PSI - Issue 74

Petr Miarka et al. / Procedia Structural Integrity 74 (2025) 50–55 Petr Miarka / Struc tural Integrity Procedia 00 (2025) 000 – 000

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Fig. 4: Obtained damage parameter ω for low-cycle fatigue tests.

Fig. 4 shows the progressive damage ω evolution during low-cycle loading indicating non-linear behaviour after reaching CMOD of approx. 0.05 mm which corresponds to P max at peak load from fracture static tests as presented in Fig. 3(a). Similar results were obtained by Baktheer (2024) 3.2. High -cycle f atigue tests Material’s fatigue resistance presented by measured S-N curve covers wide range of the data from low-cycle to high-cycle fatigue Fig. 5(a). The following coefficients were obtained: the slope B of -0.017, which could be considered as standard for HPC concrete as the study Miarka et. al. (2022) measured similar value of -0.017. and coefficient A corresponding to static strength of 5.574 MPa.

(a)

(b)

Fig. 5. High-cycle fatigue results – (a) S-N curve and (b) – Paris’ law.

Obtained values are with the expected range, for normal type of concrete with compressive strength f c < 60 MPa coefficient B is ranging from -0.03 to -0.04 see e.g. Šimonová (2021) and Miarka (2025) showing more rapid mechanical degradation due to cyclic load. Experimental results from the S–N curve indicate that a reduction of around 30% in static strength is necessary to attain the fatigue strength limit at 2 × 10 6 load cycles. The obtain Paris’s law constants are slope m with value of 15.036 and constant C with value of -8.067. The parameters characterizing fatigue crack growth rate in concrete are again in previously observed range see Bažant and Schell (1993).