Reconsideration of Tyre- Pavement Input Parameters for the Structural Design of Flexible Pavements

Transcription

1 Reconsideration of Tyre- Pavement Input Parameters for the Structural Design of Flexible Pavements Morris De Beer, CSIR Built Environment South Africa Slide 1

2 Assumption of Tyre Loading - Pavement Design Modeling: - Circular; - Variable load; - Variable pressure, but UNIFORM: Tyre Loading, P (kn) Uniform Contact Stress, q (kpa) Slide 2

3 SOUTH AFRICAN MAJOR PAVED ROAD NETWORK ~ km Slide 3

4 7 700 km National Roads in SA of Freeway/Expressway standard 10 TH ICAP QUEBEC CITY AUGUST 2006 Slide 4

5 Slide 5

6 Slide 6

7 Truck Tire Inflation Pressure in South Africa: 25 % OF TYRE PRESSURE PER 50 kpa INTERVAL TYRE INFLATION PRESSURE (kpa) Van Vuuren (1974) De Beer (1995) ~ 20 % Increase in 20 Years Average: 620 kpa Average: 733 kpa c:/capsaf1.wmf Slide 7 FIGURE 1 AVERAGE MEASURED TYRE INFLATION PRESSURE DISTRIBUTIONS OF HEAVY VEHICLES (AXLE LOADS > kg) ON ROADS IN THE PROVINCE OF GAUTENG, SOUTH AFRICA

8 ROAD/ PAVEMENT DAMAGE Slide 8

9 Slide 9

10 Slide 10

11 ENVIRONMENTAL MOISTURE CHANGES - SHRINK AND SWELL ( Flapping of shoulder) Slide 11

12 Sectometer S. Eckens, 1928 Truck Tyres. 10 TH ICAP QUEBEC CITY AUGUST 2006 Modern Tyre science Slide 12

13 TYRE -NO LOAD TYRE- WITH LOAD Slide 13

14 HEAVY VEHICLE SIMULATOR (HVS) DUAL TEST TYRES (12R22.5) Slide 14

15 Side view of tyre APPLIED LOAD/STRESSES P/σ P/σ End view of tyre 10 TH ICAP QUEBEC CITY AUGUST 2006 Vertical, Longitudinal & Lateral 3D Contact Stresses Stress Rotation Surfacing: h 1, E 1, v 1 Pavement Response: Stresses & Strains Base Layer: h 2, E 2, v 2 Subbase Layer: h 3, E 3, v 3 Selected Layer: h 4, E 4, v 4 Slide 15 Subgrade/ Foundation: h 5, E 5, v 5

16 Vehicle-Tyre Tyre-Pavement Interaction: STRESS-IN-MOTION (SIM) Technology Since Slide 16

17 Stress In Motion (SIM) Technology The measurement of 3D tyre/pavement contact stresses from moving vehicles Slide 17

18 Heavy Vehicle Simulators (HVS) since 1970s Slide 18

19 Gautrans HVS Mark IV+ Slide 19

20 Stress-In In-Motion (SIM) MK II SYSTEM ( ) 1995) Slide 20

21 425 /65 R22.5 HVS TIRE ON SIM SYSTEM Slide 21

22 LOADS & STRESSES: SAE SIGN CONVENTION Tyre Rotation +X +Z +Y Slide 22

23 SIM TESTING USING THE HVS - DUAL LOADING 10 TH ICAP QUEBEC CITY AUGUST 2006 Slide 23

24 STRESS-IN IN-MOTION TESTING USING THE HVS Slide 24

25 Dual Tyre: 3D-Contact Stresses (Pressure) Stress Ratio: 10:3:1 Slide 25

26 Typical SIM 3D Data Sets -Variable loading: 3D Z,X,Y - Contact Stresses: Variable loads: 315/80 R22.5 Tire Slide 26

27 Slide 27

28 Slide 28

29 Slide 29

30 TYRE FINGER PRINTING : (HVS : SIM : 11R22.5 TYRE) LOAD Slide 30 INFLATION PRESSURE

31 315/80 R22.5 HVS Tyre: Overloaded Slide 31

32 Slide 32

33 Overloading on Tyres: Contact Patches: (square not circular) Slide 33

34 STRESS-IN IN-MOTION (SIM) TESTING ON N3 - FREEWAY Slide 34

35 Quad (full) SIM pad configuration at a typical weighbridge site on National Road 3 (N3), near Heidelberg in Gauteng Slide 35

36 In operation SIM N3-TCC. Slide 36

37 DAW 50 SCALE - National Road 3 (N3), near Heidelberg in Gauteng Slide 37

38 MULTI-DECK SCALE - National Road 3 (N3), near Heidelberg in Gauteng Slide 38

39 Quad (full) SIM pad configuration at a typical weighbridge site on National Road 3 (N3), near Heidelberg in Gauteng Slide 39

40 Quad (full) SIM pad configuration at a typical weighbridge site on National Road 3 (N3), near Heidelberg in Gauteng Slide 40

41 SIM Measurement: N Tanker Slide 41

42 In operation SIM N3 -TCC. Slide 42

43 Truck Classification 2-Axle: 11 3-Axle: 12 or Axle: 112 or 1111 or 121 or 22 5-Axle: 122 or or 1121 or 113 or Axle: 123 or or 1122 or or 1212 or Axle: 1222 or or Axle: 1223 or1232 or or Axle: 1223 or1232 or or % 2-Axle: 11 18% 3-Axle: 12 or 111 4% 7-Axle: 1222 or or % 6-Axle: 123 or or 1122 or or 1212 or % 4-Axle: 112 or 1111 or 121 or 22 3% 5-Axle: 122 or or 1121 or 113 or % Slide 43

44 Two Axle Truck Vertical Contact Stress - Foot Prints 10 TH ICAP QUEBEC CITY AUGUST 2006 Slide 44

45 Slide 45

46 Slide 46

47 Slide 47

48 Slide 48

49 Slide 49

50 Slide 50

51 Slide 51

52 Slide 52

53 STEERING AXLE TEST 765: NKR /10/2003- STEERING AXLE mm; Ton 203 mm; Ton Counts Across the SIM pads Slide 53

54 STEERING AXLE UNEQUAL LOADING TEST 009: KTD 904 GP 13/10/2003: AXLE mm; Ton 266 mm; Ton Counts Across the SIM pads Slide 54

55 REAR AXLE UNEQUAL LOADING TEST 009: KTD 904 GP 13/10/2003- REAR AXLE mm; Ton 325 mm; Ton 258 mm; Ton 227 mm; Ton Counts Across the SIM pads Slide 55

56 REAR AXLE UNEQUAL LOADING TEST 230: NKR /09/ mm; Ton; 303 mm; Ton; 257 mm; Ton; 254 mm; Ton; Counts Across the SIM pads Slide 56

57 TYRE barely in contact with surface mm; Ton TEST /10/2003: DDT235N AXLE mm; Ton 202 mm; Ton 194 mm; Ton Counts Across the SIM pads Slide 57

58 AXLE 2: MISSING TYRE!! TEST 765: NKR /10/2003 AXLE 2 10 TH ICAP QUEBEC CITY AUGUST mm; Ton 196 mm; Ton 195 mm; Ton Counts Across the SIM pads Slide 58

59 Footprint of an 8-8 Axle Truck - Figure 7 in Paper Slide 59

60 Vertical Contact Stress n Shape Slide 60

61 Vertical Contact Stress m Shape Slide 61

62 Vertical Stress Cumulative Frequency N Slide 62

63 GVM/GCM-SIM N3 TCC RESULT RATINGS 1 AND 2 (n = 2 297) [2 Sept - 17 Oct 2003] Slide TH ICAP QUEBEC CITY AUGUST Tonne 15 Tonne 29 Tonne Bin: Vehicle Mass: GVM/GCM [Tonne] Number of Trucks

64 Axle Load Distributions N H:\ICAP-2006 Summary N3 TCC-FINAL-4-B-ICAP-2006.xls TYRES-1-2 -Histogram-Paper (2) ALL TYRES MEASURED: n = (This Study) - N3 -TCC-2003 All Other Tyres Axle 1 Left Axle 1 Right 1600 All other Tyers: 1.9 Tonne Steering Tyres: 2.95 Tonne Number of Tyres Bin: Tyre Mass Weight [Tonne] Slide 64

65 LOAD COMPARISON FIELD WITH REAL TRUCKS N3 TCC - HEIDELBERG D:\ICAP-2006\[MODIFIED-2SEPT-17OCT-ICAP-2006.xls]Total Load-GVM-GCM- SIM vs MULTI-DECK STATIC AND DAW 50 at N3-TCC (Heidelberg) (GVM/GCM) STATIC (1861) DAW50 (1501) Line of Equality Linear (STATIC (1861)) Linear (DAW50 (1501)) STATIC & DAW 50 Scales (Tonne) STATIC = x SIM (n = 1 245), R 2 = 0.99; Std. Y-Error: 1.37 Tonne; Std. Error (Coef) : DAW 50 = x SIM (n = 1 245), R 2 = 0.99; Std Y-Error: 1.42 Tonne; Std. Error (Coef): SIM (Tonne) Slide 65

66 Tyre Inflation Pressure Distributions N H:\CAPSA04\[Tyre Inflation Pressure Information-MORTON-MDB- N3 TCC - SELECTED HEAVY VEHICLE (HV) TRUCK TYRE PRESSURE DATA (26 Feb March 2003) LEFT-FRONT-(225 tyres) RIGHT-FRONT-(225 tyres) REST-LEFT-(845) REST-RIGHT-(845) Normalised Frequency TYRE INFLATION PRESSURE (kpa) Slide 66

67 SIMPLIFIED LOADING SHAPES Load Radii: r i Load Radii: r s t ac Semi-Infinite Layer Strain Energy of Distortion C/L and Edge C/L Edge C/L Edge Case 1: n- shape Case 2: m- shape Slide 67

68 Slide 68

69 1 x Truck - 30 Tyres: 20 mm x 20 mm resolution 20k points SED under Steering Axle - Slide 69

70 50 mm AC layer Slide 70

71 1 x Truck - 30 Tyres: 1 mm x 1 mm resolution 500k points SED under Steering Axle - 50 mm AC layer Slide 71

72 Tools exist to incorporate complex stress conditions at surface Side view of tyre APPLIED LOAD/STRESSES P/σ P/σ End view of tyre Vertical, Longitudinal & Lateral 3D Contact Stresses Stress Rotation Surfacing: h 1, E 1, v 1 Pavement Response: Stresses & Strains Base Layer: h 2, E 2, v 2 Subbase Layer: h 3, E 3, v 3 Selected Layer: h 4, E 4, v 4 Slide 72 Subgrade/ Foundation: h 5, E 5, v 5

73 Thank you for your attention.. Slide 73

74 Trailer Slide 74

75 Example: 7 Axle EMPTY Truck (1:2:2:3) Note Variation in Vertical Contact Stresses on all 30 tyres Slide 75

76 Example: 7 Axle Truck (1:2:2:2) fully loaded with cement Note Contact Stresses on Steering Tyres Slide 76

77 Example: Passenger Bus (1:1:1) (FIGURE NOT TO SCALE) Slide 77

78 Example: 7 Axle Truck (1:2:2:2) Note the missing tyre Slide 78

79 UNIFORM: VERTICAL (NORMAL) STRESS, zz Slide 79 Single tyre load: 20 kn; 520 kpa

80 SIM: VERTICAL (EDGE) STRESS PROFILE, zz 10 TH ICAP QUEBEC CITY AUGUST 2006 Slide 80 Single tyre load: 50 kn; 620 kpa

81 Stress Response - Moving Tyre: MODELED TYRE REAL-TYRE (FEM) Slide 81

82 Finite Element Analysis (CSIR):Uniform vs Non-Uniform Stress UNIFORM SIM-1 SIM-2 SIM-3 Slide 82