the concrete of the base. For all other footings the amount of concrete is computed by obtaining the product of the length, width, and height for the various blocks or sections. For the isolated pyramidal footing the horizontal projection of the footing plus 60% is used as the unit of form-area. For example, a footing 10 ft square is considered to have 160 sq ft of forms. This is a purely arbitrary method, but it has been found to work well in practice. For the stepped and combined 3'.9" 1'-0" 6'-6" Finish 1st Floor 6- Rods 7-% Rods 6-% Dowels Building Fig. 3 footing and for all wall-footings, the CONTACT-AREA of the sides is taken as the form-area. The steel is always tabulated by weight for each type of footing. For example, in Fig. 1, there are shown twelve wall column footings, exclusive of those at the corners of the building. The tabulation of the quantities is as follows: = Concrete-volume. (12: 4) 6.5 × 5.33 × 1.25 ft 43.3 cu ft 4.5 X 3.33 X 1.00 ft = 15.0 cu ft Total for each footing = 58.3 cu ft. In the above computations the dimensions of the rectangular blocks comprising the footing are expressed in feet, and scaled in the order of length, width, and height. in which 23.66 ft and 15.66 ft are the perimeters respectively of the lower and upper blocks constituting the wall footing and 1.25 ft and 1.00 ft the heights of the blocks. Total for twelve footings = 12 X 45.3 sq ft = 543 sq ft. Steel-weight. Weight of horizontal reinforcement in each footing = [(7 × 4.83 ft) + (6 x 6.00 ft)] × 0.66 lb = 46.2 lb in which 7 is the number of rods running parallel to the short dimension, and 4.83 the length in feet of each rod; 6 is the number of rods running parallel to the long dimension, 6.00 the length in feet of each rod, and 0.66 the weight in pounds per linear foot of a 12-in round rod. Weight of dowels in each footing = 6 X 7.75 ft X 1.50 lb = 69.8 lb in which 6 is the number of dowels in each footing, each dowel being 7.75 long and weighing 1.50 lb per lin ft (for 3/4-in rounds). The quantities for the corner footings are computed in a similar manner. Table I. Weights of Square Bars and Round Rods Size, in inches 516 3% 716 916 % 116 341316 7% 1516 1 1% 14 Round rods.. 0.17 0.26 0.380.51 0.67 0.851.041.261.50 1.762.042.352.673.384.17 Square bars.. 0.21 0.33 0.48 0.65 0.85 1.081.33 1.611.912.252.612.993.404.305.31 Again referring to the drawings on pages 358 and 360 eight interior column footings are found for which the tabulation of quantities is as follows: Concrete-volume of the base: In the above computations 2.5 ft X 2.5 ft are the dimensions of the top surface of the frustum, 6.25 sq ft is the area of this surface and 1.5 ft is the height of the frustum. in which 1.83 ft X 1.83 ft are the horizontal dimensions of the pedestal and 3.50 ft is its height up to the top of the floor slab. Under some conditions the height might be taken up to the bottom of the floor slab. Total for the eight footings = 8 X 97 cu ft = 776 cu ft. = Form-area for the eight footings = 8 X (7 ft x 7 ft X 1.6) 627 sq ft in which the horizontal projection of the footing plus 60% is taken as an approximate equivalent and function of the form-area. Form-area for the eight pedestals Steel-weight. Weight of horizontal reinforcement in each footing = 8 X (7.33 ft X 3.50 ft) = 205 sq.ft. in which 24 is the number of rods in each footing; 6.5 the length in feet of each rod, and 0.66 the weight in pounds per linear foot of a 2-in round rod. Weight of dowels in each footing in which 6 is the number of dowels in each footing, each dowel being 8 ft long and The 7. Walls and Partitions. form work for all concrete walls and partitions is taken off as cONTACT AREA; that is, a wall 10 ft long and 5 ft high is considered to have 100 sq ft of FORM-AREA. In computing quantities on a job, when there is a large amount of foundation wall work contiguous to the footings, care must be taken to distinguish between the two, especially if the concrete mixture is different. Ordinarily, foundation walls should include all exterior and interior walls from the top of the footings up to the level of the first floor. Referring to the drawings, pages 358 and 362, the quantities for the exterior foundation walls are: = Concrete-volume. (12: 4). South elevation: Wall, 99 ft X 0.83 ft X 3.33 ft 276 cu ft in which the dimensions of the length, width and height of the wall, up to the bottom of the basement floor, are expressed in feet. If the basement floor is not poured immediately subsequent to the foundation wall or if the mixture is appreciably different the latter should be computed up to the level of the TOP of the basement floor, the area of which would then be taken INSIDE of the exterior walls. = 19 cu ft. Pilasters, 4 X (2.5 ft X 0.50 ft X 3.75 ft) West elevation: Wall, 57.33 ft X 0.83 ft X 3.33 ft = 158 cu ft in which the length 57.33 equals (59 ft — 1 ft 8 in), which deduction is made in order to avoid duplication at the corners. www Pilasters, 2 X (2.5 × 0.50 X 3.75 ft) = 9 cu ft North elevation is the same as the south elevation=295 cu ft. = 167 cu ft. Four corner piers (additional concrete) 4 X [(2.50 X 2.50 ft) (2.00 2.00 ft)] X 3.75 ft = 34 cu ft In the above computations 2.50 × 2.50 ft is the gross sectional area of the pier and 2.00 2.00 ft is the portion notched out upon the interior and already included in the concrete of the wall. Total concrete-volume in exterior foundation walls = 958 cu ft. South elevation: Wall, 2 X (99 × 3.33 ft) first figure, 2, signifies that both sides of the wall 3.33 ft is taken up to the bottom of the floor slab. Sides of pilasters 4 × (2 × 0.50 X 3.33 ft) are four pilasters each formed on two sides, the height again taken to the bottom of the floor slab. = 659 sq ft in which the are formed. The height, = 13 sq ft in which there offset being 0.50 ft and the As the forms are computed only up to the bottom of the ground floor it is necessary to add a strip of form-work around the edge of the floor. Including an allowance for forming around the pilasters this area is Face of floor supported on the ground [(2 x 105 ft) + (2 × 63 ft)] × 0.42 ft 141 sq ft in which 0.42 is the thickness, 5 in, expressed as a decimal of a foot. If the basement floor is not poured immediately subsequent to the foundation wall, an allowance must be made for forming the inside face through a height represented by the floor thickness. In other words, both exterior and interior forms would be computed up to the TOP of the basement floor. Total form work in exterior foundation walls = 2 288 sq ft. |