UFC 3-260-02

30 June 2001

5.

REINFORCING STEEL DESIGN.

a. Longitudinal Direction. The percent of reinforcing steel required in the longitudinal direction for

continuously reinforced concrete pavements will be the maximum calculated by the following three

equations with the minimum percent steel being 0.43 percent.

&

(15-1)

(15-2)

&) ,

(15-3)

where

Ps = percent of reinforcing steel required in the longitudinal direction

F = friction factor; suggested values are 1.0 for unbound fine-grained soils, 1.5 for unbound

coarse-grained soils, and 1.8 for stabilized soils

ft = 7-day tensile strength of the concrete in MPa (psi) determined using the splitting tensile test

(Figure 5-1 may be used to convert 7-day flexural strength into tensile strength.)

fs = working stress in the steel, MPa (psi) (75 percent of yield tensile strength of steel). This

produces a safety factor of 1.33.

)T = seasonal temperature differential in degrees Celsius (Fahrenheit)

,c = thermal coefficient of expansion of concrete in millimeters per millimeter per degree Celsius

(inches per inch per degree Fahrenheit)

b. Transverse Direction. Transverse reinforcement is required for all continuously reinforced

concrete airfield pavements to control any longitudinal cracking that may develop from load repetitions.

The percent steel required in the transverse direction will be determined as follows:

(15-4)

where

Ws = width of slab, m (ft)

15-2

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