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One of the ways to strengthen and restore the bearing capacity of timber structures is the use of polymers. This paper investigates a method of reinforcing destructed wooden structures with a polymer composite. The authors present a technique for determining the physical, mechanical and technological characteristics of a composite material based on experimental studies. The article contains the results of investigations of polymer composites samples, wood samples under short-term loading, and the results of testing a polymer composite for adhesion strength in shear and bending. The results were obtained by means of a comparative analysis of the achieved strength values of healthy wood and impregnated wood with a polymer composite. According to the results of experimental studies, it was found that the strength indicators of reconstituted wood with a polymer composite when tested for compression and chipping along the fibers increase: breaking load by 22–24%, and the tensile strength by 15–17%.

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.

An algorithm of the reinforced binding elements calculation with allowance for the physical strain of concrete and reinforcement has been suggested. The three linear diagram of the concrete condition and the two linear of the tensile reinforcement that correspond to the recommended norms in Russia have been used. The task has been solved by the method of linear approximation. The finite difference method has been used at each approximation that allows to define the beam rigidity individually for each dot j =1,2 , dotted on the beam with some small spacing. A method of determining the deflection curve bending, the bending moment, the rigidity as well as the compression areas of the reinforcement suitable for any deformation of the concrete most tensile fabric from 0 to limiting value ε_b2 has been suggested. A solution for the continuous three-span beam has also been introduced.

The article is devoted to the study of the behavior of glued rods made of hot-rolled steel reinforcement and steel cables in a solid wood based on experimental tests of beam elements. The influence of eccentricity on the deformation - strength characteristics is studied with a straight-line gluing of reinforcing rods. The comparative analysis of the deformability indices of the centered and lateral gluing performed by milling with fillet groove U - shaped milling cutters was carried out. The technology of manufacturing samples, which consists of preparing wood, milling and pasting rebar into the groove, were described. The diagrams of deformation - strength characteristics of samples of various types were obtained and correlated. The conclusions were drawn about a local increase in strength in the case of using a steel cable as reinforcement and the negative effect of eccentricity on the strength of the adhesive joint during tensile tests. A visual analysis of the damage occurring during the test showed that in the manufacture of full-scale structures, glued rods should be closed with an array of wood. The conclusions were drawn about the optimal depth of milling of grooves for reinforcement, taking into account the use of adhesive compositions on epoxy resin filled with quartz sand - 1.5 depth of reinforcing bar diameter.

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 100x200 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.

For the composite structures based on wood, that include reinforced wooden structures, allowance for the influence of wood specific features as a building material allows us to evaluate its structural design as accurately as possible and ensure the required reliability and durability. Creep that causes wood deformations evolving in time can be referred to the specific properties of wood to a greater extent affecting the operation of the reinforced wooden structures. Taking into account the state of the issue to determine the effect of the long-acting loads on the stress-strain state of the reinforced glued wooden structures, the article considers the application of the theory of elastic heredity as the most applicable to assess the deformability of wooden structures in time. The conducted experimental and theoretical investigations and the reinforced glued wooden structures observations during the operational process have shown that their stress-strain state changes significantly under the load over time. Glue compositions used to connect reinforcement with wood ensure their reliable joint operation, however, as the result of the wood creep where wood is the basic material, the redistribution of forces between the reinforcement and wood occurs there on and off. At the same time normal stresses in the reinforcement and the glue joint “reinforcement - wood” increase in the calculated cross sections while they decrease in the wood, which is caused by a change (decrease) in the wood elastic modulus. Allowance for the wood creep in the design of the reinforced wooden structures will allow to determine the stress - strain state of the structure in the design more precisely. Therefore, when developing the reinforced wooden structures design standards, this factor must be taken into account.

This paper proposes a method of restoration of wooden structures by impregnating polymer composition based on epoxy resin, locally weakened destruction. Objective - research and development of technology for site remediation of wooden structures with areas of locally de-graded wood. We analyzed the causes of the destruction of wooden building structures. The pa-per sets out the methodology and the engineering based on the example of a wooden beam, the destruction of locally weakened in the core zone. Engineering calculations were confirmed by numerical experiments carried out in the program complex "Lira 9.6".

1 – Федеральное государственное бюджетное образовательное учреждение высшего профес-сионального образования «Владимирский государственный университет имени Александра Григорьевича и Николая Григорьевича Столетовых», г. Владимир, Российская Федерация В статье рассмотрены факторы тепловых потерь в стыках каркасно-панельных дере-вянных элементов, используемых преимущественно в малоэтажном строительстве. Каркас-но-панельное строительство является наиболее перспективным видом развития малоэтажной застройки в виду повышения качества и сокращения сроков возведения жилых домов. Наи-более актуальным вопросом является конструкция и качество выполняемых на строительной площадке соединений стеновых панельных элементов из деревянного каркаса. Выполнен об-зор применяемых видов стыков, рассмотрены недостатки и преимущества конструктивных и технологических решений. В работе обозначены критерии оценки эффективности конструк-тивных и технологических решений узлов соединения панельных элементов домов. Важной составляющей, обеспечивающей качество возводимого здания, продлевающей эксплуатаци-онные характеристики конструкций, а также повышающей энергосберегающие характери-стики соединения является герметичность. Существует прямая зависимость между степенью воздухопроницаемости наружной оболочки и требованиями к толщине теплоизоляции зда-ния. Повышение герметичности здания позволяет избежать в последствии излишних затрат на отопление, способствует увеличению КПД вентиляционной системы и как следствие эко-номит затраты собственника на строительство и эксплуатацию. Рассмотрен вопрос учёта те-пловых потерь путём конвективного теплообмена с использованием теории переноса массы газа в канале при наличии параллельного стенкам градиента температуры. Построены зави-симости величины тепловых потерь от величины неплотности в монтажном стыке. Вопрос совершенствования конструктивных и технологических решений стыков крупнопанельных элементов на деревянном каркасе является актуальным и требует комплексного подхода с учётом характеристик по герметичности, теплопроводности, технологичности изготовления и монтажа. Ключевые слова: деревянные стеновые панели, герметичность, теплопотери, монтаж-ный стык, перенос тепла, конвективный теплообмен.

We consider the engineering calculation of maximum stressed abutment sections of high glue-wood beam constructions, as well as strengthening these areas with glass nanoassembly. In supports of glued wood beams complex stress arises causing spalling along the fibers, crushing reproach fibers and stretching at an angle to the fibers. The article proposes a new way of strengthening these areas during the production of beams, the essence of which consists in the fact that the ends of the beam constructions are put in clip of glass in one or several layers glued to wood by epoxy resin composition including carbon nanotubes. In the calculations, wood is considered as transport materials described by rheological equations as viscosity elastic elastic body. Physical and mathematical models of fiberglass are selected. Strength of materials formulas calculated geometrical characteristics of the reduced section of strengthened near mounting area of high glued wood beams. Engineering method has shown that the existing method of calculation of wooden bent elements (on the maximum principal stresses in the middle of the span and the maximum shear stress on the support) is not applicable to high glue-wood beams. Tensile stresses at an angle to the fibers in the support areas reach peak values at a load of approximately twice lower than the load at which the maximum shear stress takes place. Engineering calculations found that supports of high beam constructions need to be strengthened. Minimal effect on enhancing by clip of glass nanoassembly by cleaving along the fibers ≥ 8 %, when crumpled across the fibers ≥ 7 %, in tension at an angle to the fibers ≥ 9 %. It was proposed to simplify the formula of geometrical characteristics of the reduced section in order to facilitate further calculations.