PSI - Issue 59

Svyatoslav Gomon et al. / Procedia Structural Integrity 59 (2024) 559–565 Svyatoslav Gomon et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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- stage II (Fig. 3b): the element operates without folds in the compressed zone under stresses ; - stage III (Fig. 3c): folds develop in the compressed zone of the wooden element, and wood works under stresses in both the compressed and tension zones ; - stage IV (Fig. 3d): the stage of destruction of the wooden element under stresses in the tension zone . The “calculated cross - section” with a fold in the compressed zone of the wooden element allows the application of known laws of deformation distribution along the height in both the compressed and tension zones, as the apparatus of infinitesimally small quantities can be utilized. This apparatus can be used under the condition of the continuity of the function in the vicinity of the considered cross-section point. The use of this apparatus in the mechanics of a solid body is justified by the assumption of material continuity and homogeneity. These conditions are practically fulfilled in the cross-section with a fold in the compressed zone of the wooden element. Therefore, the “calculated cross - section” represents a model that reflects the regularities of def ormation and destruction of the wooden element. , and in the tension zone -

Fig. 3. Stages of the stress-strain state of the calculated normal section of the bending elements: ( a) Stage І; ( b) Stage ІІ; ( c) Stage ІІІ; (d) Stage ІV . An approach to determine the strength and deflections of elements made of solid or glued wood, operating under transverse straight or oblique bending, has been adopted. For constructing the deformation model to calculate wooden structures, the initial data on the shape of deformation and stress diagrams and the relationship between deformations and stresses are obtained theoretically. The acceptance of the concept of the “design cross - section” allows the use of an adopted law of deformation distribution along the height of the cross-section and a layered connection between deformations and stresses acting in the compressed and tensile zones of the section.