Economy of concrete structures begins in the design development
stage with designers who have a good understanding of formwork
logic. Often, two or more structural alternatives will meet the design
objective equally well. However, one alternative may be significantly
less expensive to build. Constructability, that is, making structural
frames faster, simpler, and less costly to build, must begin in the earliest
phase of the design effort.
Economy in formwork begins with the design of a structure and
continues through the selection of form materials, erection, stripping,
care of forms between reuses, and reuse of forms, if any. When a
building is designed, consideration should be given to each of the
following methods of reducing the cost of formwork:
1. Prepare the structural and architectural designs simultaneously.
If this is done, the maximum possible economy in
formwork can be ensured without sacrificing the structural
and architectural needs of the building.
2. At the time a structure is designed, consider the materials
and methods that will be required to make, erect, and remove
the forms. A person or computer-aided drafting and design
(CADD) operator can easily draw complicated surfaces, connections
between structural members, and other details;
however, making, erecting, and removing the formwork may
3. If patented forms are to be used, design the structural members
to comply with the standard dimensions of the forms
that will be supplied by the particular form supplier who will
furnish the forms for the job.
4. Use the same size of columns from the foundation to the roof,
or, if this is impracticable, retain the same size for several
floors. Adopting this practice will permit the use of beam and
column forms without alteration.
5. Space columns uniformly throughout the building as much
as possible or practicable. If this is not practicable, retaining
the same position from floor to floor will result in economy.
6. Where possible, locate the columns so that the distances between
adjacent faces will be multiples of 4 ft plus 1 in., to permit the
unaltered use of 4-ft-wide sheets of plywood for slab decking.
7. Specify the same widths for columns and column-supported
girders to reduce or eliminate the cutting and fitting of girder
forms into column forms.
8. Specify beams of the same depth and spacing on each floor
by choosing a depth that will permit the use of standard sizes of
lumber, without ripping, for beam sides and bottoms, and
for other structural members.
It is obvious that a concrete structure is designed to serve specific
purposes, that is, to resist loads and deformations that will be applied
to the structure, and to provide an appearance that is aesthetically
pleasing. However, for such a structure, it frequently is possible to
modify the design slightly to achieve economy without impairing the
usability of the structure. The designer can integrate constructability
into the project by allowing three basic concepts: design repetition,
dimensional standards, and dimensional consistency. Examples of
these concepts, excerpted from ref. , are presented in this chapter
to illustrate how economy in formwork may be affected.
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