pneumatic tire. And at the same time some regularity are acquired.5,Various different riding comfort assessment indexes of the steel wheel and steel rail transit system, such as common railway and urban rail transit, are summarized and analyzed. Based on above, research on the riding comfort evaluation index of straddle-type monorail vehicle is done. The extent of riding comfort of passengers and the smoothness of train motion are meanwhile employed to assess the comfort of passengers, and corresponding calculation method and assessment grade are also set up. According to above evaluation standards established, tests and assessments about the riding comfort of Chongqing straddle-type monorail vehicles are both carried out. Finally, comparison between the extent of riding comfort and the smoothness is made.