Vladimir Melekhov, Viktor Byzov, Aleksandr Chernykh, Shirali Mamedov


Introduction: Softwood lumber is widely used to manufacture load-bearing structures. However, the quality of round wood used to manufacture such lumber has been deteriorating lately. Round wood decreases in diameter and often has heart rot. The article looks into the possibility of manufacturing elements of load-bearing structures using beams made of round wood of small diameter that have not been previously used to manufacture structural materials for construction purposes. It is suggested to make beams of such round wood preserving the trunk structure to the maximum (heartwood beams). Due to the preservation of the annual growth ring pattern, such beams have better strength properties as compared to traditional structural lumber. Purpose of the study: The study is aimed to determine the strength properties of engineering structures’ elements made of heartwood beams sawn from round wood of small diameter. Methods: The authors tested an experimental truss made of heartwood beams by means of incremental loading until destruction. Results: The strength properties of the truss elements made of heartwood beams sawn from round wood of small diameter were determined. There is a good fit between the calculated values of stress in the truss elements and the experimental data. The structure was damaged in the panel points connecting the compression strut with the elements of the tension and compression chords. The tension elements and their joints remained undisturbed. The experimental structure has a safety factor of 2. Compared to the design load, such a value shows that the experimental truss has the required bearing capacity and is robust. The findings confirm that the strength properties of heartwood beams match the requirements for elements of load-bearing structures. The strength properties of heartwood beams make it possible to use them to manufacture load-bearing structures.


Load-bearing structures, strength properties of beams, annual growth ring pattern, experimental-truss testing.

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