Dynamic analysis of railway track structure

Railways, which have an important role in transportation systems have been rapidly improvedespecially in the last 50 years. In accordance with the contemporary developments, such asincreased line capacity and increase in operating speeds and axle loads in rail transportation,the efficiency of this system has increased; but on the other side, these improvements havecaused some problems. The increase of axle loads and operating speeds not only cause theexcessive dynamic forces subjected to train-track system but can also cause the damages oftrain and track components by the repeated dynamic axle loads. All these factors havenegative effects on passenger safety and comfort and also cause increase in maintenancecosts. To minimize the possible problems, ballastless track alternatives and suitable designand track components for ballasted tracks have been still investigated.Because of their elastic properties, railway systems are subjected to excessive vibrations andforces due to high velocities and increased axle loads. Frequency spectrums of these forces,especially for the resonance vibrations, are important to be known. Since one or more of theforced vibration frequency coincides with the natural frequency of the system, resonancevibrations, which are destructive because of their magnitude may occur. Therefore, to preventresonance vibrations and undesirable problems; the dynamic behaviors of train and trackcomponents should be well-known, suitable dynamic models should be evaluated foralternative track structures and comprehensive dynamic analysis should be performed duringdesign stages.In this study, a research about ?Dynamic Analysis of Railway Track Structure? is presented.After a brief introduction given in the first section; the type of railway track structures andforces acting on track structure are primarily described and a general information about theextant studies associated with the vertical stability of railway track structure is given in thesecond section of this study. In the third section titled as ?Vibration Analysis?, expressionsabout vibration and vibration analysis for systems are generally defined. The fourth sectioncomprises the main contents of this study. In this section, dynamic properties of train-trackcomponents, dynamic problems that can occur within the train-track system, dynamic modelsfor train and track structure and solution techniques that can be used for necessary dynamicanalysis during design stages are examined. Also, analytical solutions calculated by frequencydomain method for the selected standard track model according to different track componentsare presented in Appendix 1. As a conclusion, general recommendations are presented to givean idea and a suggestion for future researches and studies.Keywords: Superstructure of railway, dynamic modeling of railway track, dynamic analysis,vibration, frequency domain, time domain.