The purpose of this work is to study the strength of wooden beam structures with local modification of wood in the compressed zone. To achieve this goal, the physical and mechanical characteristics of modified wood were determined using modifiers based on ed-20 epoxy-diane resin, urea-formaldehyde resin, and dimethacrylic polyester. The best physical and mechanical characteristics were obtained for samples using dimethacrylic polyester: the ultimate strength was 84 MPa, the elastic modulus was 21 GPa. The increase in strength compared to solid wood was 46%, and the increase in the modulus of elasticity was 54%. Tests of beam structures with a span of 4.5 m and a cross section of 100×200 mm with local modification of wood in the compressed zone with a polymer composition based on dimethacrylic polyester were carried out. The increase in the strength of beams with local modification in the compressed zone compared to solid wood was 11% within the design loads, and the increase in stiffness by 18%. The “load-strain” relationships are constructed based on the test results. It is established that the greatest effect can be achieved when using external reinforcement systems together in a stretched zone by reducing the influence of defects and defects in beam structures and local modification of the extremely stressed compressed zone.
The development of wooden structures tends to create systems, types, elements and types of connection that would allow you to save wood while increasing the load-bearing capacity and best take into account its physical and mechanical features. One of the priority directions is the creation of lightweight composite bent structures based on wood. The scientific novelty of the article consists in the study of multi-span continuous composite beams, the use of which is possible both in new construction and reconstruction. Composite multi-span wood-glued beams with the proposed reinforcement scheme are an experimental design and to date, their work is poorly studied. The essence of the proposed design is to strengthen the lower zones in the spans of the beam and the upper zones of the beam at the location of the support with fiberglass on an epoxy oligomer. To perform the calculations, we set a model of a beam with three spans of 1.5 m. the Load is assumed to be evenly distributed along the entire length of the beam. A comparison of the structure to assess its rationality was carried out with an unreinforced glued beam with the same design scheme. The study found that, in contrast to wooden beams, the strength of composite beams with rational reinforcement of stretched zones increases by 24-27 %, and the deformability decreases by 8-13 %. From the point of view of the work, it is proposed to use the method of vacuum infusion, which is proven, which has a positive effect on technical and economic indicators.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.