To assess the dynamic behavior of monorail-bridge system, an innovative model of train-guideway interaction has been developed based on multibody dynamics and finite element simulation. A finite element model of guideway structure for a particular monorail system is built up using parametric design language, considering a specific length of straddle monorail line in three dimensions. Both straight and curved track geometries are modeled to simulate the actual bridge infrastructure. Flexible elements are adopted for the guideway beams consisting of reinforced concrete profiles to increase the accuracy of the numerical simulations in a more realistic way. The bridge model indeed, is simulated using a beam-frame structure of composite steel-concrete material. A multibody simulation of monorail vehicle is then introduced using the commercial multibody software MSC Adams. The three-dimensional multibody model of the monorail vehicle together with the bridge subassemblies is eventually implemented in multibody environment. The entire dynamic model of the vehicle-track system consists of all flexible and rigid body elements. Dynamic responses of the vehicle and bridge system are then extracted for different loading conditions. The proposed numerical model is validated using some dynamic simulation results of the system from the vehicle manufacturer in the selected case study. The model is further verified against several analytical and measurement results reported in the literature both for straight and curved track configurations. The result of dynamic simulations gives an overview about the dynamic forces and reactions that can appear in bridge structure due to the train movement.

This paper deals with the dynamic response of infinite double Euler-Bernoulli beam supported by elastic foundation with stochastic stiffness subjected to an oscillating moving load, which is the first research in relevant literature review. In this matter, equations of motion for double beam are formulated in a moving frame of reference. Moreover, by employing the first order perturbation theory and calculating contour integration, the response of double beam is obtained analytically and validated by a stochastic finite element model. Sensitivity analyses on the various parameters of closed form solution such as velocity, load frequency, coefficient of variation of soil foundation and rail and slab bending stiffness show the significant effect of load frequency on the dynamic response of the doubled beam. From practical point of view, the obtained results of the present study can be utilized efficiently in analysis and design of slab track systems. ;where, ω = Ω À vq. 576 S. MOHAMMADZADEH, M. ESMAEILI AND M. MEHRALI

Railway tracks are one of the most important national assets of many countries. The major part of the annual budget of railway companies concerns repairing, improving, and maintaining railway tracks, which is a challenge for railway managers. The logical method of repair and maintenance should take into account all the economic and technical aspects of the problem and proper management of track maintenance—without knowing the factors and parameters responsible for the track failure—quality control methods, and finally, the choice of the appropriate repair methods. Railway track geometry is the main factor that identifies the track behavior and condition. It is based on measuring the geometric parameters of the track determined by the track quality indices. The existing track quality indices mostly represent the geometrical condition of the railway track superstructure. In the past years, the effects of track bed stiffness on the track condition have been investigated. This paper investigates the railway track condition based on the railway track geometry parameters as well as the vertical track stiffness. A method for continuous measurement of track stiffness along a railway line is described and demonstrated. By measuring the track geometry parameters and stiffness, the superstructure and the substructure condition of the railway track are assessed. In addition, the relation between these data is investigated by using data mining techniques such as classification, decision tree, clustering, and dominant wavelength filtering. It is shown that filtering the data based on the dominant wavelength provides the best correlation between the track geometry in the vertical direction and stiffness.

The ladder track is a new type of an elastically supported vibration-reduction track system that has been applied to several urban railways. This paper is devoted to the investigation of dynamic behavior of a ladder track under an oscillating moving load. The track is represented by an infinite Timoshenko beam supported by a random elastic foundation. In this regard, equations of motion for the ladder track are developed in a moving frame of reference. In continuation, by employing perturbation theory and contour integration, the response of the ladder track is obtained analytically and its results are verified using the stochastic finite element method. Finally, using the verified model, a series of sensitivity analyses are accomplished on effecting parameters including velocity and load frequency.

No abstract