6P-MunicipalPavementDesignwithStreetPaveSoftware-Haisl

8/13/2019 6P-MunicipalPavementDesignwithStreetPaveSoftware-Haisl

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March 5, 2009

Scott HaislipSenior VP Pavement Engineering

Municipal Pavement Designwith StreetPave Software


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Presentation Overview

Background / history of the design procedure Concrete pavement design principles Discussion of the primary factors (inputs)

affecting concrete pavement design Example using StreetPave design software


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Thickness Design Basics

Municipal Pavement Design


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Streets and Local Roads Thickness Design Procedure

Longitudinal joint

Transverse joint

Subgrade

Subbase or base

Surface Texture

Surface smoothnessor r ideability

Thickness Design

Dowel bars

Concrete materials

Tiebars


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Thickness Design Procedures

Empirical Design Based on observed performance

AASHO Road Test

Mechanistic Design Based calculated pavement

responses PCA Design Procedure

(PCAPAV)

StreetPave (ACPA DesignMethod)

AASHO Test Road:Ottawa, Illinois (approximately 80 miles southwest ofChicago) between 1956 and 1960


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StreetPave Design Software

Pavement design toolgeared primarily forroads & streets

Based on the PCAs pavement thicknessdesign methodology

Checks adequacy ofconcrete thicknessusing both fatigue anderosion criteria


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Concrete Pavement Types

Jointed Plain Undoweled Doweled

Jointed Reinforced Continuously

Reinforced Prestressed


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Jointed Plain


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SLR Pavement Design Street classification

Traffic Geometric design Subgrade and subbase Concrete quality Thickness design

Jointing Dowel Bar Recommendations


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Geometric DesignMunicipal Pavement Design


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Edge SupportConcrete Shoulder Curb & Gutter Widened Lane

or

s e p a r a

t e

i n t e g r a

l


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Basic Two-Lane Sections

No curb

Integral curb

25 to 28 wide

Separate curb

25-2818 min.

L

PLAN

PROFILE

No curb

Integral curb

28 to 42 wide

Separate curb

28-42

18 min.1/3 width(typ.)

L

PLAN

PROFILE

NOT TO SCALE


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Subgrades and Subbases

Municipal Pavement Design

Subgrade Natural ground, graded, and compacted on which

the pavement is built.

Subbase

Layer of material directly below the concrete pavement.


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Design for Uniform SupportThree Major Causes for Non-Uniform Support

Expansive Soils

Differential Frost Heave

Pumping (loss of support)


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Subgrade Properties

Modulus ofSubgrade Reaction,k-value

Plate load on subgradePlate deflection on subgradek =

5.0 psi

0.5 ink = = 100 psi / in.

Reaction

Stacked PlatesPressure Gage

Subgrade

Plate-Load Test


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Type of Soil Support k value range)

Fine-grained soils inwhich silt and clay-size particlespredominate

Low 75 - 120 pci(20 - 34 MPa/m)

Sands and sand-gravel mixtures withmoderate amounts

of silt and clay

Medium 130 - 170 pci(35 - 49 MPa/m)

Sands and sand-gravel mixtures

relatively free ofplastic fines

High 180 - 220 pci

(50 - 60 MPa/m)

Subgrade Soil Types and Approximate k ValuesSubgrade Properties


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Subgrade Properties

Soil Type SupportResil ient Modulus

(MR), psi

Fine-grained withhigh amounts ofsilt/clay

Low 1455-2325

Sand and sand-gravel with

moderate silt/clay

Medium 2500-3300

Sand and sand-gravel with little or

no silt/clay

High 3500-4275

Resilient Modulus of the Subgrade


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Subgrade Properties

Subgradek-value

(pci)

Thickness of Unbound Granular orCrushed Stone Subbase4 6 9 12

50 65 75 85 110

100 130 140 160 190

150 176 185 215 255

200 220 230 270 320

Typical composite k-values for unbound granular, aggregate, orcrushed stone subbase


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Subgrade and Subbases DesignSummary

Subgrade strength is not a critical element in thethickness design . Has little impact on thickness.

Need to know if pavement is on: Subgrade (k 100 psi/in. (25 MPa/m)),

Granular subbase (k 150 psi/in. (40 MPa/m)),

Asphalt treated subbase (k 300 psi/in. (80 MPa/m))

Cement treated/lean concrete subbase (k 500 psi/in.(125 MPa/m)).


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Subbase EffectsAt the AASHO Road Test,

concrete pavements withgranular bases could carryabout 30% more traffic.

The current design proceduresallows concrete pavements

built with granular bases to

carry about 5 - 8% moretraffic.


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Fatigue Analysis

Allowable number of

load repetitions foreach axle group isdetermined

% Fatigue iscalculated for eachaxle group

Total fatigueconsumed should notexceed 100%.

Midslab loading away fromtransverse joint producescritical edge stresses

Fatigue

Critical Loading Position

Transverse joint


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Pavement Design Principle #1Stress / Fatigue

Compressive strength: ~4000 psi Flexural strength: ~600 psi

T

C


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Pavement Design Principle #1Stress / Fatigue


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Thickness Design ProcedureConcrete Properties

Flexural Strength(Modulus of Rupture, ASTM C78)

Avg. 28-day strength in

3rd-point loading Other Factors:

Concrete Strength Gain

w/ Age Fatigue Properties L/3

Span Length = L

d=L/ 6

Third-point Loading


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Concrete Strength PropertiesIf specify minimum flexural

strength at 28-day of 550psi & allow 10% of beams tofall below minimum:

STEP 1Estimate SDEV:

9% for typical ready mix.SDEV = 550 * 0.09 = 50 psi

STEP 2

Sc design = Sc minimum + z *SDEVSc design = 550 + 1.282 * 50Sc design = 614 psi

40

60

80

100

120

140

160

3d 7d 3m 3y 20y Age

P e r c e n

t a g e o

f 2 8 - d a y

S t r e n g

t h

Type I (GU)Type III (HE)

28d 1y 5y 10y

40

60

80

100

120

140

160

3d 7d 3m 3y 20y Age

P e r c e n

t a g e o

f 2 8 - d a y

S t r e n g

t h

Type I (GU)Type III (HE)

28d 1y 5y 10y


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Design Period/Life 20 to 35 years is commonly used Shorter or longer design period may be

economically justified in some cases

High performance concrete pavements Long-life pavements A special haul road to be used for only a few years

Cross-overs Temporary lanes


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Reliability Is simply the factor of safety Usually expressed as % Is a measure of how likely the

design will fail due to fatigueor erosion

Or can be used to estimate theamount of pavement repairrequired at the end of design

period/lifeProbability of Winning


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Reliability

Functional Classificationof Roadway

Recommended Reliability

Urban Rural

Interstates, Freeways, andTollways 85 - 99 80 99

Principal Arterials 80 - 99 75 95

Collectors 80 - 95 75 95

Residential & Local Roads 50 - 80 50 80

Levels of Reliability for Pavement Design


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Thickness Design

Roadway Type

Recommended

Percent of SlabsCracked at End ofDesign Life

(Default) 15%

Interstate Highways,Expressways, Tollways,Turnpikes

5%

State Roads, Arterials 10%

Collectors, County Roads 15%

Residential Streets 25%

Recommended Levels of Slab Cracking by Roadway Type


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Effects of Combined Reliability &Slab Cracking


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Pavement Design Principle #2

Deflection / Erosion / PumpingFaulting


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Design - ErosionConditions for Pumping:

Subgrade soil that will gointo Suspension Free water between slab

and subgrade Frequent heavy wheel

loads / large deflections


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Concrete Pavement Design for Municipal Streets

Load Transfer = slabs ability to share its load with neighboring

slabs Aggregate Interlock Dowels Edge Support

Tied curb & gutter Integral curb & gutter Parking lane

Tied concrete

L= x

U= 0

Poor Load Transfer

Good Load Transfer

L= x/2 U = x/2


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Aggregate Interlock

Shear between aggregate particles

below the initial saw cut


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Dowel Recommendations Dowels

recommendations: If pavement thickness is 7

or less dowels notrecommended

If pavement thickness is 7.0& 7.5 use 1 dowels,stabilized subgrade, or 4-6subbase. Note: If erosion isthe failure mechanism.

If pavement thickness is 8or greater use 1 dowels


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Dowel bars Length 14 min.

6.0 in. minimumembedment length Diameter:

1.0 in streets and roads 1.25 - 1.50 in. for arterials roads

Epoxy or other corrosion

protection for harshclimates


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Jointing

Control naturaltransverse and

longitudinal crack frominternal slab stresses Divide pavement into

construction lanes or

increments Accommodate slab

movements Provide load transfer Provide uniform sealant

reservoir

Longitudinal JointsDivides pavement lanes (8-12 ft.)Depth - 1/3 pavement thickness

Transverse JointsTransverse Contraction Joints (8-15 ft.Depth - 1/3 pavement thickness


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StreetPave User Inputs & Outputs Global Settings

Region Units (English or Metric) Terminal Serviceability Percent Slabs Cracked

at end of design Life Design Life Reliability

Traffic Pavement Properties Thickness/Dowel/Jointing Recommendations


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Design Example Inputs Design life = 30 years

k-value = 100 pci Concrete flexural strength = 600 psi Load transfer (dowels) = No/yes

Edge support = yes Traffic category = Collector 2-way ADTT = 100

Reliability = 80% Percent Slabs Cracked = 15%


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Design and Analysis Summary Replace


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with PDF Desktop

Sensitivity Charts


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y


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Summary StreetPave program incorporates reliability and

slab cracking into fatigue for concrete pavement design Can be used to compare the outcome of

altering design inputs to obtain cost-effective pavement sections

Principles can also be applied to concreteoverlays


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StreetPave Software Availability

Available from:

Bob LongExecutive Director Mid-Atlantic Chapter ACPA

Patch v1.3: www.pavement.com

Questions?


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Thank You!!!

Please contact PRESENTER

with questions or comments:[email protected]

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