Given the following information for a continuously reinforced concrete pavement (CRCP), select a type of steel bars from the table below and determine the number of longitudinal steel bars for the 12-ft width of a concrete slab: the thickness of concrete slab D=9.5 in; the magnitude of wheel axle load due to traffic 20,000 lb; the resulting wheel load tensile stress ow=230 lbs/in (or psi); the effective modulus of subgrade reaction k = 170 lbs/in (or psi); the concrete indirect tensile strength ft = 550 lbs/in (or psi); the concrete shrinkage strain Z= 0.0004 in/in; the thermal coefficient of steel as = 5106 in/in/F; the thermal coefficient of concrete ac = 3.810-6 in/in/F; and the design temperature drop DTD= 55 F. The candidate steel bars types and the allowable steel stresses of them are shown in Table 12.6 below. Table 12.6 Allowable Steel Working Stress in Portland Concrete Reinforcement (Ref. 1 Used by Permission) Tensile Strength of Concrete at 28 Days (lbs/in) 800 Allowable Steel Stress (1000 lbs/in) Steel Bar No. 5 5/8-in diameter Steel Bar No. 4 1/2-in diameter 444666 65 67 67 67 67 67 = 57 60 61 63 65 67 Steel Bar No. 6 3/4-in diameter 54 55 56 58 59 60