The effect of end bearings on the dynamic behavior of Floating-Slab tracks with discrete Slab Units

Abstract

Floating-slab tracks are known as one of the most effective means for reducing ground-borne vibration from railways. For such tracks, the rails are sitting on the top of a slab which is supported via resilient elements (known as slab bearings) on the track bed. The heavy mass of the slab along with the soft resilient elements provide a low natural frequency and therefore provide vibration isolation for a wide range of frequencies. The slabs can be constructed using precast concrete units which results in periodic structure of the tracks. The dynamic behaviour of floating-slab tracks with discrete slab units is investigated and reported in the literature. The literature employs the periodic-structure theory to investigate the effect of discontinuity and periodicity to quantify the dynamic magnification of forces at the wheel-rail interface and, for more advanced models, the influence on ground-borne vibration. This paper builds on previous work in the literature to investigate a specific feature of slab tracks with discrete units that has not been considered in the literature. The paper investigates the effect of end bearings which are used to provide vertical restraint between consecutive slab units. The work considers a floating-slab track with discrete units under the action of a harmonic moving load. The paper develops a special periodic-structure model for this purpose. The model performs calculations in the frequency domain and makes use of the periodicity condition resulting from the use of unit slabs as well as that due to the nature of applied loading. The paper demonstrates the influence of vertical stiffness of end bearings and its effect on the dynamic responses of the tracks.