Characterization of Vertical and Lateral Wheel Loads

Transcription

1 Characterization of Vertical and Lateral Wheel Loads 2014 Committee 30 Meeting Orlando, PA 14 October 2014 Andrew Scheppe, Riley Edwards, Marcus Dersch

2 Slide 2 Outline Method of Quantifying Loads Vertical Load Variation Lateral Load Variation Wheel Load Tables Conclusion

3 Slide 3 Overview of Mechanistic Design Design approach utilizing forces measured in track structure and properties of materials that will withstand or transfer them Uses responses (e.g. contact pressure, relative displacement) to optimize component geometry and materials requirements Based on measured and predicted response to load inputs that can be supplemented with practical experience Requires thorough understanding of load path and distribution Allows load factors to be used to include variability due to location and traffic composition Used in other engineering industries (e.g. pavement design, structural steel design, geotechnical)

4 Slide 4 Objectives Measure magnitude and distribution of wheel loads to be used as an input for mechanistic design Quantify variation due to: Car Type and Weight Speed Seasonal Variation Cant Deficiency Develop wheel load tables for use in design

5 Slide 5 Measurement Technologies

6 Slide 6 Vertical Wheel Load Measurement Wheel Impact Load Detectors (WILD) Sixteen sets of strain gauges to detect full rotation of most wheels For each wheel, Labels by vehicle type Measures speed, nominal (static) wheel load, and peak wheel load

7 Slide 7 Lateral Wheel Load Measurement Truck Performance Detectors (TPD) 6 cribs with strain gauges on the base and web of the rail For each wheel, Labels by vehicle type Measures peak vertical and lateral load

8 Slide 8 Vertical Load Variation

9 Percent Exceeded Vertical and Lateral Load Characterization Slide 9 Traffic Distribution Nominal Wheel Loads 100% 90% 80% 70% 60% 50% Empty Cars Freight Locomotives Intermodal Freight Cars Passenger Coaches Passenger Locomotives Other Freight Cars 40% 30% Loaded Cars 20% 10% 0% Source: Amtrak Edgewood, MD (November 2010) Nominal Vertical Load (kips)

10 Percent Exceeded Vertical and Lateral Load Characterization 100% Traffic Distribution Peak Wheel Loads Slide 10 90% 80% 70% 60% 50% 40% 30% 20% 10% Freight Locomotives Intermodal Freight Cars Passenger Coaches Passenger Locomotives Other Freight Cars 0% Source: Amtrak Edgewood, MD (November 2010) Peak Vertical Load (kips)

11 Slide 11 Vertical Load Variation - Speed

12 Percent Exceeding Vertical and Lateral Load Characterization Slide 12 Seasonal Variation of Freight Wheel Loads 100% 90% 80% 70% 60% 50% 40% April October January July 30% 20% 10% 0% Source: Union Pacific Gothenburg, NE (2010) Peak Vertical Load (kips) 10 kips 45 kn

13 Percent Exceeding Vertical and Lateral Load Characterization Slide 13 Seasonal Variation of Highest Freight Wheel Loads 0.5% 0.4% 0.3% 0.2% April October January July 0.1% 0.0% Peak Vertical Load (kips) Source: Union Pacific Gothenburg, NE (2010) 10 kips 45 kn

14 Slide 14 Lateral Load Variation

15 Slide 15 Variation According To Car Type and Weight Positive Negative Gauge Field

16 Slide 16 Speed High Rail

17 Slide 17 Speed Low Rail

18 Slide 18 Cant Deficiency Measure of the difference between equilibrium superelevation and actual superelevation Combines the effect of degree of curvature, speed, and superelevation h d = 2b 0 g v /D h t h d = cant deficiency (mm) 2b 0 = distance between contact patches on a wheel set (assumed 1500 mm) g = acceleration due to gravity (9.81 m/s 2 ) v = vehicle speed (m/s) D = degree of curvature h t = actual superelevation of curve (mm)

19 Slide 19 Cant Deficiency Low Rail

20 Slide 20 Cant Deficiency High Rail

21 Slide 21 High Rail vs. Low Rail

22 Slide 22 Design Vertical Wheel Loads (WILD) Nominal Load (kips) Car Type Mean 95% 97.5% 99.5% 100% Unloaded Freight Car Loaded Freight Car Intermodal Freight Car Freight Locomotive Passenger Locomotive Passenger Coach Peak Load (kips) Car Type Mean 95% 97.5% 99.5% 100% Unloaded Freight Car Loaded Freight Car Intermodal Freight Car Freight Locomotive Passenger Locomotive Passenger Coach

23 Slide 23 Design Vertical Wheel Loads (WILD) Nominal Load (kips) Car Type Mean 95% 97.5% 99.5% 100% Unloaded Freight Car Loaded Freight Car Intermodal Freight Car Freight Locomotive Passenger Locomotive Passenger Coach Peak Load (kips) Car Type Mean 95% 97.5% 99.5% 100% Unloaded Freight Car Loaded Freight Car Intermodal Freight Car Freight Locomotive Passenger Locomotive Passenger Coach

24 Slide 24 Design Lateral Wheel Loads (TPD) Lateral Load (kips) Car Type Mean 95% 97.5% 99.5% 100% (Max) Unloaded Freight Car Loaded Freight Car Intermodal Freight Car Freight Locomotive L/V Car Type Mean 95% 97.5% 99.5% 100% (Max) Unloaded Freight Car Loaded Freight Car Intermodal Freight Car Freight Locomotive Locomotives have higher lateral load than loaded freight cars due to poor curving characteristics L/V ratio is most critical for unloaded freight cars Near the danger threshold of 0.68 at 99.5% level

25 Slide 25 Conclusion Most significant predictor of vertical and lateral load is car type and weight Speed does not have a significant effect on the magnitude of vertical or lateral load Wayside technologies provide an accurate measure of wheel loads that can be used for design

26 Slide 26 Acknowledgements Funding for this research has been provided by: Federal Railroad Administration (FRA) National University Rail Center (NURail) 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 For assistance with research, lab work, and previous analysis: Zhengboyang Gao, Brandon Van Dyk, Brent Williams FRA Tie and Fastener BAA Industry Partners:

27 Andrew Scheppe Railroad Transportation and Engineering Center RailTEC Slide 27 Questions?