The need for an analytical method that one can apply manually to estimate dynamic impact forces on railway tracks that occur because of varying track stiffness or track profile initiated a study to develop an analytical method named as the Bezgin Method. The advancement of this method presented in this paper includes an extension of a set of equations developed and introduced by the first author earlier as the Bezgin Equations using the proposed method and development of a new equation. In addition to track stiffness taken into consideration in the equations introduced earlier, the Extended Bezgin Equations presented in this paper take into account bogie stiffness, wheel spring stiffness, Hertzian contact stiffness, and a factor for damping. The new equation takes into account the effect of vertical wheel acceleration as a train transitions to a stiffer structure or transitions along an ascending track profile. The paper unites and applies these equations to estimate wheel forces that develop along stiffness transition zones by considering an array of train speeds for an array of track stiffness ratios and representative values for track profile deviations along the transitions. Final section of the paper includes elaborate finite element analyses of structural track models that involve transitions of soil supported ballasted railway tracks with concrete based ballasted tracks along various transition lengths and compares their estimates for dynamic impact force factors with those estimated by the Extended Bezgin Equations. The paper concludes with a discussion of the potential uses, benefits, and the value of the Bezgin Method for railway engineering.

This paper presents a new technique to estimate dynamic impact forces on railway tracks that develop because of variations in track profile. The approach presented uses a wavelet decomposition method to systematically define the irregular profile variation of a rough track length in relation to regular wavelet functions. These functions provide the regular profile variation parameters to estimate the dynamic impact forces using a new method proposed by Bezgin. This paper begins with an introduction of the proposed Bezgin Method and two equations developed by this method to estimate dynamic impact force factors that develop along descending track profiles, followed by the presentation of the wavelet decomposition method to represent the irregular variations in rough track profiles by wavelet functions. The paper then presents three case studies that involve track profile and stiffness measurements and track damage data collection along three railway tracks in the United Kingdom and continues with the applications of the wavelet decomposition method to the measured variations in the track profiles. The equations developed by the Bezgin Method then make use of the processed profile data to estimate the dynamic impact force factors along the railway tracks. The paper ends by correlating the estimated dynamic impact force factors to the damage data collected along the tracks and shows that there is a relation between the observed track damage and the estimated dynamic impact force factors. The proposed technique has, therefore, the potential applications to assess railway track conditions and forecast railway track damage.

Dynamic train wheel loads, which can be significantly greater than static loads, occur because of a variety of factors and unless they are properly considered in track structural design, significant unplanned maintenance and premature track failure may result. This is particularly so for traditional ballasted railways built on soft foundations, because although ballast lends itself to maintenance, it is often problematic and costly to repair damaged foundations. A novel rigorous analytical–numerical approach is described to predict and characterize, for the first time, the damage to which railway foundations can be subjected as a result of dynamic loads. The approach marries a sophisticated three-dimensional dynamic model of the train–track system incorporating vertical track quality, foundation soil distress models, statistical analysis methods, and results of field investigation. The resulting analyses demonstrate that the magnitudes and distributions of dynamic loads are a function of train speed and track quality, and that specific locations experience significantly higher amounts of damage, which can lead to a variety of track faults. The approach is illustrated via a study of a heavy haul railway line in China where the wheel loads and tonnage carried are set to increase significantly. Findings from the study suggest that the thickness of the ballasted layer would need to increase by over 20% to prevent premature foundation failure provided that the track is maintained in good condition, and by significantly more should the track condition be allowed to deteriorate.

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The applications of Carbon Fiber Reinforced Polymers (CFRP) in construction have been grown drastically in the last 20 years because of the wide range of advantages and benefits of using CFRP in buildings, bridges and other type of structures. Nowadays, it is used for retrofitting concrete, masonry, steel and timber structures to resist both static and dynamic loads. Since the cost of replacing an existing structure is far more expensive than using FRP materials to strengthen it, CFRP strengthening techniques seem to be cost effective and easy to implement. Numerous experimental and numerical studies have been conducted to investigate the flexural and shear performance of uncracked reinforced concrete (RC) members externally strengthened with CFRP laminates or strips. However, the most practical usage of CFRP is to retrofit sections that had already been cracked and in need of maintenance. The fact that there have been limited studies to investigate the behavior and performance of pre-cracked beams strengthened with CFRP systems necessitated new and further investigations. In this study, the flexural performance of cracked RC beams retrofitted with CFRP plates and epoxy injections are investigated. The results of the cracked beams are compared with two control beams, a virgin un-strengthened beam and an uncracked beam strengthened with a CFRP plate covering 90% of the beam’s span. Load-midspan deflections for these beams were generated and compared. It is observed that the retrofitted cracked beams displayed more strength than the control beam. The results presented herein can aid designers in establishing a better understanding of the flexural performance of pre-cracked beams and how to economically retrofit such structural members.