The use of metal supports to hold beam-
reinforcing steel in position is shown in figure 7-27.
Note the position of the beam bolster. The stirrups are
tied to the main reinforcing steel with a snap tie.
Whenever possible, you should assemble the stirrups
and main reinforcing steel outside the form and then
place the assembled unit in position. Wood blocks
should be substituted for the metal supports only if
there is no possibility of the concrete becoming wet or
if the construction is known to be temporary. Precast
concrete blocks, as shown in figure 7-23, may be
substituted for metal supports or, if none of the types
of bar supports described above seem suitable, the
method shown in figure 7-24 may be used.
Placement of steel in walls is the same as for
columns except that the steel is erected in place and
not preassembled. Horizontal steel is tied to vertical
steel at least three times in any bar length. Steel in
place in a wall is shown in figure 7-28. The wood
block is removed when the form has been filled up to
the level of the block. For high walls, ties in between
the top and bottom should be used.
Steel is placed in footings very much as it is
placed in floor slabs.
Stones, rather than steel
supports, may be used to support the steel at the
Figure 7-27.-Beam-reinforcing steel supported on beam
Figure 7-28.-Steel in place in a wall.
proper distance above the subgrade. Steel mats are
generally preassembled and placed in small footings
after the forms have been set. A typical arrangement
is shown in figure 7-29. Steel mats in large footings
are generally constructed in place.
Welded wire fabric (figure 7-30) is also used as
limited reinforcement for concrete footings, walls,
and slabs, but its primary use is to control crack
widths due to temperature changes.
Form construction for each job has its peculiari-
ties. However, certain natural conditions prevail in all
situations. Wet concrete always develops hydrostatic
pressure and strain on forms. Therefore, all stakes,
Figure 7-29.-Steel in place in a footing.