AIRPORT PLANNING MANUAL RADIUS OF RELATIVE STIFFNESS ( ) VALUES IN INCHES = 4 Ed3 =24.1652 4 d3 2 12( 1− )k k 6 WHERE: E = YOUNG’S MODULUS = 4 x 10 psi 3 k = SUBGRADE MODULUS, lb/in. d = RIGID−PAVEMENT THICKNESS. in. = POISSON’S RATIO = 0.15 d(in) k=75 k=100 k=150 k=200 k=250 k=300 k=350 k=400 k=500 k=550 6.0 31.48 29.30 26.47 24.63 23.30 22.26 21.42 20.72 19.59 19.13 6.5 33.43 31.11 28.11 26.16 24.74 23.64 22.74 22.00 20.80 20.31 7.0 35.34 32.89 29.72 27.65 26.15 24.99 24.04 23.25 21.99 21.47 7.5 37.22 34.63 31.29 29.12 27.54 26.32 25.32 24.49 23.16 22.61 8.0 39.06 36.35 32.85 30.57 28.91 27.62 26.58 25.70 24.31 23.74 8.5 40.88 38.04 34.37 31.99 30.25 28.91 27.81 26.90 25.44 24.84 9.0 42.67 39.71 35.88 33.39 31.58 30.17 29.03 28.08 26.55 25.93 9.5 44.43 41.35 37.36 34.77 32.89 31.42 30.23 29.24 27.65 27.00 10.0 46.18 42.97 38.83 36.14 34.17 32.65 31.42 30.39 28.74 28.06 10.5 47.90 44.57 40.28 37.48 35.45 33.87 32.59 31.52 29.81 29.11 11.0 49.60 46.16 41.71 38.81 36.71 35.07 33.75 32.64 30.87 30.14 11.5 51.28 47.72 43.12 40.13 37.95 36.26 34.89 33.74 31.91 31.16 12.0 52.94 49.27 44.52 41.43 39.18 37.44 36.02 34.84 32.95 32.17 12.5 54.59 50.80 45.90 42.72 40.40 38.60 37.14 35.92 33.97 33.17 13.0 56.22 52.32 47.27 43.99 41.61 39.75 38.25 36.99 34.99 34.16 13.5 57.83 53.82 48.63 45.26 42.80 40.89 39.35 38.06 35.99 35.14 14.0 59.43 55.31 49.98 46.51 43.98 42.02 40.44 39.11 36.99 36.12 14.5 61.02 56.78 51.31 47.75 45.16 43.15 41.51 40.15 37.97 37.08 15.0 62.59 58.25 52.63 48.98 46.32 44.26 42.58 41.19 38.95 38.03 15.5 64.15 59.70 53.94 50.20 47.47 45.36 43.64 42.21 39.92 38.98 16.0 65.69 61.13 55.24 51.41 48.62 46.45 44.70 43.23 40.88 39.92 16.5 67.23 62.56 56.53 52.61 49.75 47.54 45.74 44.24 41.84 40.85 17.0 68.75 63.98 57.81 53.80 50.88 48.61 46.77 45.24 42.78 41.78 17.5 70.26 65.38 59.08 54.98 52.00 49.68 47.80 46.23 43.72 42.70 18.0 71.76 66.78 60.34 56.15 53.11 50.74 48.82 47.22 44.66 43.61 18.5 73.25 68.17 61.60 57.32 54.21 51.80 49.84 48.20 45.59 44.51 19.0 74.73 69.54 62.84 58.48 55.31 52.84 50.84 49.17 46.51 45.41 19.5 76.20 70.91 64.08 59.63 56.39 53.88 51.84 50.14 47.42 46.30 20.0 77.66 72.27 65.30 60.77 57.47 54.91 52.84 51.10 48.33 47.19 20.5 79.11 73.62 66.52 61.91 58.55 55.94 53.83 52.06 49.23 48.07 21.0 80.55 74.96 67.74 63.04 59.62 56.96 54.81 53.01 50.13 48.95 21.5 81.99 76.30 68.94 64.16 60.68 57.97 55.78 53.95 51.02 49.82 22.0 83.41 77.63 70.14 65.28 61.73 58.98 56.75 54.89 51.91 50.69 22.5 84.83 78.95 71.34 66.38 62.78 59.99 57.72 55.82 52.79 51.55 23.0 86.24 80.26 72.52 67.49 63.83 60.98 58.68 56.75 53.67 52.41 23.5 87.64 81.56 73.70 68.59 64.86 61.97 59.63 57.67 54.54 53.26 24.0 89.04 82.86 74.87 69.68 65.90 62.96 60.58 58.59 55.41 54.11 24.5 90.43 84.15 76.04 70.76 66.92 63.94 61.52 59.50 56.28 54.95 25.0 91.81 85.44 77.20 71.84 67.95 64.92 62.46 60.41 57.14 55.79 EM170APM070007.DGN Radius of Relative Stiffness Figure 7.10 EFFECTIVITY: ALL Section 7 Page 7-15 Dec08/03 b-apm1346