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Overview of FRA/Volpe Researchon Concrete Ties

Sponsored by Federal Railroad Administration, Office of Research and Development

U.S. Department of TransportationResearch and Innovative Technology AdministrationJohn A. Volpe National Transportation Systems Center

David JeongHailing Yu

InternationalConcrete Crosstie & FasteningSystem SymposiumJune 6-8, 2012

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Motivation for Research

• Rail seat deterioration determined as probable cause of two Amtrak derailments on curved track

— Home Valley, WA on April 3, 2005— Sprague, WA on January 28, 2006

• Widespread damage observed on concrete ties on Northeast Corridor and elsewhere

• Service life of concrete tiesappears to be less than originaldesign 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

• 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

• 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”

• ENSCO“Concrete Tie Machine Vision Inspection”

• NDT Corporation“Characterizing Damaged Concrete Ties with Nondestructive Pulse Velocity Measurements”

• Kansas State University (KSU)“Freeze-Thaw Performance of Concrete Railroad Ties”

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Example of Coordination with BAA Projects

Untensioned and TensionedPullout Tests

Pretensioned ConcretePrism Tests

Concrete Railroad Tie Under Load

Kansas State University Volpe Center

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Finite Element Modeling of Concrete Tie

Concrete Tie Supported byBallast and Subgrade

Heterogeneity

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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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Flexural Cracking(Center-Binding)

Rail Seat Deterioration Fastener Failure

Cracking DueTo Excessive

Tensile Force in Anchorage Zone

Common Concrete Tie Failure Modes

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

Test Analysis

Correlation

Full-scale Level

Component Level

Coupon LevelGENER

IC SP

ECIM

ENS

NON-GEN

ERIC

SPEC

IMEN

S CLOSED-FORM ANALYSES AND COM

PUTATIONAL MODELING

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Framework for Analysis

Design“A”

LoadCase Evaluate

CompareEffectiveness

Of Designs

DevelopEvaluationTechniques

Revise

Design“B”

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Modeling and SimulationActivities

Experimental and TestingActivities

Confirm

Evaluate

Y

N

DevelopEvaluationTechniques

Development of Evaluation Techniques

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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

Pulloutdirection

Reinforcement

Steel tube

Matrix

Interface

Schematic of KSU Test Finite Element Model(Half-symmetry)

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Free Body Diagram of Wire Pullout

x

2R

L

P

2r

L-x

F(x)

t(x)

P

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Distributions of Slip, Force and Bond

x x x

s(0) = sF

s(L) = sL

F(0) = 0F(L) = P

x

2R

L

P

2r

Slip, s(x) Force, F(x) Bond, t(x)

𝐹 (𝑥 )=𝑃 −∫𝑥

𝐿

2𝜋𝑟 𝜏 (𝜉 )𝑑𝜉

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Analysis of Pullout Test

Initial Value Problem Two-point Boundary Value Problem

Prescribed Conditions

Calculated Outputs

𝑠 (0 )=𝑠𝐹𝐹 (0 )=0

𝑠𝐿=𝑠 (𝐿)𝑃=𝐹 (𝐿)

𝑠𝐹=𝑠 (0)𝑃=𝐹 (𝐿)

Two first-order differential equations

𝑑𝑠𝑑𝑥=𝛾 𝐹 (𝑥)

𝑑𝐹𝑑𝑥=2𝜋𝑟 𝜏 [ 𝑠 (𝑥 )]

𝛾=Relative  compliance= 1𝐴𝐶 𝐸𝐶

+1

𝐴𝑆𝐸𝑆

𝑠 (𝐿 )=𝑠𝐿𝐹 (0 )=0

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Direct and Inverse AnalysisGIVEN: Bond-slip Relation

P

s

DIRECT ANALYSIS INVERSE ANALYSIS

CALCULATE: Pullout Force vs. Slip Curve

CALCULATE: Bond-slip Relation

GIVEN: Pullout Force vs. Slip Curve

t

s

Input Input

Output Output

P

s

t

s

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Inverse Analysis of Untensioned Pullout TestsBond-Slip Relations Derived from Inverse

CalculationAverage Pullout Curves with 95%

Confidence Band

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Pullout Test Results and Direct Analysis Results

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Model Verification and Validation Process

Reality of Interest

Mathematical Model

Computer Model

Validation

Verification

Quantification

Implementation

Modeling

Simulation

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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,” RTDF2011-67025, September 2011.

• H. Yu et al., “Finite Element Modeling of Prestressed Concrete Crossties with Ballast and Subgrade Support,” DETC2011-47452, August 2011.