LIGHTWEIGHT PLYWOOD PANELS WITH CURVED X-SHAPED LONGITUDINAL RIBS OF RIGIDITY

The current state of the construction industry in Ukraine increases every year the percentage of buildings implemented using wood in new construction, picking up the trend of European countries, where wood is becoming the main material in the implementation of residential and public buildings. The number of floors of such timber frames already reaches 20-30 floors with load-bearing frame structures made of glued-laminated timber and CLT panels. The latter are a new innovative panel-type material that allows assembling buildings of various thicknesses easily and quickly, but their efficiency is significantly reduced for spans of more than 6 m. The proposed plywood lightweight panels or PRX panels are a solution to the problem of simple covering for increased spans of coverings and floors due to an innovative approach using bent longitudinal ribs of panels for stability of which the arrangement of transverse ribs is not required. The problem of this type of panels consists in determining the compliance of X-shaped plywood ribs based on research with the development of a simplified calculation method as a system of factors or coefficients correcting traditional algorithms for calculating similar thin-webbed structures operating in bending. In the proposed development of lightweight and simultaneously rigid panels, the main emphasis was placed on the simplicity and manufacturability of panel production, relying on modern automated production equipment. PRX panels can be used as elements of self-supporting walls. The purpose of developing innovative lightweight plywood panels was to create a new technological solution for ceilings and roofs of buildings for spans of 7-20 m. The idea of lightweight and rigid panels with X-shaped curved webs or ribs is a continuation of research on beams with such walls, where the efficiency of the curved shape of plywood walls showed certain advantages compared to classic I-beams with plywood webs. The proposed solution of the covering panels allows assembling buildings for various purposes and place insulation and some communications inside the panels quickly. To clarify the parameters of strength, deformability and determine the nature of panel failures, full-scale static tests of a full-scale sample were conducted, as well as numerical studies were performed in analytical software packages with a focus on the behavior and compliance of curved plywood walls at different stages of panel loading. Based on the experimental and numerical data obtained, a methodology was proposed that takes into account not only the geometry of the cross-section, but also its sweating of plywood walls or longitudinal ribs of PRX panels.