STIFNESS OF MODIFIED TIMBER BEAMS UNDER OBLIQUE BENDING CONDITIONS

Abstract

Oblique bending is one of the types of bending and occurs in wooden structures not only in an explicit form, when the direction of the load does not coincide with any of the geometric axes of the beam cross-section. This stress-strain state in wooden elements can also occur due to knots, skewing, uneven sections during manufacture, etc. The aim of the work is to study the stiffness of wooden beams modified with different solutions under conditions of oblique bending at different angles of inclination. Studies of wooden structures in bending show that the loss of load-bearing capacity of beams after the second group of limit states occurs much earlier than after the first group.

The modeling and analysis of modified wooden beams subjected to oblique bending were performed using the Lira software suite. Beam modification involved surface treatment with various solutions. The first series of beams was treated with Imersol-aqua solution, while the second series accounted for the altered physico-mechanical properties of wood following treatment with the polymer composite "Silor." The third series consisted of untreated wooden beams, serving as the control group.

Deflection responses of the treated beams were compared to those of the untreated series. Beam calculations were conducted for inclination angles ranging from 1° to 25°. Deformation behavior was analyzed at different load levels, from 0.2F_max to 0.8F_max. It was observed that increasing the inclination angle leads to higher beam deformations, with a more pronounced effect on deflections in the y–y plane (out-of-plane relative to the beam).

The stiffness of beams treated with Imersol-aqua increased by up to 12,2%, while beams treated with "Silor" exhibited an increase of up to 17,1% compared to untreated wooden beams. These results indicate that surface modification can significantly enhance the structural performance of wooden beams under oblique bending conditions.