Overview of FRA/Volpe Research on Concrete Ties

1. Sponsored by Federal Railroad Administration, Office of Research and Development Overview of FRA/Volpe Research on Concrete Ties U.S. Department of Transportation Research and Innovative Technology Administration John A. Volpe National Transportation Systems Center International Concrete Crosstie & Fastening System Symposium June 6-8, 2012 David Jeong Hailing Yu

2. 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 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

3. Research Constituents

4. 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”

5. Example of Coordination with BAA Projects Untensioned and Tensioned Pullout Tests Pretensioned Concrete Prism Tests Concrete Railroad Tie Under Load Kansas State University Volpe Center

6. Finite Element Modeling of Concrete Tie Concrete Tie Supported by Ballast and Subgrade Heterogeneity

7. 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

8. Common Concrete Tie Failure Modes Rail Seat Deterioration Fastener Failure Cracking Due To Excessive Tensile Force in Anchorage Zone Flexural Cracking (Center-Binding) • Others: • Environmental degradation (freeze-thaw) • Alkali-Silica Reactivity • Electrical Isolation Failure

9. Photographs of Failures in Wood and Concrete Ties Plate Cutting in Wood Ties Rail Seat Deterioration in Concrete Ties

10. Examples of Rail Seat Damage Field Side Gage Side Triangular-shaped Damage Abrasion due to Water Intrusion

11. Building Block Approach • Full-scale Level NON-GENERIC SPECIMENS Test Analysis • Component Level CLOSED-FORM ANALYSES AND COMPUTATIONAL MODELING • Coupon Level GENERIC SPECIMENS Correlation

12. Framework for Analysis Develop Evaluation Techniques Design “A” Compare Effectiveness Of Designs Evaluate Load Case Design “B” Revise

13. Development of Evaluation Techniques Develop Evaluation Techniques Modeling and Simulation Activities Experimental and Testing Activities Confirm N Y Evaluate

14. 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

15. Example Applications • Wood versus Concrete Ties • Untensioned Pullout Tests

16. Untensioned Pullout Test Schematic of KSU Test Finite Element Model (Half-symmetry) Reinforcement Matrix Steel tube Interface Pullout direction

17. Free Body Diagram of Wire Pullout F(x) 2R x L-x L t(x) 2r P P

18. Distributions of Slip, Force and Bond 2R Force, F(x) Bond, t(x) Slip, s(x) x L x x x 2r F(0) = 0 F(L) = P s(0) = sF s(L) = sL P

19. Analysis of Pullout Test Two first-order differential equations

20. Direct and Inverse Analysis GIVEN: Bond-slip Relation GIVEN: Pullout Force vs. Slip Curve t t P P s s s s Input Input DIRECT ANALYSIS INVERSE ANALYSIS Output Output CALCULATE: Bond-slip Relation CALCULATE: Pullout Force vs. Slip Curve

21. Inverse Analysis of Untensioned Pullout Tests Average Pullout Curves with 95% Confidence Band Bond-Slip Relations Derived from Inverse Calculation

22. Pullout Test Results and Direct Analysis Results

23. Model Verification and Validation Process • Reality of Interest Quantification Modeling • Mathematical Model Simulation Validation Implementation • Computer Model Verification

24. 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.