30 June 2001
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.
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)
Es = modulus of elasticity of the reinforcing steel in tension, MPa (psi)
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:
Ws = width of slab, m (ft)