Wooden multi-span beams with steel reinforcement were studied experimentally on a stationary stand using an eight-point loading scheme that simulated a load uniformly distributed over the beam span. The studies were carried out on beams with a span of 4.8 m with a cross-sectional area of 40 mm × 80 mm, reinforced in the stretched zones of the cross-section with rods made of hot-rolled steel reinforcement of A400 class. The rational zones for the location of reinforcements in the tensioned and compressed zones of the beams were determined. The rational placements of reinforcement in the support and span zones was based on the numerical simulation of the volumetric stress state calculated using the finite element method. It was experimentally confirmed that the failure of wood composite beams had a plastic nature and occurred only along normal sections. This excluded the possibility of brittle fracture from shear stresses and ensured the operational reliability of structures as a whole. It was shown that the proposed rational reinforcement of wooden beams increased their bearing capacity by 175% and reduced bearing deformability by 85%. The results obtained indicated high efficiency of the application of the developed method of reinforcement in beams of roofs and floors of buildings.

Peculiar features of engineering and numerical calculations of wooden beams reinforced with polymeric composites with the local modification of the wood compression area under an insufficient volume of the initial data have been considered in this article. A technique for determining the physical and mechanical properties of materials and a stress-deformation diagram based on experimental investigation has been described. The enlarged algorithm of engineering calculation on the enumerated geometrical characteristics and numerical calculation by the consecutive loading technique and with correcting of the tangent modulus of elasticity at each step instantiated in PC Lira 10.6 has been presented. Analysis of the stress-strain state of wood-composite beams with local modification of wood has been made. Comparative analysis of engineering and numerical calculations has been performed within the limits of the calculated load. Conclusions on the results of theoretical investigations of the proposed beam construction have been formulated and compared with the existing investigations in the field of reinforcement of beam constructions with polymeric composites.

The article offered the option of reconstruction of a warehouse of wooden structures using modern derivatising materials. The reconstruction involves the insertion of additional overlap of the modified beams. The article deals not only with the calculation of a new type of beams, but also presents the developed technology of their production, tested on test samples. During the tests it was found that the destruction of the beams reinforced with fiberglass with the inclusion of carbon nanotubes in the composition of the adhesive composition is plastic in nature in contrast to the whole-wood beams. When brought to the limit state of the wood rupture of fiberglass impregnated with modified resin does not occur. The use of a new type of beams symmetrically reinforced in the edge zones of beams will reduce the consumption of wood and increase the height of the operated premises in comparison with conventional glued beams.