1. 2. Week Review AASHTO2 وضع التوافق

AASHTO ... Prof. Dr. Eng. Shafik JendiaAASHTO ... Prof. Dr. Eng. Shafik Jendia

AASHTO Pavement DesignAASHTO Pavement Design

((Review)Review)

Lectures of Lectures of 11., ., 2 2 WeekWeek0707..09 09 . . 201320131414. . 0909. . 20132013

Prof. DR.Prof. DR. Eng. Shafik JendiaEng. Shafik Jendia

Islamic University of GazaIslamic University of Gaza


Standard & RegulationStandard & Regulation

AASHTOAASHTO GUIDE FORGUIDE FOR

Design of Design of PavementPavement

StructuresStructures


AASHTOAASHTO

AAmericanmericanAAssociation ofssociation ofSStatetateHHighway andighway andTTransportationransportationOOfficialsfficials

meansmeans


AASHTOAASHTO

IntroductionIntroduction

Overview Overview ((AASHTO AASHTO -- Guide)Guide)

Pavement Design RequirementsPavement Design Requirements


Overview Overview ((AASHTO AASHTO -- Guide)Guide)

Part I:Part I: Pavement Design Procedures and Pavement Design Procedures and Management PrinciplesManagement Principles

Part II: Part II: Pavement Design Procedures for New Pavement Design Procedures for New Construction or Reconstruction Construction or Reconstruction

Part III: Part III: Pavement Design Procedures for Pavement Design Procedures for Rehabilitation of Existing PavementsRehabilitation of Existing Pavements


Pavement Design Pavement Design RequirementsRequirements

Traffic Load Traffic Load

Bearing Capacity of Soil (Subgrade)Bearing Capacity of Soil (Subgrade)

Layer Material PropertiesLayer Material Properties

Environmental ConditionsEnvironmental Conditions


Design InputsDesign Inputs

Traffic Load ESAL (wTraffic Load ESAL (w1818 ))Reliability R (%) Reliability R (%) Overall Standard Deviation (SOverall Standard Deviation (Soo))Effictive Roadbed Soil Resilient Effictive Roadbed Soil Resilient Modulus MModulus Mrr ((ksi)ksi)Design Serviceability Loss Design Serviceability Loss PSIPSI


ProcedureProcedureDetermining the Structural Number Determining the Structural Number SNSN = = f (ESAL,f (ESAL, R, SR, Soo, Mr, , Mr, PSI)PSI)

Converting the Structural Number SN into Layer Converting the Structural Number SN into Layer Thicknesses Thicknesses SN = aSN = a11DD11 + m+ m22 aa22 DD22 + m+ m33 aa33 DD33Where:Where:aa11, a, a22, a, a33 = = layer coefficientslayer coefficients

DD11, D, D22, D, D33 = = actual thicknesses actual thicknesses (inch) (inch) mm22, m, m33 == drainage coefficientsdrainage coefficients


SN of Pavement LayersSN of Pavement Layers

SN1 for 1. Layer, SN2 for 1. Layer + 2. Layer, SN3 for 1. Layer + 2. Layer + 3. Layer


Design VariableDesign Variable(Traffic Load)(Traffic Load)

1. Traffic Count (Vehicles , Axles).

2. Classification of Axles (Single , Tandem, and/or Tridem).

3. Determination of Axles Weights.

4. Determination of Equivalency Factors.

5. Determination of ESAL (W18).

6. Calculation of Traffic Load (Design ESAL).

ProcedureProcedure

Design ESAL = wDesign ESAL = w1818 x Dx DDD x Dx DL L x x 365 365 x Fx Fgrothgroth


Determining the Equivalency Factors

Single Axle Tandem Axle



Single Axle

7,5 t ~ 17 kipsEF = 0,812

11,5 t ~ 25,5 kipsEF = 3,83



18 t ~ 40 kipsEF = 2,08

Tandem Axle


Example Example ((Calculation of ESAL)Calculation of ESAL)

WeightWeight 77,,5 5 tt(~(~17 17 kip)kip)

1111,,5 5 tt(~(~2525,,5 5 kip)kip)

77,,5 5 tt(~(~17 17 kip)kip)

18 18 tt(~(~40 40 kip)kip)

EFEF 00,,812812 33,,8383 00,,812812 22,,0808

TotalTotalESAL (wESAL (w1818))

00,,812 812 nn1 1 + + 33,,83 83 nn22n =n = number of axlesnumber of axles

++ 00,,812 812 nn1 1 + + 22,,08 08 nn22n =n = number of axlesnumber of axles

Truck factor Truck factor (TF)(TF)

00,,812812+ + 33,,83 83 == 44,,6464((Total Weight Total Weight 19 19 t)t)

00,,812 812 + + 22,,08 08 = = 22,,8989((Total Weight Total Weight 2525,,5 5 t)t)

TotalTotalESAL (wESAL (w1818) )

44,,64 64 NN1 1 N= number of vehicles N= number of vehicles

++ 22,,89 89 NN22N= number of vehicles N= number of vehicles


Design ESAL

Design ESAL = wDesign ESAL = w1818 x Dx DDD x Dx DL L x x 365 365 x Fx Fgrothgroth

Where:

DDDD == a directional distribution factora directional distribution factor

DDDD == ((00,,3 3 -- 00,,77))


........... ........... lane distribution factor lane distribution factor DLDL

DDLL = = a lane da lane distribution factortion factor


........... ........... groth factor groth factor FFGrothGroth


Reliability (R) & Standard Deviation (So)Reliability (R) & Standard Deviation (So)

Statistic ParametersCover the Uncertainty or Variability of the Design Inputs and Performance Prediction

(Traffic count, Axle Weights, Future Traffic, etc..)

For Asphalt Pavements (So = 0,35 0,50)

the larger (So) the larger SN and thicker is the Pavement.



Reliability Values Table

When R = R = 9595%%This means : the Probability of Failure Occuring = = 55%% :



(for this example) Increasing of R from 50% to 99.9% increases both req. SN and cost for Pavements by approximately 50%.


Resilient Modulus MResilient Modulus Mrr

Mr is the Modulus of Elasticity of soil or SubgradeIncreasing of Mr affects: Decreasing of SNMinimizing of costs


Determining of Resilient Modulus Mr


Correlationen between MCorrelationen between Mrr and other and other Soil PropertiesSoil Properties

Mr (psi) = 1500 x CBR


Design Serviceability Loss Design Serviceability Loss PSIPSI

PSI: Total Loss of ServiceabilityServiceabilityPSI = Pi PtWhereWhere Pi = Initial Serviceability Index = Pi = Initial Serviceability Index = 44,,22

Pt = Terminal Serviceability IndexPt = Terminal Serviceability Index= (= (22,,0 0 33,,00))

Major Factor Influencing the Influencing the Serviceability of a Serviceability of a Pavement are: Pavement are: Traffic, Age and Environment


Components of Components of PSIPSI

1. Due to Traffic


Components of Components of PSIPSI

2. Due to Soil or Subgrade


Total Loss PSI

Due to Traffic + Soil


Example: Calculation of SNExample: Calculation of SN

Given:Given:WW1818 == 5 5 xx101066

R = R = 95 95 %%So = So = 00..3535MMrr == 5000 5000 psi ~ psi ~ ((35 35 MN/mMN/m22))

PSI =PSI = 11,,99Required: Required: SNSN


Exaple: Calculation of SNExaple: Calculation of SN

SN = 5,0


Calculation of SN Calculation of SN by (Design Equation)by (Design Equation)

Where:

ZR = f (Reliability R)

Other Parameters are Known


Total thickness of PavementTotal thickness of Pavement((Layer Thicknesses)Layer Thicknesses)

SN = aSN = a11DD11 + m+ m22 aa22 DD22 + m+ m33 aa33 DD33

WhereWhereaa11, a, a22, a, a33 = = layer coefficientslayer coefficients

DD11, D, D22, D, D33 = = actual thicknessesactual thicknesses (inch)(inch)mm22, m, m33 == drainage coefficientsdrainage coefficients


layer coefficientslayer coefficients

11. . Asphalt Layers (aAsphalt Layers (a11))

aa1 1 = = 00,,40 40 00,,4444EE-- ModulModul>> 400 000 psi (>> 2800 MN/m2)



22. . Base Course (a2)

aa2 = = 00,,1414EE-- ModulModul== 30 000 psi (~~ 210 MN/m2)



33. . Sub Base (a3)

aa3 = = 00,,1111EE-- ModulModul== 14 500 psi (~~ 100 MN/m2)


Drainage CoefficientsDrainage Coefficients

Drainage Coefficients: Drainage Coefficients: Functions of Both Functions of Both -- ClimateClimate--Determined Moisture Conditions Determined Moisture Conditions -- MaterialMaterial--Related Drainage QualityRelated Drainage Quality

For Good Conditions of Material For Good Conditions of Material

mmii ==11


Relationship between Drainage Relationship between Drainage Coefficients and Base ThicknessCoefficients and Base Thickness


Example: Determining of Layer Example: Determining of Layer ThicknessesThicknesses

Given:Given:WW1818 == 5 105 1066

R = R = 95 95 %%So = So = 00..3535MMrr == 5000 5000 psi psi

PSI = PSI = 11,,99SN =SN = 55,,00Required: DRequired: D11,, DD22, D, D33



11. Solution . Solution ((Iteration) withIteration) withaa11 = = 00,,44 44 aa22 = = 00,,14 14 aa33 = = 00,,1111

mm2 2 = = 11,,0 0 mm3 3 = = 11,,00SN = SN = 00,,44 44 DD11 + + 00,,14 14 DD22 + + 00,,11 11 DD33

Using Minimum ThicknessUsing Minimum Thickness


Minimum Layer ThicknessMinimum Layer Thickness



11. Solution. Solution ((11. Iteration) . Iteration) aa11 = = 00,,44 44 aa22 = = 00,,14 14 aa33 = = 00,,1111

mm22 = = 11,,0 0 mm33 = = 11,,00SN = SN = 00,,44 44 DD11 + + 00,,14 14 DD22 + + 00,,11 11 DD33Using Minimum ThicknessUsing Minimum Thickness

SN =SN = 00,,44 44 DD11 + + 00,,14 14 DD22 + + 00,,11 11 DD3311. Trial:. Trial: DD11== 33,,5 5 inch ~ inch ~ 9 9 cm Dcm D22= D= D3 3 = = 6 6 inch ~ inch ~ 15 15 cm cm

SN =SN = 55,,0 0 > > 33,,0404



11. Solution. Solution ((22. Iteration). Iteration)aa11 = = 00,,44 44 aa22 = = 00,,14 14 aa33 = = 00,,1111

mm22 = = 11,,0 0 mm33 = = 11,,00SN = SN = 00,,44 44 DD11 + + 00,,14 14 DD22 + + 00,,11 11 DD33

22. Trial:. Trial: DD11= = 6 6 inch ~ inch ~ 15 15 cm Dcm D22= = 9 9 in ~ in ~ 23 23 cm Dcm D3 3 = = 10 10 inch ~ inch ~ 25 25 cm cm

SN =SN = 55,,0 0 = = 55,,0 0 OKOK



22. Solution . Solution ((Iteration with other Iteration with other layer coefficientslayer coefficients))aa11 = = 00,,4242 aa22 == 00,,12 12 aa33 = = 00,,1010

mm22 = = 11,,0 0 mm33 = = 11,,00SN = SN = 00,,44 44 DD11 + + 00,,14 14 DD22 + + 00,,11 11 DD33

33. Trial:. Trial: DD11= = 77,,2 2 in ~ in ~ 18 18 cm Dcm D22= = 8 8 in~in~2020cm Dcm D3 3 = = 12 12 in~ in~ 3030cm cm

55,,0 0 ~ ~ 55,,1818


33. Solution:. Solution: Determining of SNDetermining of SN11, SN, SN22

SN1 = 2,80

Determining of SN1

Mit E2 = 25000 PSI ~ 180 MN/m2


SNSN1 1 = = 22,,8 8 = a= a1 1 DD1 1 DD1 1 = = 22,,88/a/a1 1 = = 22,,88//00,,42 42 = = 66,,7 7 in =in =1717cmcm

= 2,80 ~ 17 cmAsphalt Layers E1 = 400 000 psi = 2800 MN/m2 a1=0,42


33. Solution:. Solution: Determining of SNDetermining of SN11, SN, SN22

SN2 = 3,70

Determining of SN2

Mit E3 = 13700 PSI ~ 100 MN/m2


= 2,80

~ 17 cm

Base Course E2 = 25 000 psi = 180 MN/m2 a2=0,12

~ 19 cm

= 3,70= 5,0

Sub Base E3 = 13 700 psi = 100 MN/m2a3=0,10 ~ 33 cm

Asphalt Layers E1 = 400 000 psi = 2800 MN/m2 a1=0,42

SNSN22 = = 33,,7 7 = SN= SN11+a+a22 DD22 DD22 = (= (33,,77--22,,88)/a)/a22 = = 00,,99//00,,1212== 77,,5 5 in =in =1919cmcm

SNSN33 = = 55,,0 0 = SN= SN22+a+a33 DD33 DD33= (= (55,,00--33,,77)/a)/a33 = = 11,,33//00,,1010== 13 13 in =in =33 33 cmcm

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