PSI - Issue 81

Petro Gomon et al. / Procedia Structural Integrity 81 (2026) 411–416

413

cycle.

b

а

Fig. 3. Loading scheme for beams and prisms under one-time (a) and low-cycle loading (b)

The load was applied through a spreader beam using a hydraulic jack connected to a pumping station. Beam deflections were measured with 6PAO deflectometers installed at mid-span and near the supports. The relative strains in concrete and reinforcement were recorded using strain gauges bonded along the height of the beam in the pure bending zone, as well as with MIG-1 indicators and a Hugenberger tensometer (Fig. 4).

Fig. 4. Experimental setup for beam testing

3. Results and discussion Twelve cubes and twelve prisms were tested, including six prisms under single loading and six under low-cycle loading (η =0.7). The concrete strength after low-cycle loading increased by approximately 10% compared to the strength under single loading (Table 2). When tested after exposure to low-cycle loading, the prisms demonstrated an average increase in concrete strength of approximately 10% compared to the prisms tested under monotonic loading. The test results are summarized in Table 2.

Table 2. Prismatic strength of concrete

Prism number

Load

Prismatic strength, MPa

Average prismatic strength,MPa

Prism -1 Prism -2 Prism -3 Prism -4 Prism -5 Prism -6

Single load Single load Single load Cyclic load Cyclic load Cyclic load

24.9 23.2 25.7 26.4 29.2 26.6

24.6 24.6 24.6 27.4 27.4 27.4

At the second stage, four T-beams (flange thickness 3 cm) were tested under single and cyclic loading. Failure began with the shearing-off of the flange, followed by crushing of the compressed concrete zone in the normal and inclined sections (Fig. 5). After high-level cyclic loading, the ultimate strength of the beams increased by an average of 8% , but the crack widths and deflections increased significantly.