Table 9.2 was used to select the formwork system for the exterior ‘‘wall.’’ The selection was a self-raising form for the following reasons:
1. The self-raising form is suitable for buildings higher than 25 stories.
2. It can accommodate architectural concrete requirements.
3. The self-raising form is a crane-independent system which is suitable for restricted site conditions.
This case study was extracted from an article entitled ‘‘Building Production and Quality into Architectural Concrete.’’ The whole article was devoted to the problem of selecting the formwork system. The author is an expert in selecting formwork systems and he attributed his selection to the same reasons stated above. In his article, he explained that renting or buying another crane was impossible because of the site conditions in ‘‘downtown Denver.’’ It was also economically unfeasible.
[1] Dimension: 2 in. < thickness < 4 in. and width > 2 in.
[2] Beams and stringers: thickness > 5 in. and width > thickness + 2 in.
[3] Southern Pine Inspection Bureau
[4] Check local suppliers for availability before specifying Plyform Class II grade, as it is rarely manufactured.
[5] When exterior glue is specified, i. e. Exposure 1, stress level 2 (S-2) should be used.
[6] Properties and stresses apply only to APA RATED STURD-I-FLOOR and APA RATED SHEATHING manufactured entirely with veneers.
[7] APA RATED STURD-I-FLOOR 2-4-1 may be produced unsanded.
[8] May be available as Structural I. For such designation use Group 1 stresses and Table 2 section properties.
[9] C face and back must be natural unrepaired; if repaired, use stress level 2 (S-2).
[10] Type: APA B-B plyform class I with species group of face
ply = 2.
• Dry conditions.
• Thickness: 11/8 in.
[11] Consider 1-ft strip. It carries a load of 180 x 1 =
180 lb/ft.
[12] Dimension: 2 in. < thickness < 4 in. and width > 2 in.
[13] Beams and stringers: thickness > 5 in. and width > thickness + 2 in.
[14] Southern Pine Inspection Bureau
[15] Check local suppliers for availability before specifying Plyform Class II grade, as it is rarely manufactured.
[16] Type: APA B-B plyform class I with species group of face
ply = 2.
• Dry conditions.
• Thickness: 11/8 in.
[17] Consider 1-ft strip. It carries a load of 180 x 1 =
180 lb/ft.
[18] Fabrication of the flying formwork is normally performed on the ground, which yields higher productivity. Stripping flying formwork as one integral unit reduces the stripping costs to approximately 50 percent of the stripping costs for hand-set formwork systems such as conventional wood and conventional metal systems. Stripping of hand-set systems is performed by removing small pieces, which results in rather high labor costs.
[19] Loads are transformed by telescoping extension legs located underneath the aluminum trusses and thus giving enough working space below the formwork to allow other
[20] I = 5.358 in.4
• S = 3.063 in.3
• d = 3.5 in.
• A = 5.25 in.2
Bending
Size factor Cf = 1.5
F’ = allowable stress = F^s) (Ct)(CD)(Cf)
[21] The forms may be designed for almost any plan, shape, and size structure.
• The forms can be easily adjusted during construction to accommodate changes in wall thickness.
• The application of form liners provides numerous architectural finishes.
• Forms can be reused approximately 50 times or more.
• The formwork system is preassembled, therefore makeup area is not necessary.