3 Slab Form Design 3.1 Properties of Form Materials 3.2 Properties of Area 3.3 Properties of Sawn Lumber 3.4 Properties of Plywood 3.5 Slab Form Design 3.6 Design Steps Concrete forms are engineered structures that are required to sup- port loads composed of fresh concrete, construction materials, equipment, workers, impact of various kinds, and sometimes wind. The forms must support all the applied loads without collapse or excessive deflection. ACI Committee Report 347-1994 defines those applied loads and gives a number of guidelines for safety and serviceability. Based on these guidelines, a number of design tables have been developed for the design of concrete formwork. These tables are useful design tools. However, they do not take into consideration stress modification factors that are provided by the National Design Specification for Wood Construction, NDS 1991. This chapter presents a design procedure for all-wood con- crete slab forms based on NDS 1991 and Plywood Design Specifi- cation 1997. The objective of the formwork design is to determine the safe spacing for each slab form component (sheathing, joists, stringers, and shores), and ensure that each component has adequate strength to resist the applied pressure without exceeding predeter- mined allowable deflection. 3.1 PROPERTIES OF FORM MATERIALS The following sections provide an overview of some important properties of structural sections that are used in formwork design. Readers familiar with these expressions should start with Section 3.3. 48 Chapter 3 3.2 PROPERTIES OF AREA Certain mathematical expressions of the properties of sections are used in design calculations for various design shapes and loading conditions. These properties include the moment of inertia, cross sectional area, neutral axis, section modulus, and radius of gyra- tion of the design shape in question. These properties are de- scribed below. 1. Moment of inertia. The moment of inertia I of the cross section is defined as the sum of the products of the differ- ential areas into which the section may be divided, multi- plied by the squares of their distances from the neutral axis of the section (Figure 3.1). If the section is subjected to a bending moment about the X-X axis of the cross section, the moment of inertia about X-X is denoted by I xx , I xx ϭ Α n iϭ1 A i Y 2 i where n ϭ total number of differential areas A i ϭ area of element i Y i ϭ distance between element i and X-X axis If the member is subjected to a bending moment about axis Y-Y of the cross section, we denote the moment of inertia associated with it as I yy , I yy ϭ Α m jϭ1 A j X 2 j where m ϭ total number of elementary areas A j ϭ area of element j X j ϭ distance between element j and Y-Y axis Slab Form Design 49 Figure 3.1 Moment-of-inertia calculation. 2. Cross sectional area. This is the area of a section taken through the member, perpendicular to its longitudinal axis. 3. Neutral axis. The neutral axis is a line through the cross section of the member along which the fibers sustain nei- ther tension nor compression when subjected to a loading. 4. Section modulus. Denoted as S, this is the moment of iner- tia divided by the distance between the neutral axis and the extreme fibers (maximum stressed fibers) of the cross section. If c is the distance from the neutral axis to the extreme 50 Chapter 3 fibers in inches, one can write: S xx ϭ I xx c S yy ϭ I yy c 5. Radius of gyration. This property, denoted as r, is the square root of the quantity of the moment of inertia di- vided by the area of the cross section. r xx ϭ √ I xx A r yy ϭ √ I yy A Here r xx and r yy are the radii of gyration about X-X and Y-Y axes, respectively. 3.2.1 Rectangular Cross Section The most commonly used cross section in the design of formwork is the rectangular cross section with breadth b and depth d (Figure 3.2). These are usually measured in the units of inches or millime- ters. Figure 3.2 Rectangular cross section. Slab Form Design 51 For rectangular cross section, the formulas discussed in the previous section take the forms: Moments of intertia: I xx ϭ bd 3 12 , in. 4 or mm 4 I yy ϭ db 3 12 , in. 4 or mm 4 Radii of gyration: r xx ϭ √ I xx A ϭ d √ 12 , in. or mm r yy ϭ √ I yy A ϭ b √ 12 , in. or mm Section modules: S xx ϭ I xx c ϭ bd 2 6 , in. 3 or mm 3 ΂ here c ϭ d 2 ΃ S yy ϭ I yy c ϭ db 2 6 , in. 3 or mm 3 ΂ here c ϭ b 2 ΃ The section properties for selected standard sizes of board, dimension lumber, and timbers are given in Table 3.1. The values given in this table can be used to calculate the properties given above. Table 3.2 provides section properties of standard dressed (S4S) sawn lumber. 3.3 PROPERTIES OF SAWN LUMBER 3.3.1 Classification of Sawn Lumber Structural Sawn Lumber size classification was discussed in Chap- ter 1 and is summarized below. 1. Dimension: 2 in. Ͻ thickness Ͻ 4 in. and width Ͼ 2 in. 2. Beams and stringers: thickness Ͼ 5 in. and width Ͼ thickness ϩ 2 in. 52 Chapter 3 Table 3.1 Nominal and Minimum Dressed Sizes of Sawn Lumber Thickness (in.) Face widths (in.) Minimum Minimum dressed dressed Item Nominal Dry Green Nominal Dry Green Boards 1 3/4 25/32 2 1-1/2 1-9/16 1-1/4 1 1-1/32 3 2-1/2 2-9/16 1-1/2 1-1/4 1-9/32 4 3-1/2 3-9/16 5 4-1/2 4-5/8 6 5-1/2 5-5/8 7 6-1/2 6-5/8 8 7-1/4 7-1/2 9 8-1/4 8-1/2 10 9-1/4 9-1/2 11 10-1/4 10-1/2 12 11-1/4 11-1/2 14 13-1/4 13-1/2 16 15-1/4 15-1/2 Dimension 2 1-1/2 1-9/16 2 1-1/2 1-9/16 Lumber 2-1/2 2 2-1/16 3 2-1/2 2-9/16 3 2-1/2 2-9/12 4 3-1/2 3-9/16 3-1/2 3 3-1/16 5 4-1/2 4-5/8 6 5-1/2 5-5/8 8 7-1/4 7-1/2 10 9-1/4 9-1/2 12 11-1/4 11-1/2 14 13-1/4 13-1/2 16 15-1/4 15-1/2 Dimension 4 3-1/2 3-9/16 2 1-1/2 1-9/16 Lumber 4-1/2 4 4-1/16 3 2-1/2 2-9/16 4 3-1/2 3-9/16 5 4-1/2 4-5/8 6 5-1/2 5-5/8 8 7-1/4 7-1/2 10 9-1/4 9-1/2 12 11-1/4 11-1/2 14 — 13-1/2 16 — 15-1/2 Timbers 5 and — 1/2 off 5 and — 1/2 off thicker wider From National Design Specification for Wood Construction 1991 Slab Form Design 53 Table 3.2 Section Properties of Standard Dressed (S4S) Sawn Lumber Standard X-X-AXIS Y-Y-AXIS dressed Approximate weight in pounds per linear foot (lb/ft) Nominal size (S4S) Area of Section Moment Section Moment of piece when density of wood equals: size b ϫ d Section modulus of inertia modulus of inertia b ϫ d inches ϫ inches A in 2 S xx in 3 I xx in 4 S yy in 3 I yy in 4 25 lb/ft 3 30 lb/ft 3 35 lb/ft 3 40 lb/ft 3 45 lb/ft 3 50 lb/ft 3 1 ϫ 33/4ϫ 2-1/2 1.875 0.781 0.977 0.234 0.088 0.326 0.391 0.456 0.521 0.586 0.651 1 ϫ 43/4ϫ 3-1/2 2.625 1.531 2.680 0.328 0.123 0.456 0.547 0.638 0.729 0.820 0.911 1 ϫ 63/4ϫ 5-1/2 4.125 3.781 10.40 0.516 0.193 0.716 0.859 1.003 1.146 1.289 1.432 1 ϫ 83/4ϫ 7-1/4 5.438 6.570 23.82 0.680 0.255 0.944 1.133 1.322 1.510 1.699 1.888 1 ϫ 10 3/4 ϫ 9-1/4 6.938 10.70 49.47 0.867 0.325 1.204 1.445 1.686 1.927 2.168 2.409 1 ϫ 12 3/4 ϫ 11-1/4 8.438 15.82 88.99 1.055 0.396 1.465 1.758 2.051 2.344 2.637 2.930 2 ϫ 3 1-1/2 ϫ 2-1/2 3.750 1.563 1.953 0.938 0.703 0.651 0.781 0.911 1.042 1.172 1.302 2 ϫ 4 1-1/2 ϫ 3-1/2 5.250 3.063 5.359 1.313 0.984 0.911 1.094 1.276 1.458 1.641 1.823 2 ϫ 5 1-1/2 ϫ 4-1/2 6.750 5.063 11.39 1.688 1.266 1.172 1.406 1.641 1.875 2.109 2.344 2 ϫ 6 1-1/2 ϫ 5-1/2 8.250 7.563 20.80 2.063 1.547 1.432 1.719 2.005 2.292 2.578 2.865 2 ϫ 8 1-1/2 ϫ 7-1/4 10.88 13.14 47.63 2.719 2.039 1.888 2.266 2.643 3.021 3.398 3.776 2 ϫ 10 1-1/2 ϫ 9-1/4 13.88 21.39 98.93 3.469 2.602 2.409 2.891 3.372 3.854 4.336 4.818 2 ϫ 12 1-1/2 ϫ 11-1/4 16.88 31.64 178.0 4.219 3.164 2.930 3.516 4.102 4.688 5.273 5.859 2 ϫ 14 1-1/2 ϫ 13-1/4 19.88 43.89 290.8 4.969 3.727 3.451 4.141 4.831 5.521 6.211 6.901 3 ϫ 4 2-1/2 ϫ 3-1/2 8.750 5.104 8.932 3.646 4.557 1.519 1.823 2.127 2.431 2.734 3.038 3 ϫ 5 2-1/2 ϫ 4-1/2 11.25 8.438 18.98 4.688 5.859 1.953 2.344 2.734 3.125 3.516 3.906 3 ϫ 6 2-1/2 ϫ 5-1/2 13.75 12.60 34.66 5.729 7.161 2.387 2.865 3.342 3.819 4.297 4.774 3 ϫ 8 2-1/2 ϫ 7-1/4 18.13 21.90 79.39 7.552 9.440 3.147 3.776 4.405 5.035 5.664 6.293 3 ϫ 10 2-1/2 ϫ 9-1/4 23.13 35.65 164.9 9.635 12.04 4.015 4.818 5.621 6.424 7.227 8.030 3 ϫ 12 2-1/2 ϫ 11-1/4 28.13 52.73 296.6 11.72 14.65 4.883 5.859 6.836 7.813 8.789 9.766 3 ϫ 14 2-1/2 ϫ 13-1/4 33.13 73.15 484.6 13.80 17.25 5.751 6.901 8.051 9.201 10.35 11.50 3 ϫ 16 2-1/2 ϫ 15-1/4 38.13 96.90 738.9 15.89 19.86 6.619 7.943 9.266 10.59 11.91 13.24 4 ϫ 4 3-1/2 ϫ 3-1/2 12.25 7.146 12.51 7.146 12.51 2.127 2.552 2.977 3.403 3.828 4.253 4 ϫ 5 3-1/2 ϫ 4-1/2 15.75 11.81 26.58 9.188 16.08 2.734 3.281 3.828 4.375 4.922 5.469 4 ϫ 6 3-1/2 ϫ 5-1/2 19.25 17.65 48.53 11.23 19.65 3.342 4.010 4.679 5.347 6.016 6.684 4 ϫ 8 3-1/2 ϫ 7-1/4 25.38 30.66 111.1 14.80 25.90 4.405 5.286 6.168 7.049 7.930 8.811 4 ϫ 10 3-1/2 ϫ 9-1/4 32.38 49.91 230.8 18.89 33.05 5.621 6.745 7.869 8.993 10.12 11.24 4 ϫ 12 3-1/2 ϫ 11-1/4 39.38 73.83 415.3 22.97 40.20 6.836 8.203 9.570 10.94 12.30 13.67 4 ϫ 14 3-1/2 ϫ 13-1/2 47.25 106.3 717.6 27.56 48.23 8.203 9.844 11.48 13.13 14.77 16.41 4 ϫ 16 3-1/2 ϫ 15-1/2 54.25 140.1 1086.1 31.64 55.38 9.42 11.30 13.19 15.07 16.95 18.84 54 Chapter 3 Table 3.2 Continued Standard X-X-AXIS Y-Y-AXIS dressed Approximate weight in pounds per linear foot (lb/ft) Nominal size (S4S) Area of Section Moment Section Moment of piece when density of wood equals: size b ϫ d Section modulus of inertia modulus of inertia b ϫ d inches ϫ inches A in 2 S xx in 3 I xx in 4 S yy in 3 I yy in 4 25 lb/ft 3 30 lb/ft 3 35 lb/ft 3 40 lb/ft 3 45 lb/ft 3 50 lb/ft 3 5 ϫ 5 4-1/2 ϫ 4-1/2 20.25 15.19 34.17 15.19 34.17 3.516 4.219 4.922 5.625 6.328 7.031 6 ϫ 6 5-1/2 ϫ 5-1/2 30.25 27.73 76.26 27.73 76.26 5.252 6.302 7.352 8.403 9.453 10.50 6 ϫ 8 5-1/2 ϫ 7-1/2 41.25 51.56 193.4 37.81 104.0 7.161 8.594 10.03 11.46 12.89 14.32 6 ϫ 10 5-1/2 ϫ 9-1/2 52.25 82.73 393.0 47.90 131.7 9.071 10.89 12.70 14.51 16.33 18.14 6 ϫ 12 3-1/2 ϫ 11-1/2 63.25 121.2 697.1 57.98 159.4 10.98 13.18 15.37 17.57 19.77 21.96 6 ϫ 14 5-1/2 ϫ 13-1/2 74.25 167.1 1128 68.06 187.2 12.89 15.47 18.05 20.63 23.20 25.78 6 ϫ 16 5-1/2 ϫ 15-1/2 85.25 220.2 1707 78.15 214.9 14.80 17.76 20.72 23.68 26.64 29.60 6 ϫ 18 5-1/2 ϫ 17-1/2 96.25 280.7 2456 88.23 242.6 16.71 20.05 23.39 26.74 30.08 33.42 6 ϫ 20 5-1/2 ϫ 19-1/2 107.3 348.6 3398 98.31 270.4 18.62 22.34 26.07 29.79 33.52 37.24 6 ϫ 22 5-1/2 ϫ 21-1/2 118.3 423.7 4555 108.4 298.1 20.53 24.64 28.74 32.85 36.95 41.06 6 ϫ 24 5-1/2 ϫ 23-1/2 129.3 506.2 5948 118.5 325.8 22.44 26.93 31.41 35.90 40.39 44.88 8 ϫ 8 7-1/2 ϫ 7-1/2 56.25 70.31 263.7 70.31 263.7 9.766 11.72 13.67 15.63 17.58 19.53 8 ϫ 10 7-1/2 ϫ 9-1/2 71.25 112.8 535.9 89.06 334.0 12.37 14.84 17.32 19.79 22.27 24.74 8 ϫ 12 7-1/2 ϫ 11-1/2 86.25 165.3 950.5 107.8 404.3 14.97 17.97 20.96 23.96 26.95 29.95 8 ϫ 14 7-1/2 ϫ 13-1/2 101.3 227.8 1538 126.6 474.6 17.58 21.09 24.61 28.13 31.64 35.16 8 ϫ 16 7-1/2 ϫ 15-1/2 116.3 300.3 2327 145.3 544.9 20.18 24.22 28.26 32.29 36.33 40.36 8 ϫ 18 7-1/2 ϫ 17-1/2 131.3 382.8 3350 164.1 615.2 22.79 27.34 31.90 36.46 41.02 45.57 8 ϫ 20 7-1/2 ϫ 19-1/2 146.3 475.3 4634 182.8 685.5 25.39 30.47 35.55 40.63 45.70 50.78 8 ϫ 22 7-1/2 ϫ 21-1/2 161.3 577.8 6211 201.6 755.9 27.99 33.59 39.19 44.79 50.39 55.99 8 ϫ 24 7-1/2 ϫ 23-1/2 176.3 690.3 8111 220.3 826.2 30.60 36.72 42.84 48.96 55.08 61.20 10 ϫ 10 9-1/2 ϫ 9-1/2 90.25 142.9 678.8 142.9 678.8 15.67 18.80 21.94 25.07 28.20 31.34 10 ϫ 12 9-1/2 ϫ 11-1/2 109.3 209.4 1204 173.0 821.7 18.97 22.76 26.55 30.35 34.14 37.93 10 ϫ 14 9-1/2 ϫ 13-1/2 128.3 288.6 1948 203.1 964.5 22.27 26.72 31.17 35.63 40.08 44.53 10 ϫ 16 9-1/2 ϫ 15-1/2 147.3 380.4 2948 233.1 1107 25.56 30.68 35.79 40.90 46.02 51.13 10 ϫ 18 9-1/2 ϫ 17-1/2 166.3 484.9 4243 263.2 1250 28.86 34.64 40.41 46.18 51.95 57.73 10 ϫ 20 9-1/2 ϫ 19-1/2 185.3 602.1 5870 293.3 1393 32.16 38.59 45.03 51.46 57.89 64.32 10 ϫ 22 9-1/2 ϫ 21-1/2 204.3 731.9 7868 323.4 1536 35.46 42.55 49.64 56.74 63.83 70.92 10 ϫ 24 9-1/2 ϫ 23-1/2 223.3 874.4 10270 353.5 1679 38.76 46.51 54.26 62.01 69.77 77.52 Slab Form Design 55 12 ϫ 12 11-1/2 ϫ 11-1/2 132.3 253.5 1458 253.5 1458 22.96 27.55 32.14 36.74 41.33 45.92 12 ϫ 14 11-1/2 ϫ 13-1/2 155.3 349.3 2358 297.6 1711 26.95 32.34 37.73 43.13 48.52 53.91 12 ϫ 16 11-1/2 ϫ 15-1/2 178.3 460.5 3569 341.6 1964 30.95 37.14 43.32 49.51 55.70 61.89 12 ϫ 18 11-1/2 ϫ 17-1/2 201.3 587.0 5136 385.7 2218 34.94 41.93 48.91 55.90 62.89 69.88 12 ϫ 20 11-1/2 ϫ 19-1/2 224.3 728.8 7106 429.8 2471 38.93 46.72 54.51 62.29 70.08 77.86 12 ϫ 22 11-1/2 ϫ 21-1/2 247.3 886.0 9524 473.9 2725 42.93 51.51 60.10 68.68 77.27 85.85 12 ϫ 24 11-1/2 ϫ 23-1/2 270.3 1058 12440 518.0 2978 46.92 56.30 65.69 75.07 84.45 93.84 14 ϫ 14 13-1/2 ϫ 13-1/2 182.3 410.1 2768 410.1 2768 31.64 37.97 44.30 50.63 56.95 63.28 14 ϫ 16 13-1/2 ϫ 15-1/2 209.3 540.6 4189 470.8 3178 36.33 43.59 50.86 58.13 65.39 72.66 14 ϫ 18 13-1/2 ϫ 17-1/2 236.3 689.1 6029 531.6 3588 41.02 49.22 57.42 65.63 73.83 82.03 14 ϫ 20 13-1/2 ϫ 19-1/2 263.3 855.6 8342 592.3 3998 45.70 54.84 63.98 73.13 82.27 91.41 14 ϫ 22 13-1/2 ϫ 21-1/2 290.3 1040 11180 653.1 4408 50.39 60.47 70.55 80.63 90.70 100.8 14 ϫ 24 13-1/2 ϫ 23-1/2 317.3 1243 14600 713.8 4818 55.08 66.09 77.11 88.13 99.14 110.2 16 ϫ 16 15-1/2 ϫ 15-1/2 240.3 620.6 4810 620.6 4810 41.71 50.05 58.39 66.74 75.08 83.42 16 ϫ 18 15-1/2 ϫ 17-1/2 271.3 791.1 6923 700.7 5431 47.09 56.51 65.93 75.35 84.77 94.18 16 ϫ 20 15-1/2 ϫ 19-1/2 302.3 982.3 9578 780.8 6051 52.47 62.97 73.46 83.96 94.45 104.9 16 ϫ 22 15-1/2 ϫ 21-1/2 333.3 1194 12840 860.9 6672 57.86 69.43 81.00 92.57 104.1 115.7 16 ϫ 24 15-1/2 ϫ 23-1/2 364.3 1427 16760 941.0 7293 63.24 75.89 88.53 101.2 113.8 126.5 18 ϫ 18 17-1/2 ϫ 17-1/2 306.3 893.2 7816 893.2 7816 53.17 63.80 74.44 85.07 95.70 106.3 18 ϫ 20 17-1/2 ϫ 19-1/2 341.3 1109 10810 995.3 8709 59.24 71.09 82.94 94.79 106.6 118.5 18 ϫ 22 17-1/2 ϫ 21-1/2 376.3 1348 14490 1097 9602 65.32 78.39 91.45 104.5 117.6 130.6 18 ϫ 24 17-1/2 ϫ 23-1/2 411.3 1611 18930 1199 10500 71.40 85.68 99.96 114.2 128.5 142.8 20 ϫ 20 19-1/2 ϫ 19-1/2 380.3 1236 12050 1236 12050 66.02 79.22 92.42 105.6 118.8 132.0 20 ϫ 22 19-1/2 ϫ 21-1/2 419.3 1502 16150 1363 13280 72.79 87.34 101.9 116.5 131.0 145.6 20 ϫ 24 19-1/2 ϫ 23-1/2 458.3 1795 21090 1489 14520 79.56 95.47 111.4 127.3 143.2 159.1 22 ϫ 22 21-1/2 ϫ 21-1/2 462.3 1656 17810 1656 17810 80.25 96.30 112.4 128.4 144.5 160.5 22 ϫ 24 21-1/2 ϫ 23-1/2 505.3 1979 23250 1810 19460 87.72 105.3 122.8 140.3 157.9 175.4 24 ϫ 24 23-1/2 ϫ 23-1/2 552.3 2163 25420 2163 25420 95.88 115.1 134.2 153.4 172.6 191.8 From National Design Specification for Wood Construction 1991 [...]... HEMLOCK-TAMARACK 2 -4 ″ thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide * Northeastern Lumber Manufacturers Association ** Northern Softwood Lumber Bureau Chapter 3 Select Structural No 1 No 2 No 3 Stud Construction Standard Utility EASTERN SOFTWOODS 2 -4 ″ thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide 1250 775 575 35 0 450 675 37 5 175 575 35 0 275 150 200 30 0 175 75 70 70 70 70 70 70 70 70 33 5 33 5 33 5 33 5 33 5 33 5 33 5 33 5... 70 70 70 33 5 33 5 33 5 33 5 33 5 33 5 33 5 33 5 1200 1050 975 550 600 1200 1000 650 1 ,30 0,000 1,200,000 1,100,000 NELMA 1,000,000 NSLB 1,000,000 WCLIB 1,000,000 WWPA 900,000 900,000 SPRUCE-PINE-FIR (SOUTH) 2 -4 ″ thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide Chapter 3 Select Structural No 1 No 2 No 3 Stud Construction Standard Utility Select Structural No 1 No 2 No 3 Stud Construction Standard Utility 2 -4 ″ thick... thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide 1000 725 700 400 550 800 450 225 600 425 425 250 32 5 475 275 125 75 75 75 75 75 75 75 75 425 425 425 425 425 425 425 425 1000 825 650 37 5 400 850 650 425 1,100,000 1,000,000 1,000,000 900,000 WCLIB 900,000 WWPA 900,000 800,000 800,000 875 650 650 37 5 500 725 400 200 400 30 0 275 175 225 32 5 175 75 70 70 70 70 70 70 70 70 33 5 33 5 33 5 33 5 33 5 33 5 33 5 33 5 1050 925 875... Structural No 1 No 2 No 3 Stud Construction Standard Utility 2 -4 ″ thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide 775 575 550 32 5 425 625 35 0 175 450 32 5 32 5 175 250 37 5 200 100 60 60 60 60 60 60 60 60 37 0 37 0 37 0 37 0 37 0 37 0 37 0 37 0 750 600 475 275 30 0 625 475 32 5 800,000 700,000 700,000 600,000 NELMA 600,000 700,000 600,000 600,000 130 0 925 900 525 700 1050 575 275 750 550 525 30 0 425 600 32 5 150 105 105 105... 2 -4 ″ thick 2 -4 ″ wide 130 0 1000 575 775 1150 625 30 0 775 550 32 5 425 625 35 0 175 75 75 75 75 75 75 75 37 0 37 0 37 0 37 0 37 0 37 0 37 0 1650 1450 850 925 1750 1500 975 1,700,000 1,600,000 1,400,000 NLGA 1,400,000 1,500,000 1,400,000 1 ,30 0,000 1000 725 700 400 550 800 450 225 600 425 425 250 32 5 475 275 125 100 100 100 100 100 100 100 100 620 620 620 620 620 620 620 620 875 700 550 32 5 35 0 725 575 37 5 1 ,30 0,000... 575 35 0 450 675 37 5 175 575 35 0 275 150 200 30 0 175 75 70 70 70 75 70 70 70 70 35 0 35 0 35 0 35 0 35 0 35 0 35 0 35 0 1200 1000 825 475 525 1050 850 550 1,200,000 1,100,000 1,100,000 900,000 NELMA 900,000 NSLB 1,000,000 900,000 800,000 1400 1050 950 850 500 675 975 550 250 900 700 600 500 30 0 400 575 32 5 150 75 75 75 75 75 75 75 75 75 405 405 405 405 405 405 405 405 405 1500 135 0 130 0 1250 725 800 1500 130 0... 800,000 800,000 1400 1000 975 550 750 1100 625 30 0 800 575 575 32 5 450 650 35 0 175 110 110 110 110 110 110 110 110 885 885 885 885 885 885 885 885 1150 925 725 425 450 975 750 500 1,400,000 1,400,000 1 ,30 0,000 1,200,000 NELMA 1,200,000 1,200,000 1,100,000 1,000,000 950 575 35 0 450 675 37 5 175 450 275 150 200 30 0 175 75 65 65 65 65 65 65 65 35 0 35 0 35 0 35 0 35 0 35 0 35 0 1100 825 475 525 1050 850 550 1,100,000... 1,600,000 1,500,000 1 ,30 0,000 NELMA 1 ,30 0,000 1,400,000 1 ,30 0,000 1,200,000 RED MAPLE 2 -4 ″ thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide Chapter 3 Select Structural No 1 No 2 No 3 Stud Construction Standard Utility Select Structural No 1 No 2 No 3 Stud Construction Standard Utility 2 -4 ″ thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide 1150 825 800 475 625 925 525 250 675 500 475 275 37 5 550 30 0 150 85 85 85 85 85... No 1 No 2 No 3 Stud Construction Standard Utility 2 -4 ″ thick 2″ & wider 2 -4 ″ thick 2 -4 ″ wide 67 Table 3. 3a Size Adjustment Factor C F for Visually Graded Dimension Lumber 68 Fb Grades Width (in.) Thickness 2 and 3 in Thickness 4 in Ft Fc Select Structural No 1 and Better No No 2 No 3 2, 3, and 4 5 6 8 10 12 14 and wider 1.5 1.4 1 .3 1.2 1.1 1.0 0.9 1.5 1.4 1 .3 1 .3 1.2 1.1 1.0 1.5 1.4 1 .3 1.2 1.1 1.0... and decking Table 3. 3a through 3. 3d gives the design values along with its adjustment factors for all species except Southern Pine Design values for Southern Pine are shown in Tables 3. 4a through 3. 4d and Table 3. 5 Size Factor Stresses parallel to grain for visually graded dimension lumber should be multiplied by the size factors provided in Tables 3. 3a and 3. 4a 58 Chapter 3 Figure 3. 4 Forces and directions . 1 3- 1 /4 1 3- 1 /2 16 1 5-1 /4 1 5-1 /2 Dimension 2 1-1 /2 1-9 /16 2 1-1 /2 1-9 /16 Lumber 2-1 /2 2 2-1 /16 3 2-1 /2 2-9 /16 3 2-1 /2 2-9 /12 4 3- 1 /2 3- 9 /16 3- 1 /2 3 3- 1 /16 5 4-1 /2 4-5 /8 6 5-1 /2 5-5 /8 8 7-1 /4 7-1 /2 10. 1-1 /2 1-9 /16 1-1 /4 1 1-1 /32 3 2-1 /2 2-9 /16 1-1 /2 1-1 /4 1-9 /32 4 3- 1 /2 3- 9 /16 5 4-1 /2 4-5 /8 6 5-1 /2 5-5 /8 7 6-1 /2 6-5 /8 8 7-1 /4 7-1 /2 9 8-1 /4 8-1 /2 10 9-1 /4 9-1 /2 11 1 0-1 /4 1 0-1 /2 12 1 1-1 /4 1 1-1 /2 14. 7-1 /2 10 9-1 /4 9-1 /2 12 1 1-1 /4 1 1-1 /2 14 1 3- 1 /4 1 3- 1 /2 16 1 5-1 /4 1 5-1 /2 Dimension 4 3- 1 /2 3- 9 /16 2 1-1 /2 1-9 /16 Lumber 4-1 /2 4 4-1 /16 3 2-1 /2 2-9 /16 4 3- 1 /2 3- 9 /16 5 4-1 /2 4-5 /8 6 5-1 /2 5-5 /8 8 7-1 /4