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:

142

' 0.153 *percent*, *using SI units*

100 '

93,025

0.221

100 ' 0.00153 100 ' 0.153 *percent using IP units*

100 '

144

where

6-7