PSI - Issue 81

Mykola Polishchuk et al. / Procedia Structural Integrity 81 (2026) 282–286

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(2020); Janiak et al. (2023); Green and Kretschmann (1992); Pavluk et al. (2024); Bojok and Vintoniv (1992); Roshchuk et al. (2024)).

Nomenclature σ с

stress;

relative strain;

u c Е ’

secant modulus of deformation;

η

load level. humidity

W

The aim of this study is to conduct experimental investigations of pine wood specimens under single short-term axial compression along the grain with varying water saturation periods and to determine changes in the modulus of elasticity and secant modulus of deformation under such operating conditions. 2. Methods of experimental research The characteristics of wood largely depend on its moisture content. Moisture is determined as the percentage ratio of the mass of water to the mass of dry wood and varies according to the ambient humidity. For the study, four series of solid pine wood prisms with dimensions of 45 × 45 × 250 mm were used (Fig. 1). The specimens were produced from a single long beam with a thickness of 25 mm in accordance with current standards (DSTU 3129:2015; DSTU EN 518-2003; DSTU EN 336-2003; DSTU 4922:2008; DBN B.2.6-161:2017; Eurocode 5:2004). The pine wood was of grade I. All faces of the prisms were planed after fabrication. Specimens with significant visible defects were rejected. The width of the annual rings did not exceed 4 mm, and their orientation was parallel to one pair of lateral faces and perpendicular to the other. Each series differed by the duration of water exposure and contained five prism specimens.

Fig. 1. Dimensions of the investigated pine wood specimens

Thus, the series were as follows: Series I (P-0) – prisms at 12% moisture content; Series II (P-0.5) – prisms immersed in water for 30 minutes;

Series III (P-1) – immersed for 1 hour; Series IV (P-24) – immersed for 24 hours; Series V (P-120) – immersed for 120 hours. After impregnation of the samples, their moisture content was also measured. The scope of the experimental study is presented in Table 1.