Method of assessment of stress-strain state of timber-reinforced concrete structure with complex cross section

The application of timber structures is often limited by the size of the lumber, insufficient load-bearing capacity and rigidity of the elements. To overcome these limitations hybrid designs which rationally use materials with different characteristics are used in modern construction. The existing techniques do not take into account the peculiarities of the diagrams of deformation of structural materials (wood and reinforced concrete). The purpose of the article is to improve of methods for calculating wood-reinforced concrete structures, taking into account the stress-strain relationships of materials and the degree of joint work. Conclusion. A numerical-analytical method is proposed for the assessment of the stress-strain state of a timber-reinforced concrete structure with complex section, taking into account the deformation diagrams of materials and joints, as well as the degree of joint work. A considered structure consists of two components (reinforced concrete slab and timber beam) connected by shear elements (pins, bolts, screws, nails). It is supposed that the Bernoulli hypothesis is valid for the considered element; the deformations are linearly distributed along the height of the cross section, while a gap arises along the line between the components of the structure due to mutual displacement; structural components under load have equal deflections and curvatures of the longitudinal axes, and the connecting elements are uniformly spaced along of the structure. Determination of the internal deformations and stresses in a section of a structure is based on the condition of equilibrium of the external and internal forces in the section. The solution of the equations for "absolutely" joint work is performed, and the coefficient of joint work is introduced to take into account the redistribution of forces in the section due to the ductility of the joints. The obtained values of longitudinal deformations and curvatures are used to calculate the deformations of concrete and timber elements. Normal stresses are determined using the deformation diagrams of materials, then the strength checks are performed in accordance with the current regulatory documents.