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Wooden-composite plate-ribbed bent panels with structural plywood and oriented strand board sheathing with breaks are considered. An overview of studies researching and improving the effectiveness of different types of panels is presented. On the basis of the theory of calculation of composite rods by A.R. Rzha- nitsyn, a mathematical model has been compiled, which makes it possible to calculate the stress-strain state of these structures, taking into account the pre- sence of breaks in the sheathing and the flexibility of the mechanical fasteners of the sheathing and ribs. An equation for finding the coordinates of the most dangerous section of wooden ribs in the presence of breaks in the sheathing, which may not match with the middle of the span, is obtained. Panels with sheathing in a compressed zone with different locations of joints, symmetrically relative to the middle of the panel span are considered. Panels without joints in the skin are considered to compare the results. The graphs of the dependence of the maximum tensile stresses in the ribs in the most dangerous section and the maximum vertical displacements from the stiffness coefficient of the shear ties and the location of the breaks in the sheathing are presented. The values of the coefficients for the engineering design of panels, taking into account the decrease in the strength and deformation characteristics of the composite section of panels with breaks in the sheathing, as compared to panels with a solid sheathing, are obtained. The conclusions and recommendations, based on the results of the investigations, which can be used in the design of wooden-composite plate-ribbed structures, are formulated.

Wood composite plate-ribbed structures working under the conditions of lateral bending in coverings and floors in buildings of various purposes are considered. The results of studies of the influence of various parameters on the stability of the upper compressed sheathing of wood composite panels with bonded joints of sheathings and ribs (type of connections, coefficient of stiffness of the bonded joints, span size, width of panels and material of anisotropic sheathing) are presented. To implement the task, the Lekhnitsky theory of calculating the stability of anisotropic plates is used, in particular, the energy method for determining the critical force for a flat anisotropic plate loaded along the edges by tangential efforts. For describing the distribution function of tangential efforts on the edges of the sheathings, the Rzhanitsyn theory of calculating composite rods is applied. As a result of numerical studies, the coefficients of longitudinal bending, which can be used in the engineering calculation of wood composite panels with mechanical and glued joints are obtained.

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