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4.2 Suspension Method
1) Wrap a layer of self-vulcanizing rubber tape about three cm from each gage end, as shown in
Figure 8. (This is not necessary for Model 4210 gages.) The layers of rubber serve as a shock
absorber, dampening any vibration of the suspension system. Without the rubber layers the
resonant frequency of the tie wires may interfere with the resonant frequency of the
gage. This can result in unstable readings or no readings at all! This effect disappears
once the concrete has been placed. For an alternative method, which avoids this potential
problem, see Section 4.3.
2) Select a length of soft iron tie wire, similar to the kind that is normally used for tying rebar
cages together. Wrap the wire around the rubber strips two times.
3) Twist two loops in the wire, one on either side of the gage, at a distance of about three cm
from the gage body. Repeat this process at the other end of the gage.
4) Position the gage between the rebar and twist the wire ends twice around the rebar, then
around itself.
5) Tighten the wire and orient the gage by twisting on the loops between the gage and the rebar.
6) Tie the instrument cable off to one of the rebar using nylon cable ties.
Figure 8 - Suspending Model 4200/4200L/4 200HT Strain Gages Between Rebar
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