PSI - Issue 72

Andrii Pavluk et al. / Procedia Structural Integrity 72 (2025) 330–337

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Fig. 8. Experimental and theoretical deflections of glued beams under oblique bending (inclination angle 25°)

The load-bearing capacity according to the second group of limit states was determined from the graphs at the point of reaching the ultimate deflection. According to current regulatory documents (DBN B.2.6-161:2017 (2017)), the maximum allowable deflection of beams is 1/150l . In our case, the maximum allowable deflection of the beams is: = 15 0 = 2 1 7 5 0 0 0 =18мм , (2) where l is span of the beam. As seen from the graphs, the growth of theoretical deflection values followed an almost directly proportional relationship. The experimental values at an inclination angle of 10° were closer to the theoretical values compared to those at an inclination angle of 25°. The load-bearing capacity of beams GLB-1...GLB-6 according to the second group of limit states is presented in Table 1.

Table 1. Comparison of experimental deflections with deflections determined in the "LIRA SAPR" software Nature of behaviour Ultimate deflection, mm Experimental, M 1 , kNm Theoretical (Lira Sapr) M 2 , kNm | 1 − 2 |, % Direct bending 18 13.60 7.44 45.3 Oblique bending (10 0 ) 18 7.74 6.60 14.0 Oblique bending (10 0 ) 18 10.58 6.49 39.0

The study of glued beams under direct and oblique bending at inclination angles of 10° and 25° showed that the experimental ultimate moments were greater than the corresponding values determined theoretically. Considering this, it can be concluded that theoretical calculations in the "LIRA SAPR" software provide a safety margin for beam calculations according to the second group of limit states, as the theoretical calculations do not fully account for the physical and mechanical properties of wood and the specific behaviour of beams under oblique and direct bending conditions. 4. Conclusions As a result of the experimental and theoretical studies, new data were obtained on the load-bearing capacity and deformability of glued beams under oblique and direct bending conditions. Based on the results, the following conclusions can be drawn: 1. the ultimate experimental deflections of glued beams at an inclination angle of 10° occur at an average moment value of 7.74 kNm, and at an inclination angle of 25° at 10.58 kNm;