CE 452 Design of Airfield Pavement ? Â· CE 452 Design of Airfield Pavement I Slides based on materials prepared by Prof Jie Han, ... Jointing of Reinforced Rigid Pavements. Spreadsheet

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  • CE 452Design of Airfield Pavement I

    Slides based on materials prepared by Prof Jie Han, University of Kansas, USA

  • 2

    OutlineIntroductionBasic principlesRigid pavement designFAA method

  • Airfield vs. Highway Pavements

    Repetition of load

    Distribution of traffic

    Geometry of the pavement

    Affected by pavement width and type of aircraft

  • Plan View of Basic

    Types of Wheel

    Configuration

    a) single trailer-truck unit

    b) tricycle landing gear with

    single tires

    c) twin-tandem landing gear

    d) double twin-tandem gear

  • Several Typical Aircrafts

  • Effect of Standard Deviation of Aircraft

    Wander on Pavement Damage

  • Measu

    red

    tra

    nsvers

    e

    cra

    ck f

    req

    uen

    cy (

    %)

    Pre

    dic

    ted

    tra

    nsvers

    e

    Eq

    uiv

    ale

    nt

    DC

    -8-6

    3F

    Str

    ain

    rep

    eti

    tio

    ns

    (taxiw

    ay)

    Np

    x 1

    03

  • Rigid Airport Pavement Design

    PCA method

    Corps of Engineering method

    FAA method: based on the Westergaard

    analysis of edge loaded slabs

  • FAA Pavement Design Principles

  • FAA Airport Pavement Design

  • Aircraft Considerations

    Load (95% main landing gear, 5% nose gear)

    Landing gear type and geometry

    Single gear aircraft

    Dual gear aircraft

    Dual tandem gear aircraft

    Wide body aircraft B-747, B-767, DC-10, L-1011

    Tire pressure: 75 to 200 psi (515 to 1,380 kPa)

    Traffic volume

  • AC 150/5320-6D

  • Equivalent Single Wheel Load (ESWL)

  • Design Procedure

    Forecast annual departures

    Select design aircraft that requires the thickest pavement

    Transform other aircrafts to equivalent departures of

    design aircraft

  • Determination of Design Aircraft

    The required pavement thickness for each aircraft type

    should be checked using the appropriate design curve

    and the forecast number of annual departures for that

    aircraft

    The design aircraft is the aircraft type that produces the

    greatest pavement thickness

    The design aircraft is not necessarily be the heaviest

    aircraft in the forecast

  • Factors for Converting Annual

    Departures by Aircraft to Equivalent

    Annual Departures by Design Aircraft

  • Conversion of Equivalent Annual

    Departure of Design Aircraft

    R1 equivalent annual departures of the design aircraft

    R2 annual departures expressed in design aircraft landing

    gear configuration

    W1 wheel load of the design aircraft

    W2 wheel load of the aircraft being converted

    Each wide body as a 300,000-pound dual tandem aircraft

    1

    221

    W

    WRlogRlog !

  • Example

    Aircraft

    727-100

    727-200

    707-320B

    DC-9-30

    CV-880

    737-200

    L-1011-100

    747-100

    Dual

    Dual

    Dual tandem

    Dual

    Dual tandem

    dual

    Dual tandem

    Double dual

    tandem

    160,000

    190,500

    327,000

    108,000

    184,500

    115,500

    450,000

    700,000

    Gear typeAvg. ann

    depart.

    Max. takeoff

    Weight (lbs).

    Equiv. dual

    gear depart

    3760

    9080

    5185

    5800

    680

    2650

    2907

    145

    Wheel load

    (lbs)

    Wheel load

    Design

    aircraft (lbs)

    Equiv. ann.

    depart. design

    aircraft

    38,000

    45,240

    38,830

    25,650

    21,910

    27,430

    35,625

    35,625

    45,240

    45,240

    45,240

    45,240

    45,240

    45,240

    45,240

    45,240

    1,891

    9,080

    2,764

    682

    94

    463

    1,184

    83

    3760

    9080

    3050

    5800

    400

    2650

    1710

    85

    727-200 requires the greatest pavement thickness and thus is the design aircraft

    1.7 x 85

    Conversion

    factor

    190,500x0.95/4

    45240

    35625)145log(Rlog 1 !

    300,000x0.95/8

    Wide body

    Total = 16,241

    Final design: 16,241 annual departures of a dual wheel aircraft weighing 190,500lbs

  • Typical Design Section of Runway

    Pavement

  • FAA Rigid Pavement Design

  • Principles of Rigid Airport Pavement

    Design

    Based on Westergaard analysis of edge loaded slabs

    (modified to simulate a jointed edge condition)

    Determine k value for rigid pavement

    Concrete flexural strength

    Gross weight of design aircraft

    Annual departures of design aircraft

  • Subbase Requirements

    A minimum thickness of 4 in. subbase

    Types of subbase courses

    - Item P-154: subbase course

    - Item P-208: aggregate base course

    - Item P-209: crushed aggregate base course

    - Item P-211: lime rock base course

    - Item P-304: cement treated base course

    - Item P-306: econocrete subbase course

    - Item P-401: plant mix bituminous pavements

    Stabilized subbase (aircraft weight > 100,000 lbs)

    - Item P-304: cement treated base course

    - Item P-306: econocrete subbase course

    - Item P-401: plant mix bituminous pavements

  • Exceptions for No Subbase

  • Concrete Flexural Strength

    Design strength of 600 to 650 psi is recommended for

    most airfield applications

    Strength at 28 days

    5% less than the test strength used for thickness design

  • Effect of Subbase on K- Well-Graded Crushed Aggregate

    (MN

    /m3)

    K o

    n t

    op

    of

    su

    bb

    as

    e(l

    b/i

    n3)

  • Effect of Subbase on K- Bank-Run Sand & Gravel (PI

  • Effect of

    Subbase

    on K- Stabilized

    Subbase

  • Design Curves Single Wheel Gear

    Gross weight of design aircraft

  • Design Curves Dual Wheel Gear

  • Design Curves Dual Tandem Gear

  • Critical and Noncritical Areas

    Total critical pavement thickness = T

    Noncritical pavement thickness (for concrete slab thickness)

    = 0.9T

    For variable section of the transition section and thinned

    edge, the reduction applies only to the concrete slab

    thickness

    The change in thickness for the transitions should be

    accomplished over an entire slab length and width

  • Critical and Non- critical Areas

    CriticalAircraft speed is low/ aircraft is at rest

    e.g. Apron, Taxiway

    Non-critical Aircraft speed is high/ aircraft is already partially airborne

    E.g. central portion of runway

  • Design Example

    Dual tandem aircraft: gross weight = 350,000 lbs, annual

    equivalent departures =6000 (including 1200 of B-747

    weighing 780,000 lbs)

    Subgrade k =100pci with poor drainage, frost penetration

    =18 in.

    Primary runway, 100% frost protection

    Subgrade soil is CL

    MR = 650 psi

    Stabilized

    subbase required

  • Design Steps

    Several thickness of subbase thickness should be tried =>

    most economical section

    Assume P-304 (cement treated base course) to be used

    Trial thickness of subbase = 6 in.

  • Slab Thickness

    16.6 in. round off to 17 in.

    17 + 6 =23 in. > 18 in. (frost depth)

    Wide body aircraft did not control slab thickness but to

    be considered in establishment of jointing requirements

    and design of drainage structures

  • Rigid Pavement Joint Types and Details

  • Recommended Maximum Joint Spacing- Rigid Pavement without Stabilized Subbase

  • Recommended Maximum Joint Spacing- Rigid Pavement with Stabilized Subbase

    Joint spacing (unit: in.)/radius of relative stiffness < 5.0

    to control transverse cracking

    Maximum joint spacing = 60 ft.

    Radius of relative stiffness:

    " #4/1

    2

    3

    k112

    Eh$%

    &'(

    )

    *+!

  • Dimensions and Spacing of Steel Dowels

  • Amount of Reinforcement for Reinforced

    Concrete Pavements

    s

    sf

    LtL7.3A !

    where As = area of steel per foot of width or length (in2)

    L = length or width of slab, ft.

    T = thickness of slab, in.

    fs = allowable tensile stress in steel, psi, 2/3 yield strength

    Minimum percentage of steel reinforcement = 0.05%

    to the area of concrete per unit length or width

  • Allowable Strengths of Various Grades of

    Reinforcing Steel

    Allowable

  • Dimensions and Unit Weights of

    Deformed Steel Reinforcing Bars

  • Sectional Areas of Welded Fabric

  • Jointing of Reinforced Rigid Pavements

  • Spreadsheet Programs

    F806FAA for flexible pavement design

    F805FAA for rigid pavement design

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