Rigid Pavement Federal Aviation Design...Federal Aviation 22 Administration Rigid Pavement Design...

Federal AviationAdministration

Presented to: ACPA-SE Concrete Airport Pavement Workshop

By: Jeffrey S Gagnon, P.E.

Date: November 7, 2012

Rigid Pavement DesignPart ILarge Commercial Airport

2Federal AviationAdministration

Rigid Pavement Design – Part INovember 7, 2012

Starting Screen – No Job Files Created

Click on “New Job”



Creating/Naming a Job File

Enter Job Title

Click OK



Options Screen

Click Options



Options Screen



Copy Basic Section/Pavement Type from Samples

Click on “Samples”



7 Basic Starting Structures in FAARFIELDSection Name Pavement Type

ACAggregate New flexible on aggregate base

AConFlex HMA overlay on flexible pavement

AConRigid HMA overlay on rigid pavement

NewFlexible New flexible on stabilized base

New Rigid New rigid on stabilized base

PCConFlex PCC Overlay on flexible

PCConRigid Unbonded PCC on rigid

Be sure to select the pavement type that most correctly represents your design requirements.



Copy Basic Section/Pavement Type from Samples

Default Basic Pavement Sections

Click on “Copy Section”



Copy a Sample Pavement SectionClick on desired pavement section.

Then click on the project where the section will be saved.



Create a New Job Title

Enter job title

Click OK



Create a New Job Title

Click “End Copy”



Working With a Pavement Section

Select the job and then the section you want to analyze.

Click on “Structure” to open the file.



Working With a Pavement Section

The selected sample pavement will appear.

Click on “Modify Structure” to modify the structure if desired.



New Rigid Pavement Design Example # 1

• Pavement Structure:– PCC Slab, P-501, R = 700 psi– Cement-Treated Base, P-304, 6 in. thick– Crushed Aggregate Base, P-209, 8 in. thick– Subgrade k = 100 pci

• Traffic Mix:– 10-Aircraft Mix includes B777, A340, A380



Modifying a Pavement Section

Click on the box for the layer material type you want to modify.



Modifying a Pavement Section

Select the layer type you want to include in the pavement section.

(P-304 for this example)

Click OK



Modifying a Pavement Structure

Change P-209 layer thickness to 8 in.

Change subgrade k to 100 pci

Click “End Modify”



Layer Placement Restrictions• There are restrictions on placement of

certain pavement layers, e.g.:– Cannot place an overlay below a surface course.– Cannot have two aggregate base layers (P-209 on

P-209) in the structure.– Aggregate layer cannot be the surface layer.

• Some layer changes cause changes in the pavement type.– Changing the surface HMA layer to PCC will change

the pavement type to new rigid.



Enter Traffic Mixture

Click on “Airplane” to enter traffic mix




Use “Clear List” to clear the existing airplanes




For each airplane:

Click on the desired airplane group.

Then select the desired airplane from the library and click “Add”

Repeat for the complete traffic mixture.



Traffic Mix for This Example

No. NameGross Wt., lbs.

Annual Departures

Annual Growth, %

1 A320-100 150,796 600 0.002 A340-600 std 805,128 1,000 0.003 A340-600 std Belly 805,128 1,000 0.004 A380-800 1,239,000 300 0.005 B737-800 174,700 2,000 0.006 B747-400B Combi 877,001 400 0.007 B747-400 ER Pass. 913,000 300 0.008 B757-300 273,500 1,200 0.009 B767-400 ER 451,000 800 0.0010 B777-300 ER 777,000 1,000 0.0011 B787-8 (Preliminary) 486,000 600 0.00



Enter Traffic MixtureCertain airplanes may appear in the list twice. This is to address the presence of wing gears and belly gears.

FAARFIELD treats these as two airplanes.

However, the weight and departures are interlocked.



Adjusting Airplane InformationGross Taxi Weight, Annual Departures and % Annual Growth may be modified.



Adjusting Airplane Information- Gross Weight• There are limitations on changes to airplane gross

weights.• A range is provided for each airplane which

represents reasonable weights for the airplane:– Default Weight – 40%– Default Weight + 25%



Annual Departures in FAARFIELD

• Annual departures has the same meaning as in the previous design procedure.

• Arrivals are ignored.• For design purposes, FAARFIELD uses the

total annual departures, multiplied by the design period in years:– e.g., 1200 annual departures × 20 years = 24,000

departures.



Adjusting Airplane Information- % Annual Growth of Annual Departures

• Allowable range of percent annual growth is +/- 10%.

• You can create the same effect by modifying the annual departures.



Viewing Airplane Information

Scroll over to reveal additional columns of information.



Viewing Airplane InformationAvailable in FAARFIELD Airplane Screen:



Viewing Airplane Information

Values in CDF and P/C ratio columns will be zero when airplanes are first entered.

Save the list when finished entering, then click the Back button.



Run Design

Click on Design Structure



Run Design

During the design process, the “Design Running” clock will appear.

For rigid designs, the design will normally take a few minutes. Don’t interrupt the process.

The screen display will change with each iteration.



Final Design – Example 1



Reviewing Airplane Data After Completing the Design

Click on “Airplane”



Reviewing Airplane Data After Completing the Design

CDF and P/C ratio information is now available.

This information allows you to see which airplanes have the largest impact on the pavement design.



CDF Contribution

No. Name CDFContribution

CDF Maxfor Aircraft

P/CRatio

1 A320-100 0.00 0.00 3.842 A340-600 std 0.24 0.24 1.913 A340-600 std Belly 0.00 0.14 2.474 A380-800 0.01 0.01 3.615 B737-800 0.00 0.01 3.526 B747-400 Combi 0.02 0.02 3.467 B747-400 ER Passenger 0.04 0.04 3.628 B757-300 0.00 0.00 3.959 B767-400 ER 0.06 0.07 3.6510 B777-300 ER 0.59 0.59 3.8611 B787-8 (Preliminary) 0.04 0.05 3.78



Saving and Reviewing the Pavement Design Data

When finished with the design, click the “Back” button. Click “Yes” to save the data.



Reviewing Design Information

To view a summary of the design information, click the “Notes” button.



Reviewing Design Information

You can view the summary data or copy it to other electronic media.

Data can also be exported in XML format to allow automated entry into FAA Form 5100.



Rigid Design – Stabilized Base Material Sensitivity

P-306: PCC Surface - 18.27”P-304: PCC Surface – 18.38”P-401/403: PCC Surface – 18.40”

18.5”



• Flexural Strength (w/ P-304 Base & K=100 pci)

– 600 psi: 20.31”– 650 psi: 19.29– 700 psi: 18.38”– 750 psi: 17.49”

• Subgrade K Value (w/ P-304 Base & 700 psi Flex)

– 100 pci: 18.38”– 150 pci: 16.98”– 200 pci: 15.57”– 300 pci: 13.31”

FAARFIELD Rigid Design - Sensitivity



Flexural Strength RequirementsAC 150/5320-6E “Airport Pavement Design and Evaluation” p. 34-35 Section 327.a“Although the flexural strength required for the pavement design is related to the flexural strength required by the P-501 specification, the strengths used for the pavement design and the P-501 specification are not necessarily the same. Unless expedited construction requires early opening of the pavement to airplane traffic (e.g., less than 28 days), Item P-501 typically uses a 28-day strength as a practical construction measure. However, the long-term strength achieved by the concrete is normally expected to be at least 5 percent more than the strength measured at 28 days.

To establish the flexural strength for the thickness design the designer needs to consider several factors, such as: • Capability of the industry in a particular area to produce concrete at a particular strength• Flexural strength vs. cement content data from prior projects at the airport•T he need to avoid high cement contents, which can affect concrete durability• Whether early opening requirements necessitate using a lower strength than 28-day

The FAA recommends a design flexural strength of 600 to 700 psi (4.14 to 4.83 MPa) for most airfield applications. Lower strength requirements allow balancing the components of the concrete mixture for performance but may result in slightly thicker pavement requirements. However, these conditions reduce the risk of early cracking, minimize curling and warping stresses, and provide increased performance with respect to fatigue. The strength used for thickness design should be reduced by 5 percent when stating the P-501 specification requirements for the 28-day flexural strength.”



Flexural Strength RequirementsAC 150/5370-10F “Standards for Specifying Construction of Airports”“501-3.1 PROPORTIONS. Concrete shall be designed to achieve a 28-day flexural strength that meets or exceeds the acceptance criteria contained in paragraph 501-5.2 for a flexural strength of [ ] psi. The mix shall be designed using the procedures contained in Chapter 9 of the Portland Cement Association's manual, "Design and Control of Concrete Mixtures".

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

The Engineer shall designate the design strength. Refer to AC 150/5320-6 for guidance when specifying flexuralstrength. The minimum flexural strength allowable for airport pavements is 600 psi (4 136 kPa).

Higher flexural strength can be specified when local materials make this economically feasible. However, it must berecognized that due to variations in materials, operations, and testing, the average strength of concrete furnished by asupplier must be higher than the specified strength to insure a good statistical chance of meeting the acceptancecriteria throughout the duration of the job.

For pavements designed to accommodate aircraft gross weights of 30,000 pounds (13 500 kg) or less, this sectionmay be modified to indicate that concrete shall be designed to achieve a 28-day compressive strength such that meetsor exceeds the acceptance criteria for a compressive strength of 4,400 psi (30 700 kPa).

If the specified strength is required earlier than 28 days, the Engineer shall designate the time period.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *



Thank You

Questions?

Federal AviationAdministration

Presented to: ACPA-SE Concrete Airport Pavement Workshop

By: Jeffrey S Gagnon, P.E.

Date: November 7, 2012

Rigid Overlay DesignPart ILarge Commercial Airport



FAARFIELD Overlay Design

• HMA Overlays on Flexible Pavement– Same as designing a new flexible pavement, except the design

layer is the HMA overlay.

• PCC Overlays on Flexible Pavement– Same principle as new rigid design.

• HMA Overlays on Rigid Pavement• PCC Overlays on Rigid Pavement

– More complex than new rigid pavement design.– Both slabs (base PCC and overlay) deteriorate with applied

traffic. Stresses are computed for both slabs.– E-modulus of the base slab is a function of reduced SCI.– Subroutines were completely rewritten for FAARFIELD.



FAARFIELD Overlay Design –PCC on Rigid Overlays• Fully bonded overlays

– Treat as a new rigid pavement design.– Thickness of overlay slab is hoverlay = hdesign – hexist.

• Unbonded overlay– Bond breaker or leveling course is used.

• Partially bonded overlay– No longer a standard design in AC 150/5320-6E.– Default in FAARFIELD is off.– May be enabled from the Options window, but

displays a “Non Standard Structure” message.



FAARFIELD Overlay DesignRequired Inputs• Existing rigid pavement condition is characterized by the

Structural Condition Index (SCI). • SCI derived from PCI as determined by ASTM D 5340 Airport

Pavement Condition Index Surveys. The new AC gives guidance on SCI.

• SCI is computed using only structural components from the PCI survey.

• SCI = 80, FAA definition of structural failure (50% of slabs with structural crack)

• For existing pavements with structural damage (SCI < 100)– The user inputs a value of SCI for the existing pavement. The range of

allowable values depends on the overlay type: • Rigid on Rigid Overlays: SCI 40–100• Flexible on Rigid Overlays: SCI 67–100 (was 50-100)

– The Help file gives approximate formulas for relating SCI to Cr and Cb factors in earlier method.



Distress Severity LevelCorner Break Low, Medium, HighLongitudinal/Transverse/Diagonal Cracking Low, Medium, HighShattered Slab Low, Medium, HighShrinkage Cracks (cracking partial width of slab)* LowSpalling–Joint Low, Medium, HighSpalling–Corner Low, Medium, High

FAARFIELD – PCC Unbonded Overlay Design Structural Condition Index (SCI)

Rigid Pavement Distress Types Used to Calculate SCI

* Used only to describe a load-induced crack that extends only part of the way across a slab. The SCI does not include conventional shrinkage cracks due to curing or other non load-related problems.



Cumulative Damage Factor Used (CDFU)

• For existing pavements where SCI=100 (no structural distress):– There is no visible distress contributing to reduction

in SCI (no structural distress types). However, some pavement life has been consumed by the applied traffic.

– The amount of pavement life consumed is the percent CDF Used (%CDFU).

– Need to estimate a value of %CDFU. – The Help file gives guidance on estimating %CDFU

using the Life key.



– CDFU defines the amount of structural life used. • For structures with aggregate base:

• LU = number of years of operation of the existing pavement until overlay• LD = design life of the existing pavement in years

– FAARFIELD modifies this relationship for stabilized subbases to reflect improved performance.

Cumulative Damage Factor Used (CDFU)



Rigid on Rigid Overlay SCI Example• Pavement Structure:

– Rigid Overlay (P-501)– PCC Slab (P-501), 17.5 in.,

R = 700 psi, SCI = 70– Cement Treated Base (P-304), 6 in.– Crushed Aggregate Base (P-209), 8 in.– Subgrade k = 100 pci

• Traffic Mix:– Add A380-800 and B-747-8 Freighter to Aircraft list



Rigid Overlay Design

Click “Back”



Rigid Overlay Design - Copy Basic Section

Click on “Samples”



Rigid Overlay Design - Copy Basic Section

Default Basic Pavement Sections

Click on “Copy Section”



7 Basic Starting Structures in FAARFIELDSection Name Pavement Type

ACAggregate New flexible on aggregate base

AConFlex HMA overlay on flexible pavement

AConRigid HMA overlay on rigid pavement

NewFlexible New flexible on stabilized base

New Rigid New rigid on stabilized base

PCConFlex PCC Overlay on flexible

PCConRigid Unbonded PCC on rigid

Be sure to select the pavement type that most correctly represents your design requirements.



Rigid Overlay Design / Copy a Sample Pavement Section

Click on desired pavement section.

Then click on the project where the section will be saved.



Rigid Overlay Design / Create a New Job Title

Enter job title

Click OK



Rigid Overlay Design / Create a New Job Title

Click “End Copy”



Rigid Overlay Design / Working With a Pavement Section

Select the job and then the section you want to analyze.

Click on “Structure” to open the file.




Standard Cross Section

Click on “Modify Structure”.




Modify the Cross Section

Click on “Airplane”.



Rigid Overlay Design - Add Airplane

For each airplane:

Click on the desired airplane group.

Then select the desired airplane from the library and click “Add”

Click “Save”



Performing Overlay Design

The layer with the small arrow is the layer that will be adjusted to provide the structural design.

The location of the arrow is determined by the type of structure.



Performing Overlay Design

You are now ready to design the structure. Simply click on “Design Structure.”

The program will keep you informed about the status of the design.



Result of Overlay Design

10.5”P-501 PCC Overlay



Rigid on Rigid Overlay % CDFU Example• Pavement Structure:

– Rigid Overlay (P-401)– PCC Slab (P-501), 16.0 in.,

R = 700 psi, SCI = 100– Cement Treated Base (P-304), 6 in.– Crushed Aggregate Base (P-209), 8 in.– Subgrade k = 100 pci

• Traffic Mix:– Original B737-800, B737- 900 and A310-300– Add B-747-400ER, B767-300ER and B777 (all Freighter

Models)



Calculation of %CDFUChange Design life from 20 to 8

Click Life



% CDFU Calculated

%CDFU= 50%



Make Sure to modify all relevant data



You are now ready to design the structure. Simply click on “Design Structure.”



Result of Overlay Design

7.5”P-501 PCC Overlay



Software Available at:

• http://www.faa.gov/airports/engineering/design_software/

• http://www.airporttech.tc.faa.gov/naptf/download/index1.asp



Thank You

Questions?

Rigid Pavement Federal Aviation Design...Federal Aviation 22 Administration Rigid Pavement Design...

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