PREREQUISITES FOR TAKING INTO ACCOUNT MODIFICATIONS OF CONIFERS OF WOOD SPECIES IN CALCULATIONS OF TIMBER ELEMENTS AND STRUCTURES

Abstract

The study highlights the methodology for considering the impact of softwood modification in the design of timber structures. Although timber is a widely used building material due to its environmental friendliness, low weight, ease of processing, high longitudinal strength and cost-effectiveness, it has limitations such as moisture sensitivity, anisotropy and natural defects that limit its structural application. Modification of timber with various composite materials improves the physical and mechanical properties of timber, improves moisture resistance and increases durability. Such types of modifications change the behaviour of timber structures and their stress-strain state, which is not taken into account in current design standards, which highlights the need to update design approaches. The study focuses on structural elements, including beams, columns and cross-laminated panels, where longitudinal strength largely determines the load-bearing capacity and stiffness. Traditional design includes characteristic and design values of compressive, tensile, and flexural strengths, as well as elastic and shear moduli modified by reliability factors. This paper presents the possibility of using experimental data when taking into account the modification of coniferous wood species. In this case, experimental values are used to determine modification factors that correct the design resistance to bending, compression, tensile, and elastic moduli. Formulas are given to illustrate the application of these factors under uniaxial bending and combined loading conditions. A methodology is proposed that allows for accurate consideration of changes in mechanical behavior due to processing with composite materials, providing an accurate assessment of the strength and improved serviceability of wooden structures. The introduction of these factors into structural calculations demonstrates that modification can significantly improve the performance and service life of wooden structures. This approach lays the foundation for incorporating modified wood properties into future design standards and provides engineers with practical tools for more reliable and durable wood construction designs.