outline - university of nevada, reno · 2011-02-18 · 2 wide-base tire dual 1980 1982 2000 2002...
TRANSCRIPT
1
Impact of Wide-Base Tires on Pavement and Trucking Operation
Imad L. Al-QadiFounder Professor of EngineeringIllinois Center for Transportation
Outline• Current Knowledge of Wide-base Tire• Impact of “Old” Wide-base Tires on Pavements • Impact of Wide-base Tires on Trucking Operation• New Generation of Wide-base Tires• Analytical Considerations• Three-Dimensional Finite Element Model • Pavement Response Analysis• Summary and Future Research
Tire Development
Bias PlyBias Ply
??Wide Wide Base Base
SinglesSingles
EnergyEnergy
RadialRadial
2
Wide-base TireDual 1980 1982 2000
2002 2000275, 295
385 425 445/455 495445/455: North America, 495: European Union
Tire Dimension
1013427495/45R22.51155340445/65R22.51126308425/65R22.51071285385/65R22.5998329385/55R22.5Wide-base1059235295/80R22.5108520112R22.5105418411R22.5Dual (one tire)(mm)(mm)
Rim-DiameterContact WidthTire SizeTire Type
EUROPE
37.8297.86720455/55R22.537.8291.02720445/50R22.537.8160.07720275/80R22.5(kN)(mm)(kPa)
Axle loadContact WidthTire PressureTire Type
North America
Dual vs. Wide-Base Tires• Wide-base tires have been used in
Europe since the early 1980’s• In 1997, 65% of trailers in Germany
used wide-base tires• Earlier generation of wide-base tires
were proven more detrimental to flexible pavement systems than regular dual tires
3
Impact of Early Wide-Base Tire
• Early generations are 385/65R22.5, 425/65R22.5, and 445/65R22.5:–Required high inflation pressure (790 to
890kPa – smaller contact area).–Significantly increased pavement damage
compared to dual tires:• Damage ratios ranged between 1.31 and 4.30.
Christison et al. (1980)– In-field measured pavement responses– Conventional wide-base tire induces more
damage than dual-tire 1.2~1.8 times more fatigue damage
Akram et al. (1992)• Multi-Depth Deflectometer at a speed of 90km/h• Conventional wide-base tire
Pavement life reduced by a factor of 2.5~2.8 when wide-base tire is used
• Comparison between Dual and Wide-base Tires:• 11R22.5, 245/75R22.5
• 385/65R22.5, 425/65R22.5
• Testing speed: 58 km/hr
• Pavement Damage Evaluation:• 10 and 45% fatigue damage model (Finn et al.1986)
• Wide-base tire induces significantly more damage than dual tire (1.5 times more fatigue damage)
Sebaaly et al. (1989)
4
• Comparison between Dual and Wide-base Tires• 11R22.5, 265/70R19.5• 355/75R22.5, 385/65R22.5, 425/65R22.5• Test speed: 76 km/hr
• Pavement Damage Evaluation• Steering axle is the most detrimental• A drive axle equipped with wide-base tires is more
damaging than dual-tires by a factor of 2.3 ~ 4.0.
Huhtala et al. (1992)
Bonaquist et al. (1993)
• Comparison between dual and wide-base tires• 11R22.5• 425/65R22.5
• Pavement Damage Evaluation:• Wide-base tire induces significantly more damage
than dual tire: 3.5 times more fatigue damage1.9 times more rutting damage
Early Studies on Wide-base Tire
1.9 - 3.5 times more damageWide-base(425/65R22.5)
FHWA (1993)
1.5 times more damageWide-base (385, 425/65R22.5)
Penn State (1989)
Cost 334 (1997-2001)
Huhtala et al. (1992)
1.2 - 1.6 times more damageWide-base (445/65R22.5)
2.3 - 4.0 times more damageWide-base(385, 425/65R22.5)
Damage PotentialsWide-base Tires
•Other studies at Canada, Europe, South Africa, and UC Barkley
•Code: 445/50R22.5Tire width (mm)/ Tire aspect ratio(%)/ Radial ply (R)/ Rim diameter (in)
5
Dual vs. Wide-Base Tires• Earlier generation of wide-base tires were
detrimental to flexible pavement• A new generation of wide-base tires has recently
been introduced:Legalized in all states for 355.8kN GVW trucks16-18% wider than the first generation:
Makes use of a new crown architecture that allows wider widths at low aspect ratiosDesigned based on inch/width principle
More uniform tire-pavement contact stress:Reduced tire pressure (690kPa) at high loads (151kN)
Potential economic advantages to trucking industry
New vs. Old - Design
425/65R22.5 XZY
Unique Infini-CoilTM technology.¼ mile of continuous steel cable to
help eliminate casing growth
New Generation of Wide-Base Tires
0
200
400
600
800
1000
1200
1 2 3 4 5 6 7 8 9 10Rib Number
Stre
ss (k
Pa)
New Wide-base(445/50R22.5)Conventional Wide-base(425/65R22.5)Dual (drive)New wide-base (2nd size) 455/55R22.5
New verses Conventional Wide-base(Footprint width and Tire diameter)
200
220
240
260
280
300
320
340
360
380
400
385/65R22.5 425/65R22.5 445/65/R22.5 445/50R22.5
Tire Size
Con
tact
Pat
ch W
idth
(mm
)
1000
1050
1100
1150
1200
1250
1300
Tire
Dia
met
er(m
m)(New wide-base)(Conventional wide-base)
6
New Generation of Wide-Base TiresMeasured Contact Stress at
Pavement Surface – 445/50R22.5
Measured Contact Stress at Pavement Surface – 275/80R22.5
New Generation of Wide-Base Tires
702.71 730.92 707.55 684.98
896.03 883.29
0
200
400
600
800
1000
Dua
l Driv
e(2
75/8
0R22
.5)
Ste
er(2
75/8
0R22
.5)
New
Gen
erat
ion
Wid
eBas
e(4
45/5
0R22
.5)
New
Gen
erat
ion
Wid
eBas
e(4
55/5
5R22
.5)
Con
vent
iona
lW
ideB
ase
(385
/65R
22.5
)
Con
vent
iona
lW
ideB
ase
(445
/65R
22.5
)
Tire Dimension
Ave
rage
Con
tact
Stre
ss (K
pa)
Average Contact Stress at Pavement Surface
Why Wide-Base Tires NOW?• Substantial savings to truck freight
transportation:– Fuel economy– Increase hauling capacity (increase payload)– Reduced tire cost and repair– Ride and comfort– Reduced emission and noise– Reduced recycling impact of scrap tires– Better handling, braking, and safety
Impact on Road Infrastructure?
7
Unloaded - 8500 lb/axle
Unloaded - 8500 lb/axle
Loaded - 17000 lb/axle
Unloaded - 8500 lb/axle
Loaded - 17000 lb/axle
All footprints done exactly to0.4 : 1 Scale.
Loaded - 17000 lb/axle
At 60 mph (100 kmh), aerodynamic drag consumes approximately 40% of the fuel.Mechanical losses consume approximately 25% of the fuel. Rolling resistance accounts for approximately 35% of the fuel consumed.
aerodynamic drag
Where Does the Fuel Go?
mechanical losses
rolling resistance
Fuel Economy/ Hauling Capacity• Tire rolling resistance accounts for 35% of
truck energy consumption• Using the new generation of wide-base
tires reduces rolling by 12%:– Reduction fuel consumption by an average of
4%– Savings of fuel per year
• A truck that uses 6.5 mpg on duals will be at 6.76 mpg or better with new wide-base generation
• At 120,000 miles/year, the saving is 710 gallons (3230 liters) per vehicle per year
• Reduces truck weight by 410kg:– Increases haling capacity by 2%
8
Tire Cost and Repair, Truck Safety, and Ride Comfort
• Requires only one rim compared to two for dual tires
• Requires half the repair time needed for dual tires• Handling is maintained even when two tires blow
out– Requires regular monitoring of tire pressure
(good practice for all tire types)• Ride quality is improved by 12% compared to dual
tires
Environmental Impact
• Reduced gas emission: Reduction of 1.1 million metric tons of carbon equivalent by 2010 (assuming current market share, 5%)
• Reduce recycling impact of scrap tires:– 72.5kg of residual materials for dual tires vs.
53.6kg for a wide-base tire assembly.
95.6”
71.5”
0” offset
91.9”
74.6”
2” offset
Effect of Tires on Track Width
9
Implementation of Wide-base Tires in Canada!
Areas of Research• Dynamic impact of the tire (25% less
than dual tires?).• Recapping of wide-base tires vs. dual
tires• Impact on road Infrastructure
Cost 334 Action in Europe (1997~2001)• APT and instrumented pavement (17 tire
assemblies)• Intensive research on the effect of wide-base
tires– Tire type, axle load, tire pressure, and pavement
design• Pavement Damage Evaluation:
– Developed Tire Configuration Factor (TCF) by stepwise regression analysis
– Suggested the use of wide-base tires on the steering axle
– Top-down cracking was not considered
10
The COST Action (2001)
-3.1%1.47998380Wide (455/55R22.5)2.7%1.56947380Wide (445/50R22.5)----1.521054368Dual (275/80R22.5)
Wide-base vs. dualTCFD
mmW
mmTire Type
Primary Roads
• Introduced the concept of tire configuration factor (TCF):
81.085.068.1 )ratio.pres()198/length()470/width(TCF −−=
Al-Qadi et al. (2000-)• Heavily Instrumented Virginia Smart Road• Comparison between dual and wide-base tires
• 445/50R22.5, 455/55R22.5• Test parameters: speed, axle load, tire pressure
• Pavement Damage Evaluation:• Various transfer functions• Steering axle is the most detrimental• Wide-base is more fatigue damaging by a factor of 1.35.• Equivalent rutting damage • Wide-base is less damaging than dual in surface initiated
top-down cracking by a factor of 0.45
Prophète et al. (2003)• Instrumented Pavement: Laval University• Comparison between dual and wide-base tires
• 385/65R22.5, 455/55R22.5• 50km/hr, axle load, tire pressure• Wide-base (455) is more fatigue damaging by a factor of 1.54• Wide-base (455) is less rutting damaging by a factor of 0.17• Surface initiated top-down cracking is less damaging by 0.87
times
11
NCAT Experimental Study (2005)• Compared field responses of new generation of
wide-base tires to dual tires• Measurements conducted at 72.4km/h• Used measured strains at the bottom of HMA and
vertical stress on top of subgrade (reported rutting only)
• Both dual and wide-base tires configurations causes the same pavement damage
Current Knowledge of Wide-base Tire
More fatigue damage Similar rutting damage Less top-down cracking
New Gen. Wide-base Tire (445/50R22.5, 455/55R22.5)
Al-Qadi et al. (2003)
Less damage in rutting (0.17) and Top-down cracking (0.87)
New Gen. Wide-base Tire(455/55R22.5)
Prophète et al. (2003)
Cost 334 (1997-2001) 1.2 - 1.6 times more damageWide-base (445/65R22.5)
Damage PotentialsWide-base Tires
• Code: 445/50R22.5Tire width (mm)/ Tire aspect ratio(%)/ Radial ply (R)/ Rim diameter (in)
Impacts on Road Infrastructure• Only a few studies on new wide-base tire• What do we know:
– The steering axle is the most damaging – Significantly less damage than the first wide-base
tire generations– Impact on the subgrade is similar to dual tires– The layered theory can not be used to quantify tire
damage– Focus has been on primary roads
12
• Full-scale pavement testing at the Smart Road
• 12 different flexible pavement sections and a continuously reinforced concrete section.
• The flexible pavement sections were instrumented during construction with a complex array of pressure cells, strain gages, thermocouples, moisture probes, and frost probes.
Field Testing
Smart Road Pavement Design
A B C D E F G H I J K LOGFC
(19mm)SM-9.5D (19mm)
SM-9.5A (50mm)
SM-9.5A (50mm)
SM-9.5A (50mm)
BM-25.0 (225mm)
21B (75mm)
21B (75mm)
21B (75mm)
21A Cement
Stabilized (150mm)
Cement OGDL
(75mm)
21A Cement
Stabilized (150mm)
21A Cement
Stabilized (150mm)
OGDL (75mm)
OGDL (75mm)
21B (150mm)
21A Cement
Stabilized (150mm)
21B (175mm)
Cement OGDL
(75mm)
OGDL (75mm)
OGDL (75mm)
OGDL (75mm)
OGDL (75mm)
21B (175mm)
21B (175mm)
21B (175mm)
SM-12.5D (38mm)
SM-9.5D (38mm)
SM-9.5E (38mm)
SM-9.5A (38mm)
SM-9.5D (38mm)
SM-9.5D (38mm)
SM-9.5D (38mm)
SM-9.5D (38mm)
BM-25.0 (100mm)
SM-9.5A* (38mm)
SM-9.5D (38mm)
SMA-12.5 (38mm)
BM-25.0 (150mm)
BM-25.0 (100mm)
BM-25.0 (225mm)
21B (150mm)
BM-25.0 (100mm)BM-25.0
(150mm)BM-25.0 (150mm)
BM-25.0 (150mm)
BM-25.0 (150mm) BM-25.0
(225mm)
21A Cement
Stabilized (150mm)
21A Cement
Stabilized (150mm)
BM-25.0 (150mm)
21B (75mm)
21A Cement Stabilized (150mm)
21B (150mm)
21A Cement
Stabilized (150mm)
21A Cement
Stabilized (150mm)
21A Cement
Stabilized (150mm)
21B (75mm)
21A Cement
Stabilized (150mm)
CRCP
Concrete (250mm)
Cement OGDL
(75mm)
OGDL (75mm)
21B (150mm)
OGDL (75mm)
Modeled Section
Al-Qadi and Co-Workers• Testing at the Virginia Smart Road
(2000-2002):
13
Four speeds – 2 Load levels – 4 Tire Pressures
Longitudinal Strain
Transverse Strain
-400
-200
0
200
400
600
800
0 1 2 3 4 5
Time (sec)
μstra
in
-50
0
50
100
150
200
0 1 2 3 4 5
Time (sec)
μstra
in
0102030405060708090
100
8.0 24.1 40.2 72.4Speed (km/hr)
μstr
ain
SteeringDualWide Base
Field Evaluation
Tensile Strain under HMA
Vertical Stress under HMA
0
50
100
150
200
250
300
350
A C E F G H K LSection #
Stre
ss (k
Pa)
DualWide-BaseSteering
Conclusions of the Exp. Program• The steering axle is the most detrimental
of all tire configurations (small contact area with respect to the carried load)– Fatigue Failure: slightly greater for the wide-
base tire configuration– Subgrade Rutting: approximately equal for
the wide-base and dual tires configurations• Recommendation: Address a broader
range of failure mechanisms (i.e., HMA rutting, top-down cracking) using FEM.
14
Accelerated Loading Facility Testing
Loading matrix
0Dual, WB-455 & WB-425
80, 100 &1105, 106, 8, 10,
12 & 14
Offset(in)
Tire configuratio
n
Tire pressure(psi)
Speed(mph)
Tire load(kips)
Response testing (20 passes in each case)
Tire-pressure differential in dual tire (20 passes in each case)
0, 6 &-630, 50, 70 & 90110106, 10 & 14
Offset(in)
Variable tire pressure
(psi)
Control tire pressure
(psi)
Speed(mph)
Tire load(kips)
Full Depth HMA Test Sections
ThermocoupleStrain gauge
Section A Section B Section D Section FSMA – 2in
Poly. Binder 2.25in
Poly. Binder 2.25in
Standard Binder 3.5in
Standard Binder 2.5in
Rich Bottom Binder 4in
Lime Modified Subgrade 12in
DG Surface – 2in
Poly. Binder 2.25in
Poly. Binder 2.25in
Standard Binder 3.5in
Standard Binder 2.5in
Standard Binder – 4in
Lime Modified Subgrade 12in
DG Surface 2in
Poly. Binder 2.25in
Poly. Binder 2.25in
Standard Binder 3.5in
DG Surface 2in
Standard Binder 4in
Lime Modified Subgrade 12in
Lime Modified Subgrade 12in
15
Peak Response Ratio
Standard deviation
averageStandard deviation
averageStandard deviation
averageStandard deviation
average
1.19
1.28
Section A
0.05
0.05
1.12
1.19
Section B
0.04
0.05
0.081.180.061.18W455
0.081.310.091.26W445
Section FSection D
The ratio of measured peak longitudinal strain between wide-base tire and dual-tire assembly:
At 16km/h and various load and pressure levels:
dwlRR εε /=
Pavement Thickness Effect
Strain differences between dual-tire assembly and wide-base tire diminish as pavement thickness increases.
10 kips 100 psi at 10 mph
0
100
200
300
400
500
6 10 16HMA thickness (in)
Long
itudi
nal S
trai
n (M
icro
) DualWide base 455Wide base 425
10 kips 100 psi at 5 mph
0
100
200
300
400
500
6 10 16HMA thickness (in)
Long
itudi
nal S
trai
n (M
icro
) DualWide base 455Wide base 425
Load Effect
5 mph, 110 Psi
0
100
200
300
400
500
600
6 kips 8 kips 10 kips 12 kips 14 kips
Long
itudi
nal s
train
( μ)
DualWB455WB425
• Longitudinal strain at bottom of HMA linearly increases with load.
y = 27.284x + 35.423
y = 28.633x + 66.006y = 34.731x + 59.854
0
200
400
600
4 6 8 10 12 14 16
Load (kips)
Long
itudi
nal s
train
(mic
ro)
Dual-tire assemblyWide-base 455Wide-base 425
16
Tire position effect5 mph, 80 Psi
0
100
200
300
400
500
600
6 kips 8 kips 10 kips 12 kips 14 kips
Long
itudi
nal s
train
()
WB425_EdgeWB425
Strain under the low-pressure tire
0
100
200
300
400
30 psi 50 psi 70 psi 90 psi
Long
itudi
nal s
train
()
6 kips10 kips14 kips
Strain beneath the tires
0
100
200
300
400
500
30 psi 50 psi 70 psi 90 psi 110 psi
Long
itudi
nal s
train
()
6 kips10 kips14 kips
Strain under the high-pressure tire
0
100
200
300
400
500
30 psi 50 psi 70 psi 90 psi
Long
itudi
nal s
train
()
6 kips10 kips14 kips Control
tire (110 psi)
Variabletire
Experimental Findings• Ratios of longitudinal strain at bottom of HMA
between W-425 tire and dual-tire: 1.12-1.47; between W-455 tire and dual tires: 1.06-1.35 (at 16km/h).
• Higher strain ratios than smart road study, probably not considering reduction in dynamic forces induced by wide-base tires.
• The strain differences between dual-tire assembly and wide-base tire diminish as pavement thickness increases.
• Fatigue damage ratios between wide-base and dual tires is reduced when wander effect is considered. This effect diminishes for thick pavement.
17
Analytical Model • Uniform Pressure Distribution Model:
–Original models developed by Boussinesq (1885) and Burmister (1954),
–Uniform vertical pressure distribution–Circular areas
• Non-uniform Pressure Distribution Model–Nonuniform tire contact pressure model (Schapery, 1980)
–Distributions are actually non-uniform (Tielking, 1980)–Depends on the size and tire type (Roberts, 1987)
• Tensile strain at the bottom of HMA results in excess of 100% higher than those for uniform pressure
Drawbacks of Current Flexible Pavement Analysis
Vehicular loading:Stationary circularCan not differentiate between wide-base tires or dual tires (i.e., 385/65R22.5 = 455/55R22.5 and 11R22.5 = 12R22.5).
Pressure distribution:Uniform vertical contact stressNo surface tangential contact stresses
Effect of vehicle speed & loading:Pavement response to loading Is time-independent
Finite Element Approaches
Partial
Partial
Middle
Line loadStatic
2D Model
Highest intensityLowestComputational
time and memory
Static/DynamicStatic Loading
YesNoPavement
discontinuity
Interface modeling
Loading area
YesNo
VersatileCircular single
3D ModelAxisymmetric
Major Differences
Effective stiffnessTangent stiffnessStiffness
Equation of motionStatic equilibriumSystem equation
Relatively lowRelatively highResidual error
HighLowComputing intensity
Loading steps intensity
Loading Amplitude
HighLow
Time DependentConstant
Dynamic FEStatic FE
18
FE model for HMA
Layout of the 3-D FE model
Real and FE simulated tire foot prints for wide-base tire and dual tire assembly
Contact Pressure Loading
616k
pa
629k
Pa
703k
Pa
779k
Pa
840k
Pa
779k
Pa
702k
Pa
629k
Pa
616k
Pa
T1 T2 T3 T4 T5 T6 T7 T8 T9
532k
Pa
766k
Pa
867k
Pa
766k
Pa
532k
Pa
T1 T2 T3 T4 T5
532k
Pa
766k
Pa
867k
Pa
766k
Pa
532k
Pa
T5 T4 T3 T2 T1445/50R22.5
Dual Tires
Assigning pressure data to the FE of tire imprint
8kph XDA2- dual 6.9b_6.9bTread A B C D E F G H I J
ELEMENT Weight F for EL 6 Weight F for EL 8 0.641 0.872 0.988 0.858 0.641 0.641 0.872 0.988 0.858 0.64110 0.425 0.371 0.420 0.365 0.371 0.420 0.3659 0.488 0.752 0.313 0.656 0.743 0.645 0.313 0.313 0.656 0.743 0.645 0.3138 0.850 0.935 0.545 0.815 0.924 0.802 0.545 0.545 0.815 0.924 0.802 0.5457 0.975 0.985 0.625 0.859 0.973 0.845 0.625 0.625 0.859 0.973 0.845 0.6256 0.960 0.970 0.615 0.846 0.958 0.832 0.615 0.615 0.846 0.958 0.832 0.6155 0.805 0.898 0.516 0.783 0.887 0.770 0.516 0.516 0.783 0.887 0.770 0.5164 0.405 0.700 0.260 0.610 0.692 0.601 0.260 0.260 0.610 0.692 0.601 0.2603 0.327 0.285 0.323 0.281 0.285 0.323 0.28121
entrance
exit
455_new (7.2bar)_Final Tread A B C D E F G H IELEMENT Weight F for EL 7 Weight F for EL 8 Weight F for EL 9 0.500 0.830 0.884 0.940 0.956 0.940 0.884 0.830 0.500
10 0.500 0.476 0.415 0.442 0.447 0.455 0.447 0.442 0.4159 0.530 0.820 0.790 0.265 0.681 0.725 0.743 0.755 0.743 0.725 0.681 0.2658 0.858 0.940 0.915 0.429 0.780 0.831 0.860 0.875 0.860 0.831 0.780 0.4297 0.962 0.990 0.978 0.481 0.822 0.875 0.919 0.935 0.919 0.875 0.822 0.4816 1.000 0.990 1.000 0.500 0.822 0.875 0.940 0.956 0.940 0.875 0.822 0.5005 0.960 0.935 0.975 0.480 0.776 0.827 0.917 0.932 0.917 0.827 0.776 0.4804 0.845 0.810 0.910 0.423 0.672 0.716 0.855 0.870 0.855 0.716 0.672 0.4233 0.485 0.450 0.770 0.243 0.374 0.398 0.724 0.736 0.724 0.398 0.374 0.2432 0.420 0.395 0.402 0.3951
entrance
exit
• Dual tire
• Wide-base 455
19
Material Characterization• HMA materials: Linear viscoelastic
constitutive model– Indirect resilient modulus and creep
compliance– Prony Series Expansion
• Granular materials: Linear elastic constitutive model
– Nondestructive testing (FWD)
Creep Compliance Test at Different Loading Levels
-80
-40
0
40
80
120
160
0 0.05 0.1 0.15 0.2 0.25 0.3
Time (sec)
Tra
nsve
rse
Stra
in (m
icro
stra
in)
Transversal - T9
Longitudinal - T5
Pavement ResponseRetardation of the response
Asymmetry of the response
-75-50-25
0255075
100125150
0 0.1 0.2 0.3
Time (sec)
Long
itudi
nal S
trai
n ( μ
m/m
) MeasuredCalculated
20
Surface Strain (T=25°C)
-60
-40
-20
0
20
40
60
80
0 200 400 600
Distance(mm)
Tran
sver
se S
urfa
ce S
train
-80
-60
-40
-20
0
20
40
60
80
0.0 200.0 400.0 600.0 800.0
Distance(mm)
Tran
sver
se S
urfa
ce S
trai
n
Combined Relative Damage• Number of cycles till failure spread over
several orders of magnitude:– Rutting of HMA and top-down cracking are the
most critical distresses since they directly affect the pavement surface condition
........,...,)log(/1)log(/1)log(/1)log(/1
)log(/1
432
1
4321
===
+++=
+++=
−−−
−
−−−
aaaNNNN
Na
DRaDRaDRaDRaCombinedDR
fatiguesubgraderuttingdowntopHMArutting
HMArutting
subgraderuttingfatiguedowntopHMArutting
Al-Qadi and Co-Workers
A: Fatigue Cracking, B: Subgrade Rutting, C: HMA Rutting, D: Top-down
0.971.13
C
0.250.76
D
1.071.19
CDR
1.341.43
B
1.832.25
A
445/50R22.5455/55R22.5
DistressTire
• Combined Damage Ratios:
21
New Analysis Approach
Finite Element Modeling
Analysis ParametersMaterial Constitutive ModelsLoading AmplitudeSurface Shear Forces Layer Interface Condition
Validation of FE Models (w/ Field Measurements)
Pavement Damage Analysis
Model A
djustment
Discretization of Tire Imprint
A4
A3
A2
A1
A5
A6
A7
A8
Discretizationinto FE
One of the dual tire imprint
Finite elements
Loading Amplitudes
0.0
0.4
0.8
1.2
1.6
2.0
0 2 4 6Time Step
Am
plitu
de
Entrance Sideof Imprint
0.00.2
0.40.60.8
1.01.2
0 2 4 6Time Step
Am
plitu
de
Exit Side ofImprint
00.20.40.60.8
11.2
1 2 3 4 5Time (sec)
Am
plitu
de
Trapezoidal amplitudeAll tire-pavement contact stresses have same amplitude while moving.
Continuous amplitude for moving loadDifferent amplitudes for the entrance and exit part each rib.
22
Master curve for section “F”
1
10
100
1000
10000
1.E-03 1.E-01 1.E+01 1.E+03 1.E+05 1.E+07
Reduced Frequency, Hz
E*, k
si -10
4
20
Fit
Effect of Tire Loading
Interface FrictionSimple Friction Model: Friction Coefficient Control• Model characterized by the Coulomb friction
coefficient, μ• Resistance to movement is proportional to normal
pressure at interface
Elastic Slip Model: Max. Shear Stress Control• Shear stress and displacement are linearly
dependent until shear stress equals shear strength; then converted to the Coulomb friction condition
23
Measured vs. Calculated• Variation in interface friction coefficients• In case of elastic slip model, results are close to field measurement
5060708090
100110120130140150160170
1 0.7 0.5 0.2 Slip Measured
Friction Coefficient
Stra
in (m
icro
)
TransverseLongitudinal
• Conventional surface tangential pressure distributions(Pierre et al. 2003, Tielking 1987)
Stationary Moving
Surface Tangential Contact Pressures
Moving direction
Measured Tire Contact Stress
-0.20
0.10
0.40
0.70
1.00
0 100 200
Longitudinal Contact Points
Nor
mal
ized
Con
tact
Stre
sses
Vertical StressLongitudinal StressLateral Stress
Data not available
Entrance Aspect of Tire Imprint
Exit Aspect of Tire Imprint
Moving direction
24
Nonuniform Vertical Contact Stress
0
0.2
0.4
0.6
0.8
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16Data Points in a Rib
Nor
mal
ized
Ver
tical
Com
pres
sive
Str
ess
Rib 1 Rib 2 Rib 3 Rib 4 Rib 5
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28Data Points in a Rib
Nor
mal
ized
Ver
tical
C
ompr
essi
ve S
tres
s
Rib 1 Rib 2 Rib 3 Rib 4 Rib 5Rib 6 Rib 7 Rib 8 Rib 9
1
Asymmetric Transverse Tangential Stress
-1
-0.5
0
0.5
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Data Points in a Rib
Nor
mal
ized
Tra
nsve
rse
Tan
gent
ial S
tres
s
Rib 1 Rib 2 Rib 3 Rib 4 Rib 5
-1
-0.5
0
0.5
1
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28
Data Points in a Rib
Nor
mal
ized
Tra
nsve
rse
Tan
gent
ial S
tres
s
Rib 1 Rib 2 Rib 3 Rib 4 Rib 5 Rib 6 Rib 7 Rib 8 Rib 9
-8.E-04
-6.E-04
-4.E-04
-2.E-04
0.E+00
2.E-04
4.E-04
6.E-04
8.E-04
5000 5010 5020 5030 5040 5050
Tire Element Number
Surfa
ce T
ensi
le S
train
(µ)
Dual tire Widebase 455
-3.E-03
-2.E-03
-1.E-03
0.E+00
1.E-03
2.E-03
3.E-03
5000 5010 5020 5030 5040 5050
Tire Element Number
Sur
face
Ten
sile
Stra
in (µ
)
Dual tire Widebase 455
Without Surface Tangential Stresses
With Surface Tangential Stresses
Surface Tangential Stress Effect at Surface (40 oC)
25
Verification Results
-75
-50
-25
0
25
50
75
100
125
150
0 0.05 0.1 0.15 0.2 0.25
Time (sec)
Long
itudi
nal S
trai
n (µ
)
MeasuredCalculated-With Tangential PressureCalculated-Without Tangential Pressure
20
40
60
80
100
120
140
160
Without Shear With Shear Measured
Stra
in (m
icro
)
TransverseLongitudinal
Effects of Shear Forces
Various Dynamic Analysis ApproachesImplicit Dynamic Analysis
Advantage: Unconditionally Stable/ Very Small Error
Disadvantage: Long Analysis Time
Explicit Dynamic AnalysisAdvantage: Short Analysis Time
Disadvantage: Conditionally Stable/ High Error
Modal/Subspace Dynamic Analysis Only Applicable to the Linear Systems
26
-100
-50
0
50
100
150
200
250
0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045
Time (sec)
Long
itudi
nal S
train
(mic
rost
rain
)
T1
T2
T3
T4
T5
Dynamic Analysis Example with Impulsive Loading
It shows unreasonable strain oscillation at the bottom of HMA
-150
-100
-50
0
50
100
150
200
250
300
350
0.000 0.050 0.100 0.150 0.200 0.250 0.300 0.350 0.400 0.450
Time (sec)
Long
itudi
nal S
train
(mic
rost
rain
)
T1T2T3T4T5T6T7T8T9
Dynamic Analysis Example with Continuous Loading
Reasonable response at the bottom of HMA
Quasi Static vs. Dynamic Analysis
0
50
100
150
200
250
300
350
0.000 0.050 0.100 0.150 0.200 0.250Time(sec)
Tens
ile s
trai
n (μ
)
T1 T2 T3 T4 T5T6 T7 T8 T9
High Initial Strain
0
50
100
150
200
250
300
350
0.000 0.050 0.100 0.150 0.200 0.250Time(sec)
Tens
ile s
trai
n (μ
)
T1 T2 T3 T4 T5T6 T7 T8 T9
Smaller initial Strain
Peak Strain about 260 µ
Higher Peak Strain: 305 µ
Quasi-Static Visco Analysis
Implicit Dynamic Analysis
Interstate Pavement Design: 25v Degree 5 mph
27
Quasi Static vs. Dynamic AnalysisExtreme Case:
10 degree/50 MPH at bottom of 6 inch of HMA: Low Temperature
-60
-20
20
60
100
0 0.05 0.1 0.15
Time (sec)
Long
itudi
nal S
train
(µ)
ElasticQuasi-Static-ViscoImplicit Dynamic
Tensile strain at the bottom of HMA
0
50
100
150
200
250
300
Tens
ile s
train
(mic
ro)
Quasi-static
Dynamic
Tensile strain at thebottom of HMA
263.06 302.73
Quasi-static Dynamic
Quasi Static Response vs. Dynamic ResponseMaximum dynamic strain is higher than that of quasi-static analysis (about 15%)
Summary• Only a few studies on new wide-base tire• What do we know:
– The steering axle is the most damaging of all axles– Significantly less damage than the first generations– Impact on the fatigue is a little higher than dual tires
(depend on pavement structure)– Impact on rutting is similar to dual tires– Impact on surface cracking is less than dual tires– The layered theory with static circular loading is not
appropriate to quantify tire damage– Focus has been given to primary roads
28
??Overall Damage Ratio↑↓Top-Down Cracking↓↑Fatigue Cracking→→Secondary Rutting→→Primary Rutting
Road Infrastructure↑↓Tire Recycling↑↓Noise Reduction↑↓Gas Emission
Environmental Impacts↑↓Ride and Comfort→→Truck Operation and Safety↑↓Tire Cost and Repair↑↓Hauling Capacity↑↓Fuel Economy
Trucking Operations
Wide-base TiresDual TireCriterion