Technical Reports

Effect of Torsional Fastener Resistance on the Lateral Response of a Rail-Tie Structure

  • 01
  • Sep
  • 1979
AUTHOR: Arnold D. Kerr
OFFICE: RPD
REPORT NUMBER: FRA/ORD-78/35
SUBJECT: Tracks & Structures
KEYWORDS: Lateral Deformations of Track, Railroad Track Equations, Fastener Rigidity
ABSTRACT: The use of the classical beam bending equations for the analysis of the track response in the lateral plane is of questionable validity; when the used fasteners exhibit a noticeable torsional resistance. To remedy this situation, recently a variety of other track equations were proposed and used. The purpose of the present study is to establish the effect of fastener resistance on the lateral response of the rail-tie structure and also to determine whether a fourth order differential equation, which includes a rotational resistance term, is sufficiently accurate for describing its.lateral response. To achieve this aim deflection tests were conducted on a rail-tie structure with adjustable fastener rigidities, then this test-structure was analyzed using a fourth order equation with and without a rotational resistance term, and subsequently the analytical and tests results were compared. The test results revealed that with an increasing rotational resistance of the fasteners, the deviation of the test curves, from the case of zero fastener resistance, also increases; thus, the beam bending equation is not suitable, in general, for the analysis of the lateral track response. The comparison of the analytical and test result showed that the measured deflection shapes of the test structure, for a variety of fastener rigidities, agree closely with the deflection shapes obtained using a fourth order differential equation which includes a rotational resistance term, provided the coefficient of this additional term contains the effect of the fastener rigidity and the bending rigidity of the cross-ties.
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