Engineering Studies on Joint Bar Integrity: Part II — Finite Element Analyses

Abstract

This paper is the second in a two-part series describing research sponsored by the Federal Railroad Administration (FRA) to study the structural integrity of joint bars. In Part I, observations from field surveys of joint bar inspections conducted on revenue service track were presented [1]. In this paper, finite element analyses are described to examine the structural performance of rail joints under various loading and tie-ballast support conditions. The primary purpose of these analyses is to help interpret and understand the observations from the field surveys. Moreover, the finite element analyses described in this paper are applied to conduct comparative studies and to assess the relative effect of various factors on the structural response of jointed rail to applied loads. Such factors include: discrete tie support (i.e. supported joint versus suspended joint with varying spans between effective ties), bolt pattern (four versus six bolts), initial bolt tension, and easement. In addition, results are shown for 90 lb rail joined with long-toe angle bars compared to 136 lb rail joined with standard short-toe joint bars.

Potential for external reinforcement of insulated rail joints

“…The magnitude of FEA IRJ deflections is in agreement with previous research. 26,27 All FE models showed that the deflection of an SUS-IRJ varies depending on the support stiffness. They proved that the additional deflection in an IRJ compared to that of a reference rail is lower when the model includes uniform support stiffness along the rail length, whereas this increases with the degradation of the track underneath the joint.…”

“…for a suspended IRJ for various support conditions. 27 Finally, it was recently shown by a 2D vehicle-track model that the impact force P1 that mostly causes the track degradation due to the accordance of frequencies with those of the track is greatly influenced by the joint angle, the mass of the rail and the mass of the wheelsets, whereas the peak force P2 is mainly affected by the support stiffness at the joint angle apart from the mass of the wheelset and the railpad stiffness. 28 In the past, the track deflection for various wheel loads and track conditions has been measured.…”

“…IRJ displacements have been evaluated only by numerical models (1-4.5 mm for various track conditions). 26,27 There is no current literature that shows the effect of structural enhancement of the performance of rail joints by using numerical modelling of joints compared to plain track validated with accurately assessed field displacements.…”

Engineering Studies on Joint Bar Integrity: Part I — Field Surveys and Observed Failure Modes

“…Specifically, finite element analyses (FEA) are under development to help interpret the trends observed in field survey data. Moreover, FEA of bolted rail joints is the topic of the second paper in this two-part series [9]. …”

Fatigue Analysis of Rail-Head-to-Web Fillet at Bolted Rail Joint Under Various Impact Wheel Load Factors and Support Configurations

“…Those discontinuities can cause high wheel impact loads, which might lead to rail end batter, loosened bolts, deteriorated support condition, and excessive deflection. Such defects can potentially lead to the following failure modes: bolt-hole cracks, head-web separation, bent or broken bolts, and cracked or broken joint bars [4,5]. Figure 1.…”