UFC 3-260-03
15 Apr 01
intersects the scale line representing the values of hE . The resulting value of hE represents the equiv-
alent thickness of the plain concrete pavement that would have the same load-carrying capacity as the
reinforced concrete pavement.
(2) In determining the equivalent thickness from figure 6-60, the effects of the reinforcing steel
on the load-carrying capacity will be disregarded when S is less than 0.05 and hE will simply equal hr.
Also, when S is greater than 0.5, the value of hE will be determined using the diagonal line representing
S = 0.5 percent.
(3) After the equivalent thickness has been determined, the method of evaluation will depend
on whether the reinforced concrete pavement is on grade, in any overlay system, or over a stabilized
layer. For reinforced concrete pavement on grade, the method of evaluation will be the same as for a
plain concrete pavement except that the hE value will be used instead of the reinforced concrete pave-
ment thickness hr . If the reinforced concrete pavement is part of an overlay system, the method of evalu-
ation to be used will depend on the type of overlay system. If the reinforced concrete pavement is placed
over a stabilized layer, it will be necessary to determine the equivalent thickness of plain concrete pave-
ment to account for the effect of the stabilized layer. First, the equivalent thickness due to the reinforcing
will be determined from figure 6-60. Second, using the above equivalent thickness, the effect of the
stabilized layer will be determined from equation 6-1. Using this thickness, hE , the evaluation will be
determined as for plain concrete pavement. In any case, the thickness to be used will be the appropriate
equivalent thickness, hE , rather than the thickness of the reinforced concrete pavement, hr.
c.
Evaluation Example for Reinforced Concrete Pavement. Assume:
(1)
Runway interior = type C traffic area.
(2)
Thickness of reinforced concrete pavement = 305 millimeters (12 inches).
(3)
Diameter of steel reinforcing bars, both longitudinal and transverse = 9.5 millimeters
(3/8 inch).
(4) Center-to-center spacing of reinforcing bars, both longitudinal and transverse = 152 milli-
meters (6 inches).
(5)
Flexural strength of concrete = 4.8 MPa (700 psi).
(6)
The k value for the foundation material = 27 kPa/mm (100 pci).
(7) The percentage of reinforcing steel in both the longitudinal and transverse directions is
computed by substituting in equation 6-2:
As
142
' 0.153 percent, using SI units
S'
100 '
Ap
93,025
As
0.221
100 ' 0.00153 100 ' 0.153 percent using IP units
S'
100 '
144
Ap
where
6-7
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