322
Table 8.3 Material Properties and Results of Stress
Analysis for US 441 (Columbia County)
a) Input Parameters for BISAR
Layer
Description
Thickness
Poisson's
Modulus
(psi)
(in.)
Ratio
Dynaflect
FWD
1
Asphalt Concrete
3.0
0.35
1,453,200 *
1,453,200 *
2
Limerock Base
9.0
0.35
85,000
55,000
3
Subbase
12.0
0.35
60,000
35,000
4
Subgrade
semi-
infinite
0.40
27,500
20,000
* Computed at 23F using log = 6.4167 0.01106T for pavements at
incipient failure.
b) Pavement Stress Analysis
Response Parameters**
Dynaflect
FWD
Maximum Surface Deflection
(mils)
10.0
12.4
Radial stress, bottom of AC layer
(psi)
208.0
267.0
Radial strain, bottom of AC layer
(E-6
in./in.)
93.9
115.0
Vertical stress, top of base layer
(psi)
-42.0
35.0
Radial stress, top of base layer
(psi)
-8.0
-7.1
Vertical stress, top of subbase layer
(psi)
-12.1
-11.4
Radial stress, top of subbase layer
(psi)
0.02
-0.5
Vertical stress, top of subgrade
(psi)
-4.2
-4.8
Vertical strain, top of subgrade
(E-6
in./in.)
-155.0
-176.0
Deflection in AC layer
(%)
1.0
0.8
Deflection in base layer
(%)
23.8
25.8
Deflection in subbase layer
(%)
17.0
21.6
Deflection in subgrade layer
(%)
58.2
51.8
* Computed for single axle with dual wheels (6.0 kips/wheel)
NOTE: + = tensile
- = compressive