Slide 1 Lateral and Vertical Load Path Summary of Field Results 214 International Crosstie & Fastening System Symposium Urbana, IL 3 June 214 Matthew Greve, Brent Williams, J. Riley Edwards, Marcus Dersch, and Ryan Kernes
Slide 2 Outline Motivation for Research Experimentation Overview Lateral Load Path Measurement Technology Tie-to-Tie Lateral Load Distribution Vertical Load Path Equipment Overview Effect of Lateral Load Conclusions Future Work
Slide 3 Motivation for Research Lateral Load: Lateral load path has not been successfully mapped and defined in previous research Lateral loads are believed to be a contributing factor to challenges associated with fastening system component failure modes Vertical Load: Rail seat pressure distribution is a contributing factor for four of five potential rail seat deterioration (RSD) mechanisms (Zeman, 21) Current design methodology assumes uniform load distribution, but actual load distribution is unknown
Slide 4 Defining the Vertical and Lateral Load Path Vertical Wheel Load Lateral Wheel Load Rail Bearing Forces Frictional Forces Clip Insulator Rail Pad Assembly Shoulder Concrete Crosstie
Field Experiment Program Objective: Analyze the distribution of forces through the fastening system and impact on components relative displacements Location: Transportation Technology Center (TTC) in Pueblo, CO High Tonnage Loop (HTL): 2 degree curve section with Safelok I fasteners Railroad Test Track (RTT): tangent section with Safelok I fasteners Example Instrumentation: - Linear potentiometers - Strain gauges - Lateral load evaluation devices - Matrix based tactile surface sensors - Loading: Track Loading Vehicle (TLV) and train consists (passenger and freight) were used to apply loads Slide 5 Transportation Technology Center (TTC) HT L RTT High Tonnage Loop (HTL)
Slide 6 Field Instrumentation Map 1 2 3 4 A B C E G H I 5 6 7 8 D F R T V X 9 1 11 12 P Q S U W Y Z 13 14 15 16 MBTSS Crosstie Vertical Displacement Rods Rail Displacement Fixture Rail Longitudinal Displacement/Strains Pad Assembly Longitudinal Displacement Pad Assembly Lateral Displacement Vertical Web Strains Vertical and Lateral Circuits Shoulder Beam Insert (Lateral Force) Crosstie Surface Strains Embedment Gages, Vertical Circuit, Clip Strains
Slide 7 Field Instrumentation Map (May 213) 1 2 3 4 A B C D E F G H I 5 6 7 8 9 1 11 12 P Q R S T U V W X Y Z 13 14 15 16 Rail Displacement Fixture Lateral Load Evaluation Device
Slide 8 Field Instrumentation Map (May 213) 1 2 3 4 A B C D E F G H I 5 6 7 8 9 1 11 12 P Q R S T U V W X Y Z 13 14 15 16 Global Crosstie Displacement Rods MBTSS
Slide 9 Load Input: Track Loading Vehicle (TLV) Modified railcar with instrumented wheelset on hydraulic actuators Can apply known and controlled loads to track structure L/V force ratio testing: Vertical loads ranging from to 4, lbs (178 kn) Lateral loads ranging from to 22, lbs (97.8 kn)
Slide 1 Purpose of Lateral Force Measurement Quantify lateral loading conditions to aid in the mechanistic design of fastening systems Quantifying forces acting on the insulator and shoulder Quantifying the distribution of lateral forces within fastening system components and interfaces e.g. Bearing on shoulder, frictional resistance from rail pad assembly or clip, etc. Understanding the causes of variation on lateral load distribution among adjacent crossties
Slide 11 Lateral Force Measurement Technology Lateral Load Evaluation Device (LLED) Original shoulder face is removed Insert designed as a beam and optimized to replace removed section and maintains original geometry Measures bending strain of beam under 4-point bending Measuring bending strain is a proven technique
Slide 12 6, Lateral Load Transfer 27 5, 4, 24 21 18 Force (lbf) 3, 2, 1, 15 12 9 6 3 Force (kn)
Slide 13 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 4 F 1, 6 3
Slide 14 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 8 F 1, 6 3
Slide 15 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 12 F 1, 6 3
Slide 16 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 16 F 1, 6 3
Slide 17 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 2 F 1, 6 3
Slide 18 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 4 F 1, 6 3
Slide 19 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 8 F 1, 6 3
Slide 2 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 12 F 1, 6 3
Slide 21 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 16 F 1, 6 3
Slide 22 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 2 F 1, 6 3
Slide 23 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 4 F 1, 6 3
Slide 24 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 8 F 1, 6 3
Slide 25 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 12 F 1, 6 3
Slide 26 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 16 F 1, 6 3
Slide 27 6, Lateral Load Transfer 27 5, 4, 24 21 18 4 Force (lbf) 3, 2, 15 12 9 Force (kn) 2 F 1, 6 3
Slide 28 Lateral Load Restraint Curved Track (High Rail), Passenger and Freight Runs 25, 15 2, 9 Force (lbf) 15, 1, 75 6 45 Force (kn) 5, 3 15 5 1 15 2 25 3 35 4 Speed (mph) FREIGHT CONSIST (Peak values) PASSENGER CONSIST (Peak values)
Slide 29 Lateral Load Restraint Curved Track (Low Rail), Passenger and Freight Runs 25, 15 2, 9 Force (lbf) 15, 1, 75 6 45 Force (kn) 5, 3 15 5 1 15 2 25 3 35 4 Speed (mph) FREIGHT CONSIST (Peak values) PASSENGER CONSIST (Peak values)
Effects of Lateral Fastening System Stiffness Slide 3 9, 8, S Lateral Force (lbf) 7, 6, 5, 4, 3, 2, 1, -.1.1.2.3.4 Displacement (in) E U Rail Seat Lateral Stiffness (lbf/in) Max. Force (lbf) S 192,498 7,828 E 155,369 5,582 U 146,322 4,632 A higher lateral stiffness leads to more load being carried by that particular rail seat
Purpose of Rail Seat Load Distribution Measurement Slide 31 Measure magnitude and distribution of pressure at the concrete crosstie rail seat Improve understanding of how loads from wheel/rail interface are transferred to rail seat Compare pressure distribution on rail seats: Under various loading scenarios Under various rail seat support conditions Under various stages of rail seat wear Identify regions of high pressure and quantify peak values
Slide 32 Rail Seat Pressure Sensor Installation Rail MBTSS Setup Pad/Abrasion Plate BoPET:.7 PTFE:.6 Sensor:.4 PTFE:.6 BoPET:.7 Gauge Field Matrix Based Tactile Surface Sensor Cast-in Shoulders Concrete Crosstie Concrete Crosstie
Slide 33 4 Rail Seat Load Concentration 1 2 3 4 A % Initial Contact Area 3: 1% 11: 1% 9 1 11 12 P Unloaded Increasing Pressure
Slide 34 4 Rail Seat Load Concentration 1 2 3 4 A 4 % Initial Contact Area 3: 11% 11: 1% 9 1 11 12 P Unloaded Increasing Pressure
Slide 35 4 Rail Seat Load Concentration 1 2 3 4 A 8 % Initial Contact Area 3: 11% 11: 11% 9 1 11 12 P Unloaded Increasing Pressure
Slide 36 4 Rail Seat Load Concentration 1 2 3 4 A 12 % Initial Contact Area 3: 11% 11: 11% 9 1 11 12 P Unloaded Increasing Pressure
Slide 37 4 Rail Seat Load Concentration 1 2 3 4 A 16 % Initial Contact Area 3: 84% 11: 79% 9 1 11 12 P Unloaded Increasing Pressure
Slide 38 4 Rail Seat Load Concentration 1 2 3 4 A 2 % Initial Contact Area 3: 62% 11: 58% 9 1 11 12 P Unloaded Increasing Pressure
Slide 39 TLV Varying Lateral Load at RTT 4, lb (178 kn) Vertical Load 12 9 1 2 11 3 12 4 P Percent of Initial Contact Area 1 8 6 4 2 1 2 3 4 A 9 1 11 12 P.1.2.3.4.5.6 L/V Force Ratio
Slide 4 TLV Varying Lateral Load at RTT 2, lb (88.9 kn) Vertical Load 12 9 1 2 11 3 12 4 P Percent of Initial Contact Area 1 8 6 4 2 1 2 3 4 A 9 1 11 12 P.1.2.3.4.5.6 L/V Force Ratio
Slide 41 Effect of L/V Force Ratio on Pressure Current design practice is to assume a uniformly distributed rail seat load, even under high L/V force ratios. Increased pressure changes abrasion characteristics Introduction of fines may concentrate load further causing local crushing 2,5 2, Maximum Pressure 17.24 13.79 Pressure (psi) 1,5 1, 5 Average Pressure Uniform Pressure 1.34 6.89 3.45 Pressure (MPa)...1.2.3.4.5 L/V Force Ratio (Constant 4, lb Vertical Load)
Slide 42 Lateral Force and Rail Seat Pressure Conclusions Lateral load Lateral loads appear to be primarily distributed among three crossties Lateral stiffness of the fastening system plays an important role in transferring the lateral load into the shoulder Lateral wheel load and lateral stiffness should be considered in crosstie and fastening system design Component demand (e.g. contact pressure) exceeds material limits Related to primary failure modes (e.g. shoulder-insulator wear, RSD) Rail seat load distribution Rail seat load distribution is highly non-uniform Rail base rotation at threshold L/V force ratio can lead to significant load concentration on field side of rail seat Average and maximum pressure are affected by reduction of contact area
Slide 43 Lateral load Future Work What are magnitudes under true field conditions? What are the effects of varying track geometry? How do various fastening system types alter the lateral load path? Rail seat load distribution Can we understand the effect of crosstie support conditions by controlling under-tie ballast stiffness? How are threshold L/V and vertical load related? Can we correlate load nonuniformity to RSD?
Slide 44 Acknowledgements FRA Tie and Fastener BAA Industry Partners: Funding for this research has been provided by the Amsted RPS / Amsted Rail, Inc. Association of American Railroads (AAR) Federal Railroad Administration (FRA) Industry Partnership and support has been provided by Union Pacific Railroad BNSF Railway National Railway Passenger Corporation (Amtrak) Amsted RPS / Amsted Rail, Inc. GIC Ingeniería y Construcción Hanson Professional Services, Inc. CXT Concrete Ties, Inc., LB Foster Company TTX Company UIUC Andrew Scheppe, Zachary Ehlers, Doug Capuder, Daniel Rivi, Marc Killion, Darold Marrow, and Timothy Prunkard
Slide 45 Matthew Greve Graduate Research Assistant greve1@illinois.edu Questions & Comments Brent Williams Manager of Field Experimentation bwillms3@illinois.edu