reinforcing bars. About 12 pounds (5.4 kg) of wire is
required to tie an average ton (0.9 tome) of bars.
NOTE: Tie wire adds nothing to the strength of
A number of different types of ties can be used
with reinforcing bars; some are more effective than
others. Figure 7-17 shows six types of ties that are
identified below according to the letters of the
alphabet used to show individual ties.
A. SNAP TIE or SIMPLE TIE. The wire is simply
wrapped once around the two crossing bars in a
diagonal manner with the two ends on top. These are
twisted together with a pair of sidecutters until they are
very tight against the bars. Then the loose ends of the
wire are cut off. This tie is used mostly on floor slabs.
B. WALL TIE. This tie is made by going about 1
1/2 times around the vertical bar, then diagonally
around the intersection, twisting the two ends together
until the connection is tight, but without breaking the
tie wire, then cutting off the excess. The wall tie is used
on light vertical mats of steel.
C. DOUBLE-STRAND SINGLE TIE. This tie is a
variation of the simple tie. It is especially favored for
D. SADDLE TIE. The wires pass halfway around
one of the ban on either side of the crossing bar and are
brought squarely or diagonally around the crossing bar
with the ends twisted together and cut off. This tie is
used on special locations, such as on walls.
E. SADDLE TIE WITH TWIST. This tie is a
variation of the saddle tie. The tie wire is carried
completely around one of the bars, then squarely across
and halfway around the other, either side of the crossing
bars, and finally brought together and twisted either
squarely or diagonally across. The saddle tie with twist
is used for heavy mats that are to be lifted by a crane.
F. CROSS TIE or FIGURE-EIGHT TIE. This type
of tie has the advantage of causing little or no twist in
The proper location for the reinforcing bars is
usually given on drawings (table 7-7). In order for the
structure to withstand the loads it must carry, place the
steel in the position shown. Secure the bars in position
in such a way that concrete-placing operations will not
move them. This can be accomplished by the use of
the reinforcing bar supports shown in figures 7-18,
7-19, and 7-20.
Figure 7-17.Six types of ties.
Figure 7-18.Reinforcement bar accessories.
The proper coverage of bars in the concrete is very
important to protect the bars from fire hazards,
possibility of corrosion, and exposure to weather.
When not specified, minimum standards given below
and in figure 7-21 should be observed.
FOOTINGS-3 inches at the sides where concrete
is cast against the earth and on the bottoms of footings
or other principal structural members where concrete
is deposited on the ground.