Use table 3-2 or table 3-3 (depending on type of waler system) to determine the tie spacing based on the ULW. This number is the maximum tie spacing in inches based on wale size.
Tie wires or snap ties (depends on what system you use) must be installed at the intersection of studs and wales. Place the first tie at one half of the maximum tie spacing from the end of the wale.
To determine the number of studs on one side of a form, you need to divide the form length by the maximum stud spacing, and add one for a starter. The first and last stud must be placed at each end of the form.
To determine the number of wales for one side of a form, you must divide the form height by the maximum wale spacing and round up to the next whole number. Place the first wale one half of the maximum space up from the bottom and the remainder at the maximum wale spacing.
To determine the time required to place concrete, you divide the height of the form by the rate of placement. This does NOT include the length of the form. For example, wall height of the form is 10 feet and the vertical rate of placement is 5 feet/hour. Your answer is 2 hours. Figure 3-2 shows how you can estimate man-hours per cubic yard in most situations. These estimates are based on Seabee experiences.
*The following rules apply to figure 3-2:
1. For each 40 feet wheeled, add 25 percent.
2. For upper stories, add per story: Placed by pump, 7 percent; placed by bucket or crane, 5 percent.
3. Construction that moves in and out of ramps, runways, or staging is not included. For moving in and out use 0.22 man-hours per linear foot.
4. Major items of consideration in planning concrete placement are: method of placement, accessibility, the rate of placement in regard to form design and the amount and frequency of delivery is governed by the ability to screed, tamp, and finish.
BRACES are used against wall forms (fig. 3-3) to keep the forms in place and in alignment from mishaps due to external forces, such as wind, personnel, equipment, vibration, and accidents. For most military applications, this force is assumed to be 12.5 times the wall height, in feet. Braces (normally 2 by 4s) to be used should be equally strong in tension as in compression strength, or braces should be used on both sides of a wall form.
Designing wall forms and the bracing for wall forms should be left to the engineers. We do not have the time or the space in this section to cover all the formulas necessary to design forms. Refer to the
Figure 3-2. - Placing concrete labor estimates from P-405.Continue Reading