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Title:Track model for predicting dynamic responses of railroad bridge approaches
Author(s):Hou, Wenting
Director of Research:Tutumluer, Erol
Doctoral Committee Chair(s):Tutumluer, Erol
Doctoral Committee Member(s):Barkan, Christopher; Spencer, Billie; Huang, Hai; Mishra, Debakanta
Department / Program:Civil and Environmental Engineering
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Bridge approach
Track transition
Field instrumentation
Numerical modeling
Mitigation method
Track-train-bridge model
Abstract:This research study focused on the development of a novel train-track-bridge model that can analytically tackle the difficult problem of a railway track transition zone and effectively simulate the dynamic response of a bridge approach subjected to moving train loads. The scope of the research encompassed statistical field data analysis, analytical model derivation, algorithmic developments, as well as experimental validation for the track model to provide improved design and maintenance practices. The objective was to better understand governing mechanisms of bridge approach problems that occur near bridge abutments using a field validated train-track-bridge model, study problems associated with differential settlement, hanging ties, impact loads and various lack of support conditions, select mitigation methods for existing deficiencies, and as a result, formulate improved bridge approach designs. The first task in this PhD study involved identification of problematic track bridge approach locations that experienced recurring differential movements for field instrumentation, performance monitoring, and conducting field data collection and interpretation along the US Amtrak Northeast Corridor lines near Chester, Pennsylvania. Multidepth Deflectometers (MDDs) were installed at the selected bridge approaches to monitor individual layer deformations of track substructure layers. Besides MDDs, strain gauges were also mounted on the rail at the instrumented sites to measure vertical wheel loads applied during the passage of a train. Statistical analyses were conducted on the collected field data to quantify track transient response and performance trends at the studied bridge approaches. Field collected data indicated one significant problem occurring at the instrumented bridge approaches, also known as the “hanging crosstie” problem, which is caused by several sequential crossties near the bridge abutment experiencing lack-of-support. These crossties with gaps formed underneath undergo oscillatory motion as the dynamic loading from moving wheels push and pull these crossties through rail deformations. As a result, the nonuniform support conditions of the track substructure worsen drastically and can result in extremely high deformations including heave condition due to train passage. This dissertation developed a ballasted train-track-bridge model and an analytical solution scheme for both open track (regular track) and near bridge (with severe “hanging crosstie” problem) locations. The simulation results from the developed ballasted train-track-bridge model matched well with the deformation data collected from the field instrumentation to properly validate the analytical solution scheme. Then, using the field validated track model, various mitigation methods, including changing rail pad stiffness, ballast stiffness, subgrade stiffness, and crosstie spacing, applicable to track bridge approaches were studied and discussed. Furthermore, details on two successfully applied mitigation methods, namely, (i) converting an open deck bridge to ballasted deck bridge and (ii) installation of a new track panel consisting of approximately 30 concrete ties with Under Tie Pads (UTPs) at a bridge entrance on Amtrak’s Northeast Corridor high speed passenger lines, were presented.
Issue Date:2020-06-11
Rights Information:Copyright 2020 Wenting Hou
Date Available in IDEALS:2020-10-07
Date Deposited:2020-08

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