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

250 Chapter Nine
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can be quickly assembled and disassembled, which makes it a versatile
forming system. Wing nuts or coil nuts with washers are attached
at each end to secure the tie.
The ties are completely reusable. No expendable parts are left
behind in the hardened concrete. However, taper ties will wear and
must be inspected and replaced continually when wear or damage is
noted. To facilitate removal of the taper tie from the hardened concrete,
a coating with waterproof grease should be applied to the tie
before installation. For best results in removal of the tie, the initial
bond between the taper tie and the concrete should be broken within
24 hours of concrete placement.
Standard tie lengths are available from 34 to 60 in. Thus, the ties
provide an adjustable tie length for a wide variety of wall thicknesses.
These ties are available with safe working loads varying from 7,500 to
50,000 lb, depending on the coil thread diameter. The coil thread
diameter is different at each end, due to the taper of the tie.
When ordering these ties, it is necessary to specify the quantity,
type, large and small diameter, and length. This type of tie is ideal for
walls with batters.
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Coil Loop Inserts for Bolt Anchors
Coil loops are set in concrete as anchors, and then used later to support
higher lifts of forms, to lift precast concrete members, and for
other anchorage purposes. As illustrated in Figure 9-17, several types
and sizes are available. Anchorage is obtained with coil bolts and eye
bolts whose threads engage the helical coils.
The safe working load capacity of inserts depends on the diameter
and length of the bolt, the edge distance, and the concrete strength.
Working loads range from 9,500 lb for single flared coil loop inserts to
32,000 lb for double flared coil loops, up to 48,000 lb for triple-flared coil
loop inserts.
FIGURE 9-17 Coil loop inserts for bolt anchors. (Source: Dayton Superior Corporation)
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