View/hide extracted text (may have errors)
SLAB TRACK "MASS-SPRING" SYSTEM Mirjana Tomičić-Torlaković1, Miodrag Budisa2, Vidan Rađen 3 1 Civil Engineering Faculty University of Belgrade, Bul. kralja Aleksandra 73, 11000 Belgrade, Serbia, mtomicic@grf.rs 2 Alpha Rail OpenTrack Consulting Inc, USA e-mail: opentrack.USA@gmail.com 3 „ Interkop“, Belgrade, Serbia e-mail: vidra@yahoo.com Abstract: Development of ballastless slab track structure with "mass-spring" system was started about 20 years ago and different kinds of those track systems have been successfully in use for urban transportation systems. By these systems under the slab the elastic elements are inserted to provide protection from bothersome vibration and noise. The present article explains the principal aspects of calculation verifications by means of simulation model for the selected type of "mass-spring" track system. 1. Introduction Rail traffic are an integral part of the public transportation systems in the central arias of many cities. The proximity to the neighboring buildings, the sensitivity of the population and the necessity to share the route with motor trafic are factors for track design and construction. Rail traffic causes vibrations that are mainly caused by rolling between the running wheel and the rails (direct structure borne noise) and propagate via superstructure and the tunnel through the ground into nearby buildings and can cause audible secondary air-borne noise. Railway tracks within urban environment have usually to fulfil certain reqirements concerning emission of noise and vibration. The decisive range of vibration is: 5 Hz to 20 Hz and of structure borne air noise is: 40 Hz to 80 Hz /3/. Comparisons between different possibilities concerning reduction of noise and vibration showed that measures at the railway superstructure itself are usually preferable from a technical and economic point of view. A wide variety of measures are available and effective tools for reducing structure borne noise at the source. These measures include the use of highly elastic pads for rail fasteners, ballast and sleeper mats, elastic supports for slab tracks of so-called "mass-spring" systems. Decisive parameter for vibration absorption is the natural frequency (eigen- frequency) of the selected superstructure system. 2. Types of "mass-spring" systems "Mass-spring" systems are used in applications where the isolation demands, in terms of structure-borne noise, are very high (Figure 1.). Over recent decades, a wide range of mass-spring systems have been developed. There are systems that use in-situ concrete or pre-fabricated concrete components, their combination, with or without a ballast bed. The type of chosen construction is a basic factor in the design of elastic supports for mass-spring systems. TRB 2012 Annual Meeting Paper revised from original submittal.
