lecture 21 faa rigid
DESCRIPTION
Rigid pavment design by FAATRANSCRIPT
PAVEMENT DESIGN
AND ANALYSIS
(CE-860)
LEC-21
Fall Semester 2015
Dr. Arshad Hussain
[email protected] , Office Room#111, Tel: 05190854163, Cell: 03419756251
National Institute of Transportation (NIT)
School of Civil & Environmental Engineering (SCEE)
National University of Science and Technology (NUST)
NUST Campus, Sector H-12, Islamabad
RIGID AIRPORT PAVEMENT DESIGN
FAA DESIGN METHOD
FAA DESIGN PROCEDURE
1. Design Inputs
a. Concrete flexural strength (90 days)
b. Modulus of subgrade reaction (k)
c. Gross weight of design aircraft
d. Equivalent annual departure of design
aircraft
FAA DESIGN PROCEDURE
2. Thickness Selection
a. Separate design curves for single, dual and
dual tandem gear assembly and separate
wide body aircraft.
b. Design curves indicate thickness of PCC
slab only and this thickness ‘ T ’ is the
critical thickness.
FAA DESIGN PROCEDURE
3. Subbase Requirements
a. A minimum thickness of 4 inches of
subbase required except as shown in
Table 3-10 conditions where no subbase
is required.
Soil
Classifi
cation
Good Drainage Poor Drainage
No
FrostFrost
No
FrostFrost
GW x x x x
GP x x x
GM x
GC x
SW x
x indicates conditions where no subbase is required
TABLE 3-10
FAA DESIGN PROCEDURE
b. Subbase thickness in excess of 4 inches
can be used to decrease the required
thickness, if economical.
c. Stabilized subbase is required if aircraft
weighing more than 100,000 lbs is
present in the mix.
Conversions for different gear types
FAA DESIGN PROCEDURE
4. Subgrade Compaction Requirement
a. For Cohesive Soils
Must be compacted to 90 % maximum
density for fill (ASTM D 698)
Top 6 inches must be compacted to 90%
maximum density in cut section.
FAA DESIGN PROCEDURE
b. For Cohesionless Soils
In fill section top 6 inches must be compacted
to 100 % maximum dry density and remainder
95 %.
In cut section Top 6 inches must be compacted
to 100% maximum density and next 18 inches
to 95 %.
FAA DESIGN PROCEDURE
5. Determination of k
a. k should be assigned to material directly
beneath concrete slab.
b. Determine k for subgrade soil and use curve
to improve k values for given subbase material
& thickness Table 2-3
c. Use Fig. 2-4 to improve k for untreated
subbase.
Effect of subbase on k (well graded crushed aggregate)
Effect of subbase on k (bank-run sand & gravel)
FAA DESIGN PROCEDURE
Use Fig. 3-16 to improve k for stabilized
subbase (applicable to cement or
bituminous treated subbase.
FAA DESIGN PROCEDURE
6. Critical & non-critical areas
Fig. 3-1
a. Design curves give T, the critical thickness
b. 0.9T thickness for non-critical areas
applicable to concrete slab.
c. Variable thickness section & thinned edge
section reduction factors (0.7 T) applies to
slab thickness.
FAA DESIGN PROCEDURE
d. Subbase thickness must be adjusted to
provide continuous drainage at subgrade.
High TrafficVolume
Provide additional thickness for
departures in excess of 25,000 according
to Table 3-5.
Pavement Thickness for Higher
Departure Levels
For annual departures in excess of 25,000 the total
pavement thickness should be increased as shown below:
________________________________________
Annual departure Per cent of 25000
level departure thickness
________________________________________
50,000 104
100,000 108
150,000 110
200,000 112
________________________________________
DESIGN EXAMPLE
DESIGN EXAMPLE (Cont)
Assumed Material Properties
FAA Software for Rigid
R805FAA For Rigid Pavement Design