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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
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Rigid Pavement Design – Part INovember 7, 2012
Starting Screen – No Job Files Created
Click on “New Job”
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Rigid Pavement Design – Part INovember 7, 2012
Creating/Naming a Job File
Enter Job Title
Click OK
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Rigid Pavement Design – Part INovember 7, 2012
Options Screen
Click Options
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Rigid Pavement Design – Part INovember 7, 2012
Options Screen
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Rigid Pavement Design – Part INovember 7, 2012
Copy Basic Section/Pavement Type from Samples
Click on “Samples”
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Copy Basic Section/Pavement Type from Samples
Default Basic Pavement Sections
Click on “Copy Section”
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Rigid Pavement Design – Part INovember 7, 2012
Copy a Sample Pavement SectionClick on desired pavement section.
Then click on the project where the section will be saved.
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Rigid Pavement Design – Part INovember 7, 2012
Create a New Job Title
Enter job title
Click OK
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Rigid Pavement Design – Part INovember 7, 2012
Create a New Job Title
Click “End Copy”
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Rigid Pavement Design – Part INovember 7, 2012
Working With a Pavement Section
Select the job and then the section you want to analyze.
Click on “Structure” to open the file.
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Rigid Pavement Design – Part INovember 7, 2012
Working With a Pavement Section
The selected sample pavement will appear.
Click on “Modify Structure” to modify the structure if desired.
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Rigid Pavement Design – Part INovember 7, 2012
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
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Rigid Pavement Design – Part INovember 7, 2012
Modifying a Pavement Section
Click on the box for the layer material type you want to modify.
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Rigid Pavement Design – Part INovember 7, 2012
Modifying a Pavement Section
Select the layer type you want to include in the pavement section.
(P-304 for this example)
Click OK
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Rigid Pavement Design – Part INovember 7, 2012
Modifying a Pavement Structure
Change P-209 layer thickness to 8 in.
Change subgrade k to 100 pci
Click “End Modify”
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Enter Traffic Mixture
Click on “Airplane” to enter traffic mix
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Rigid Pavement Design – Part INovember 7, 2012
Enter Traffic Mixture
Use “Clear List” to clear the existing airplanes
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Rigid Pavement Design – Part INovember 7, 2012
Enter Traffic Mixture
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.
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Rigid Pavement Design – Part INovember 7, 2012
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
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Adjusting Airplane InformationGross Taxi Weight, Annual Departures and % Annual Growth may be modified.
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Rigid Pavement Design – Part INovember 7, 2012
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%
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Viewing Airplane Information
Scroll over to reveal additional columns of information.
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Rigid Pavement Design – Part INovember 7, 2012
Viewing Airplane InformationAvailable in FAARFIELD Airplane Screen:
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Run Design
Click on Design Structure
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Final Design – Example 1
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Rigid Pavement Design – Part INovember 7, 2012
Reviewing Airplane Data After Completing the Design
Click on “Airplane”
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
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
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Rigid Pavement Design – Part INovember 7, 2012
Saving and Reviewing the Pavement Design Data
When finished with the design, click the “Back” button. Click “Yes” to save the data.
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Rigid Pavement Design – Part INovember 7, 2012
Reviewing Design Information
To view a summary of the design information, click the “Notes” button.
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
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Rigid Pavement Design – Part INovember 7, 2012
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”
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Rigid Pavement Design – Part INovember 7, 2012
• 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
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Rigid Pavement Design – Part INovember 7, 2012
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.”
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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.
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
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Rigid Pavement Design – Part INovember 7, 2012
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
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
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.
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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.
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Rigid Pavement Design – Part INovember 7, 2012
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.
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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.
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– 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)
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Rigid Pavement Design – Part INovember 7, 2012
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
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design
Click “Back”
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design - Copy Basic Section
Click on “Samples”
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design - Copy Basic Section
Default Basic Pavement Sections
Click on “Copy Section”
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design / Copy a Sample Pavement Section
Click on desired pavement section.
Then click on the project where the section will be saved.
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design / Create a New Job Title
Enter job title
Click OK
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design / Create a New Job Title
Click “End Copy”
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design
Standard Cross Section
Click on “Modify Structure”.
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Rigid Pavement Design – Part INovember 7, 2012
Rigid Overlay Design
Modify the Cross Section
Click on “Airplane”.
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Rigid Pavement Design – Part INovember 7, 2012
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”
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
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.
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Rigid Pavement Design – Part INovember 7, 2012
Result of Overlay Design
10.5”P-501 PCC Overlay
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Rigid Pavement Design – Part INovember 7, 2012
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)
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Calculation of %CDFUChange Design life from 20 to 8
Click Life
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% CDFU Calculated
%CDFU= 50%
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Make Sure to modify all relevant data
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You are now ready to design the structure. Simply click on “Design Structure.”
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Result of Overlay Design
7.5”P-501 PCC Overlay
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Software Available at:
• http://www.faa.gov/airports/engineering/design_software/
• http://www.airporttech.tc.faa.gov/naptf/download/index1.asp
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Rigid Pavement Design – Part INovember 7, 2012
Thank You
Questions?
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