The objectives of the static tests are:

  • to determine the internal force at the tie rod and to calibrate the dynamic method

  • to calculate the static stiffness

  • and simultaneously perform dynamic tests to calculate the dynamic stiffness

  • to analyze the tie rod behavior with the aim of a tie rod re-tension.

The following graphical construction shows that the tensile force given by the operator is 3t higher than the one calculated graphically during unloading.

The operators who performed the static test determined the tension force of the tie rod during the loading phase, the value is 23 tons.

The graphical construction made with the elements of the unloading phase leads to a tensile force of 20 tons.

The calculation from the dynamic stiffness gives a result of 20.4 tons.

The determination of the tensile force during the increasing load phase is obtained when the metal plate lifts off the head of the tie rod.

That is, when the applied force is greater than the tension force plus the adhesion forces of the plate to the support.

When the tie rods are old, the force necessary to detach the metal plate located between the head of the tie rod and the wall is 1 to 2 tons higher than the tension force. This adhesion of the system on the wall is all the stronger that there is corrosion (Fig. 9.1).

Fig. 9.1
figure 1

Displacements (mm) as a function of tensile force in tons

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When the tie rods were re-tensioned, the following test results were analyzed:

  • Static tests

  • Dynamic tests

  • And re-tensioning operation.

The tensile strengths calculated from the static tests are generally 1.5 tons higher than the values calculated from the re-tensioning results.

Tensile strengths calculated with nondestructive tests are close to the values calculated with the prestressing results (Figs. 9.2 and 9.3).

Fig. 9.2
figure 2

Average 1,46t—Standard deviation 1,6t

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Fig. 9.3
figure 3

Source Rincent BTP—Recife

Static tests at height.

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