See Figure 17.1.

Fig. 17.1
figure 1

Diagram of the traction device

Full size image

The objective of the static and dynamic tests carried out simultaneously is to solve the first-degree equations of the type Y = Ax + B and thus to calculate A and B.

Y is the square root of the dynamic stiffness and x is the internal force of the tie rod (Fig. 17.2).

Fig. 17.2
figure 2

Square root of the stiffness function of force

Full size image

The behavior of the tie rod under tension is generally divided into three parts:

  • Initial installation phase, interference from the weight of the equipment required for testing

  • Phase in which the forces are lower than the internal tensile force of the tie rod, constant stiffness

  • Phase in which the applied force is greater than this internal force

The type of curve shown is quite common. It should be noted that exceeding the internal tensile force (blue arrow) induces a change in the equilibrium of the system. The tie rod and the ground are stressed for values that induce changes in behavior.

Tie rod 141 example.

This tie rod is located on another wall without a concrete structure nearby (Figs. 17.3 and 17.4).

Fig. 17.3
figure 3

Tie rod 141

Full size image
Fig. 17.4
figure 4

Tie rod 141

Full size image

The static test is performed simultaneous with dynamics tests. The crescent and decrescent values of force are:

  • 1,2t – 4t – 8t – 12t -and 16t

  • 12t – 8t- 4t and 1,2t (Fig. 17.5).

    Fig. 17.5
    figure 5

    Static test

    Full size image

The detachment of the support plate from the tie-head was observed under a load of 7 tons.

Detailed dynamic stiffness results are given in Appendix 7 and are summarized in the following curve (Fig. 17.6).

Fig. 17.6
figure 6

Dynamic stiffnesses T141 under different loads

Full size image

The points circled in red are characteristic of the new tie-rod load, since the tensile force exceeds the existing internal force.