Load Characterization. Rigid Pavement Design Course Traffic Load Considerations Load Groups Lane Wander Load Configuration

Load Characterization

Rigid Pavement Design

Course

Traffic Load Considerations

Load Groups

Lane Wander

Load Configuration


Course

Single AxleLoad Groups

•10 – 12 kips•12 – 14 kips•14 – 16 kips•16 – 18 kips•18 – 20 kips•20 – 22 kips•22 – 24 kips•24 – 26 kips


Course

25

20

15

10

5

0-24 -18 -12 -6 0 6 12 18 24 30 36 42 48 54 60

10-4

10-5

10-6

10-7

10-8

Pavement Edge

Accumulation Fatigue Damage Distribution

Traffic Distribution

Design Load Position

D=12"

D=18"

t=10”k=100pci

Bituminous Shoulder P.C.C. Pavement

Acc

umul

ate

Fat

igue

Dam

age

Tra

ffic

Dis

trib

utio

n (%

)

Figure 8 Lateral Distribution Fatigue Damage Effects


Course

DowelBar

Subgrade

Critical Stress forMid Slab Loading

SlabThickness

Slab Length (L)

Single Axle Loading

Agg

Subbase

he

w

s

a

Traffi

c Lan

e

Should

erH

inge

Join

t

Hin

ge Jo

int

Do


Course

Design Load Stress

P

hs

2


Course

1 101 102 103 104 105 106 107 108 109

Load Applications To Failure, Nf

1.00

0.90

0.80

0.70

0.60

0.50

0.40

Str

ess/

Str

eng t

h (

R )

MeanPf = 0.5

Portland Cement Concrete Flexural Fatigue

HilsdorfKesler (Pf = .05)

PCAZ.M. Design Pf = 0.24

Figure 4.36. PCC Flexural Fatigue Data with Various Curves.


Course

d

x

xL/ , , d/

• Edge• Interior

• Single, dual, or dual tandem wheel loads

Load Configuration


Course

unbo

nded

or

bond

ed

Tandem

DualTridem

Tied or ExtendedShoulder

Do

W

L

slab

=

0 o

r f


Course

• Asphalt Institute

- used s/a

• FAA

(based on tire configuration)

Effort has always been to transform the actual multiple-wheel load into an equivalent loading system consisting of a single wheel.

ESWL: Equivalent Single Wheel Load (Design Position)

ESAL: Equivalent Single Axle Load

ESAR: Equivalent Single Axle Radius (Design Position)

s a- used s/ =

a


Course

Lane Wander


Course

Equivalent Damage Ratio (EDR)

0 5 10 15 20 25

0.5

0.4

0.3

0.2

0.1

0

Damage Ration

Shoulder Type Bituminous 10’ Tied 2’ Extended

Mean Distance D (in)


Course

1 101 102 103 104 105 106 107 108 109

1.00

0.90

0.80

0.70

0.60

0.50

0.40

Portland Cement Concrete Flexural Fatigue

LABKey: Kesler Raithby and Galloway Ballinger

Load Applications To Failure, Nf

Str

e ss /

Str

eng t

h (

R )

Log Nf = 17.61–17.61(R)Se = 1.40

Nf = 10 k1+k2r

FIELD

logN= 2.27(1/R)+0.056


Course

Cracking

Slabthickness

Subgrade

Subbase

PCC slab

Slab length

Single axle

Tandemaxle

STRT Tran

sver

se jo

int

Tran

sver

se jo

int


Course

Design Load Stress


Course

Load Equivalency Factors(based on fatigue damage)

2 18 i

i 1 2 i

2i i

i ii i2

k r -r1 2 18i

1 2 i

LogN =k k r

P =p π a

s P σσ = ; r = ;

h MORk k r

LEF = =10 ; i = load group ork k r

load configuration


Course

Dimensionless Stress Function

Edge Condition

Axle Type

n Coefficients

a b c

Free SA 2 -0.0605 0.5571 -0.025

TA 4 0.6475 0.3501 -0.0161

Extended Lane

SA 2 -0.361 0.45 -2.07x10-2

TA 4 0.5983 0.1506 -0.00123

2 2

; n = # of load positions/axles;

P = Axle Load

hs a b c

Pa an


Course

Dimensionless Stress FunctionInt 8.0 3.5Edge 8.0 5.0Corner 5.0 4.0

a+bx+cx2S

/ , a 2 2 2

o eD hσh δk q a L w s t Agg, , , , , , , , ,

p p p Kf


Course

Equivalent Damage Ratio

a-

2

FE

Single Axle

D Free Edge: EDR = 0.39-0.526e -0.095Ln

1 1 Ext. Drv. Lane: = 4.29+0.03 24.32

EDR

Tied Shoulder: EDR=EDR 1 ExDrLnShld

FE

aLn D

Da Ln

EDRLTE

EDR

1


Course


a

0.184-4.654 5.768a

Ln

2

FE

Tandem Axle

Free Edge: EDR = e

1 Ext. Drv. Lane: EDR = 4.29+0.03 24.32

Tied Shoulder: EDR=EDR 1

D

ExDrLnShld

FE

aLn D

Da Ln

EDRLTE

EDR

1


Course


3

2

FE

Tridem Axle

a D Free Edge: EDR = -0.21+0.693 -0.154Ln

1 Ext. Drv. Lane: = 15.206+0.1085 487.21

EDR

Tied Shoulder: EDR=EDR 1 ExDrLnShld

FE

aLn D

a

EDRLTE

EDR

1


Course

SA, TA, or Tridem Axle Loaded Radius, ai

SA, TA, or Tridem Axle Loaded Radius, ai

% A

DT

Les

s T

han

a0= 1 - % Trucks

b0 = % Legal Axles + a0

a0

b0

Maximum Limit

Lower Limit

Upper Limit

aL aU aM

% A

DT

%

i

d ADT

da

% Trucks•% SA•% TA•% TridemAlso:•% Legal Axles = b0 – a0

•% Illegal Axles = %Trucks – b0 + a0

ii

Pa

p

% Trucks

% ADT = a + b(ai) + c(ai)2

Aj

Traffic Model


Course

ADTj from Pi+1 to Pi = 1, ,

%% %

2 j i j i j

TrucksADT LD A ADT ADT per Axle Type (j) per Day

ESALi (Ni)

3

1, ,1

3

1, ,1

%% %

2

% %

i j i j j j ij

T i j i j j j ij

TrucksADT LD ADT ADT A ELC LEF

V ADT ADT A ELC LEF

per Load Group (i) per Day

% Trucks (Aj) ELCj

%SA 1.0

%TA

%Tridem

210 SA TAk r r

210 SA Tridemk r r

i = Load Groupj = Load Configuration (Axle Type)ELCj = Equivalent Load Conversion FactorLEF = Load Equivalency Factor relative to single axle load groups (x)

Design ESAL (N) = ESALi •EDR (Correction for load group, load configuration, and lane wander)

Traffic Model

210 SA xk r r


Course

Traffic Model(per load configuration)

2

0 00

0 0

0 0

2

%

2

2

2 2

j j j

j

j j j j j j

j j j

u m ut

m

t

t

t u m u l m l

ADT a b a c a

a ba b a a a

a

ab b a

a

a bc

a

a a a a a a a

Documents

Load Characterization. Rigid Pavement Design Course Traffic Load Considerations Load Groups Lane Wander Load Configuration