Formwork for Concrete Structures by R.L.Peurifoy and G.D- By EasyEngineering.net

368 Chapter Twelve
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FIGURE 12-4 Installation using adjustable steel forms; typical arrangement of
centering. (Source: Ceco Concrete Construction)
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The standard widths of Longforms are 20 and 30 in., with filler
widths of 10 and 15 in. available for filling nonstandard spaces only.
Figure 12-5 gives the cross-sectional dimensions of the forms. Standard
joist widths are 5 in. for 20-in.-wide Longforms and 6 in. for 30-in.-wide
Longforms. Wider joists can be provided by using special soffit fillers
in increments of ½ in. with either 20- or 30-in.-wide Longforms.
Repetition within a given project is important when using standard
Longform sizes and lengths. In most cases, it is more economical
to vary beam widths, beam tees, or bridging joist widths in order to
maintain typical Longform lengths from floor to floor. As illustrated
in Figure 12-6, the forms are installed with the ends resting on wood
carriers attached to beam forms or to the soffits of bridging joists. The
forms are installed with the soffit flanges held together with C clamps.
Soffit fillers may be used, as shown in Figure 12-6, to produce wider
concrete joists.
FIGURE 12-5 Typical cross sections of Ceco Longforms; all dimensions are
outside to outside. (Source: Ceco Concrete Construction)
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