Structural solutions of wood-concrete floors using shear-resistant joints

Currently, various composite structures made of wood, steel and concrete are used in construction. Some studies are aimed at developing the direction of wood-concrete slab-ribbed structures. Analyzing the methods of joining wood-concrete structures, it was found that the stiffness at the “edge-slab” border has a significant effect on the stress-strain state of the whole structure, and rigid joints allow using the positive properties of concrete and wood materials more rationally, taking into account structural, rheological and physical properties. To increase the shear resistance at the border of joining, a new combined joint based on the unilateral gear plate “Bulldog” and a screw nog is proposed. A numerical model has been made to calculate the joint deformation due to the action of a single shear force, which is based on the law of deformation of linearly elastic materials and the Winkler model. It describes the deformation of a nog lying on an elastically deformable base. Empirical formulae were used to take into account the nonlinearity of deformations during the long-term impact of force on the joint in conjunction with the anisotropy of wood. The dependence curves of the joint stiffness coefficient on the diameter of nog, gear plate and the restraint value of nog in the wood are constructed for dowel and combined joints. It was shown that reinforcement of the joints (up to 6-7 times) could be achieved by increasing the diameter of the nog, and combined compounds based on a gear plate allows to increase this indicator by 2…4 times. The use of screws is recommended as cross-links, the presence of concrete in the head and thread in the wood will reduce the negative effect of warping of wood during shrinkage on the operation of the proposed compounds.