150_5320_6d_part4

150_5320_6d_part4 - AC 150/5320-6D 7f7l95 U! SS3NXlIHL EWIS...

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AC 150/5320-6D 7f7l95 U! ‘SS3NXlIHL EWIS 82
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L-1011-100, 200 CONTACT AREA = 337 SQ. IN. DUAL SPACING = 52 IN. TANDEM SPACING = 70 IN. nnn 650 600 mn ANNUAL DEPARTURES 1,200 6,000 25,000 3,000 15,000 -10 -17 -16 -15 -14 -13 -12 -11 -iii -9 -8 -7 19 18 17 16 15 14 13 12 11 10 9 0 7 -20 -21 -19 -20 -10 -19 -17 -18 -16 ---I7 -15 -16 -14 -15 -13 l4 12 8 -0 i 23 22 21 20 16 15 14 t 13 1 11 10 L- 9 0 NOTE: 1 inch = 25.4 mm 1 psi = 1 lb = 0.454 kg 1 pci = FIGURE. 3-41. OPTIONAL PAVEMENT DESIGN CURVES, L-1011-100,200
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AC 150/5320-60 7m95 334. DESIGN EXAMPLE. As an example of the use of the design curves, assume that a rigid pavement is to be designed for dual tandem aircraft having a gross weight of 350,000 pounds (160 000 kg) and for 6,000 annual equivalent departures of the design aircraft. The equivalent annual departures of 6,000 include 1,200 annual departures of B-747 aircraft weighing 780,000 pounds (350 000 kg) gross weight. The subgrade modulus of 100 PC1 (25 MN/m3) with poor drainage and frost penetration is 18 inches (460 mm). The feature to be designed is a primary runway and requires 100 percent frost protection. The subgrade soil is CL. Concrete mix designs indicate a flexural strength of 650 PSI (4.5 MN/m*) can be readily produced with locally available aggregates. The gross weight of the design aircraft dictates the use of a stabilized subbase. Several thicknesses of stabilized subbases should be tried to determine the most economical section. Assume a stabilized subbase of P-304 will be used. Try a subbase thickness of 6 inches (150 mm). Using Figure 3-16, a 6-inch (150 mm) thickness of P-304 would likely increase the foundation modulus from 100 PC1 (25 MN/m’) to 210 PC1 (57 MN/m3). Using Figure 3-19, dual tandem design curve, with the assumed design data, yields a concrete pavement thickness of 16.6 inches (422 mm). This thickness would be rounded off to 17 inches (430 mm). Since the frost penetration is only 18 inches (460 mm) and the combined thickness of concrete pavement and stabilized subbase is 23 inches (585 mm), no further frost protection is needed. Even though the wide body aircraft did not control the thickness of the slab, the wide bodies would have to be considered in the establishment of jointing requirements and design of drainage structures. Other stabilized subbase thicknesses should be tried to determine the most economical section. .- 335. FROST EFFECTS. As with flexible pavements, frost protection should be provided for rigid pavements in areas where conditions conducive to detrimental frost action exist. Frost protection considerations for rigid pavements are similar to those for flexible pavements. The determination of the depth of frost protection required is given in paragraph 308.b. Local experience may be used to refine the calculations. a. Example. Assume the above design example is for a primary runway and requires complete frost protection. The subgrade soil is CL, weighing 115 lb&u ft (184 kg/cu m). The design freezing index is 500 degree days. Referring to Figure 2-6 shows the depth of frost penetration to be 34 inches (865 mm). The structural considerations yield a 23 inch (585 mm) thickness of non-frost susceptible material. Since the frost penetration is only
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This note was uploaded on 01/07/2012 for the course CEE 4674 taught by Professor Staff during the Fall '11 term at Virginia Tech.

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150_5320_6d_part4 - AC 150/5320-6D 7f7l95 U! SS3NXlIHL EWIS...

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