Transcript Document

Sponsored by Federal Railroad Administration, Office of Research and Development
Overview of FRA/Volpe Research
on Concrete Ties
International
Concrete Crosstie & Fastening
System Symposium
June 6-8, 2012
David Jeong
Hailing Yu
U.S. Department of Transportation
Research and Innovative Technology Administration
John A. Volpe National Transportation Systems Center
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Motivation for Research
•
Rail seat deterioration determined as probable cause of two Amtrak
derailments on curved track
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—
Home Valley, WA on April 3, 2005
Sprague, WA on January 28, 2006
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Widespread damage observed
on concrete ties on Northeast
Corridor and elsewhere
•
Service life of concrete ties
appears to be less than original
design life (50 years)
•
FRA has awarded several contracts via High-Speed Rail BAA to
conduct research on concrete tie performance
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Research Constituents
FRA Track Systems Research Program
• Volpe National Transportation Systems Center
• Transportation Technology Center, Inc.
FRA High-Speed Rail Broad Agency
Announcement (BAA) Program
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•
•
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University of Illinois – Urbana-Champaign
Kansas State University
Silica Fume Association
ENSCO
NDT Corporation
Other Stakeholders
• Amtrak and North American Railroads
• Concrete Tie Manufacturers
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FRA BAA Projects on Concrete Ties
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University of Illinois at Urbana-Champaign (UIUC)
“Improved Concrete Crossties and Fastening Systems for US High Speed Rail and Joint
Passenger/Freight Corridors”
•
Kansas State University (KSU)
“Quantifying Effect of Prestressing Steel and Concrete Variables in the Transfer Length in
Pretensioned Concrete Crossties”
•
Silica Fume Association (SFA)
“Development of Optimal High Performance Concrete Mixture to Address Concrete Tie Rail
Seat Deterioration”
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ENSCO
“Concrete Tie Machine Vision Inspection”
•
NDT Corporation
“Characterizing Damaged Concrete Ties with Nondestructive Pulse Velocity Measurements”
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Kansas State University (KSU)
“Freeze-Thaw Performance of Concrete Railroad Ties”
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Example of Coordination with BAA Projects
Untensioned and Tensioned
Pullout Tests
Pretensioned Concrete
Prism Tests
Kansas State University
Concrete Railroad Tie Under Load
Volpe Center
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Finite Element Modeling of Concrete Tie
Heterogeneity
Concrete Tie Supported by
Ballast and Subgrade
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Motivation for Analysis and Modeling
• Identify potential conditions for failure
• Provide guidance for testing
• Interpret test data
• Extrapolate test results for difficult-to-test
conditions
• Evaluate “what-if” scenarios
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Common Concrete Tie Failure Modes
Rail Seat Deterioration
Cracking Due
To Excessive
Tensile Force in
Anchorage Zone
Fastener Failure
Flexural Cracking
(Center-Binding)
Others:
• Environmental degradation (freeze-thaw)
• Alkali-Silica Reactivity
• Electrical Isolation Failure
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Photographs of Failures in Wood and Concrete Ties
Plate Cutting in Wood Ties
Rail Seat Deterioration in Concrete Ties
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Examples of Rail Seat Damage
Gage Side
Field Side
Triangular-shaped Damage
Abrasion due to Water Intrusion
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Building Block Approach
Full-scale Level
Test
Analysis
Component Level
Coupon Level
Correlation
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Framework for Analysis
Develop
Evaluation
Techniques
Design
“A”
Load
Case
Evaluate
Compare
Effectiveness
Of Designs
Design
“B”
Revise
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Development of Evaluation Techniques
Develop
Evaluation
Techniques
Modeling and Simulation
Activities
N
Experimental and Testing
Activities
Confirm
Y
Evaluate
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Establishing Credibility and Confidence
• Verification
— Credibility from understanding the mathematics
— Compare computed results to known solutions
• Validation
— Credibility from understanding the physics
— Compare computed results to experimental data
• Uncertainty Analysis
— Credibility from understanding the statistical evidence
— Quantify uncertainty and variability from all sources
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Example Applications
• Wood versus Concrete Ties
• Untensioned Pullout Tests
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Untensioned Pullout Test
Schematic of KSU Test
Finite Element Model
(Half-symmetry)
Reinforcement
Matrix
Steel tube
Interface
Pullout
direction
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Free Body Diagram of Wire Pullout
F(x)
2R
x
L
L-x
t(x)
2r
P
P
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Distributions of Slip, Force and Bond
2R
Slip, s(x)
Force, F(x)
Bond, t(x)
x
x
x
x
L
2r
s(0) = sF
s(L) = sL
F(0) = 0
F(L) = P
P
𝐿
𝐹 𝑥 =𝑃−
2𝜋𝑟𝜏 𝜉 𝑑𝜉
𝑥
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Analysis of Pullout Test
Two first-order differential equations
𝑑𝑠
= 𝛾𝐹(𝑥)
𝑑𝑥
𝑑𝐹
= 2𝜋𝑟𝜏[𝑠 𝑥 ]
𝑑𝑥
𝛾 = Relative compliance =
Prescribed Conditions
Calculated Outputs
1
1
+
𝐴𝐶 𝐸𝐶 𝐴𝑆 𝐸𝑆
Initial Value Problem
Two-point Boundary Value
Problem
𝑠 0 = 𝑠𝐹
𝑠 𝐿 = 𝑠𝐿
𝐹 0 =0
𝐹 0 =0
𝑠𝐿 = 𝑠(𝐿)
𝑠𝐹 = 𝑠(0)
𝑃 = 𝐹(𝐿)
𝑃 = 𝐹(𝐿)
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Direct and Inverse Analysis
GIVEN: Bond-slip Relation
t
GIVEN: Pullout Force vs.
Slip Curve
P
s
s
Input
Input
DIRECT ANALYSIS
INVERSE ANALYSIS
Output
Output
CALCULATE: Pullout Force
vs. Slip Curve
CALCULATE: Bond-slip
Relation
t
P
s
s
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Inverse Analysis of Untensioned Pullout Tests
Average Pullout Curves with 95%
Confidence Band
Bond-Slip Relations Derived from Inverse
Calculation
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Pullout Test Results and Direct Analysis Results
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Model Verification and Validation Process
Reality of
Interest
Quantification
Modeling
Validation
Mathematical
Model
Simulation
Implementation
Computer
Model
Verification
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Recent Volpe Publications
• H. Yu and D.Y. Jeong, “Railroad Tie Responses to
Directly Applied Rail Seat Loading in Ballasted Tracks:
A Computational Study,” JRC2012-74149, August 2012.
• B. Marquis et al., “Effect of Wheel/Rail Loads on
Concrete Tie Stresses and Rail Rollover,” RTDF201167025, September 2011.
• H. Yu et al., “Finite Element Modeling of Prestressed
Concrete Crossties with Ballast and Subgrade Support,”
DETC2011-47452, August 2011.
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