Plane Strain when Bending Round Cylindrical Anisotropic Heterogeneous Orthotropic Timber

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UDС

694.093.6:413.82

DOI:

Abstract

It is presented the output from the calculation formulas of strength and deformation indicators by bending of constructing plank timber with ring macrostructure considering the heterogeneity of wood within the annual rings. Wood in the trunk of a growing tree is a circular structure of the annual rings. In each annual ring are autumn-wood and summer-wood. Autumn-wood is denser, heavier and harder than summer-wood. From the amount of the autumn-wood depend color, density and durability of wood. The ring structure of wood contributes to the enhancement of its strength. In constructing plank timber, from which elements of building bearing structure are made, is advisably to retain the maximum of whole annual rings. It is possible when using of constructing plank timber with large sections with the presence of the boon. The purpose of the work is the solution of the problem of calculating the strength characteristics of constructing plank timber with wood macrostructure of which represents a system of coaxially beaded thin-walled shells to each other, simulated the annual rings of wood. To solve this problem is obtained the method of calculation of strength and deformation indicators of logs with an annular structure. By the carrying out of the researches of wood strength properties it is often considered as a homogeneous material, which does not take into account properties of autumn-wood and summer-wood annual rings. Actually wood is non-uniform material and heterogeneity of its apparent in variability of the properties in the radial direction, which is its natural feature. Frequency of changes in the properties based on the autumn-wood and summer-wood of annual rings is observed. To simplify the task was adopted the same width of both the annual ring zones. On the basis of these provisions were developed methods for calculating the strength and deformation indicators of logs with an annular structure. The periodicity of changing properties based on the autumn-wood and summer-wood of annual rings is considered. The solution will enable studies of stressed state of the building structure elements with annular structure by bending considering the heterogeneity of wood within the annual rings.

Authors

V.I. Melekhov1, Doctor of Engineering, Professor, V.N. Glukhikh2, Doctor of Engineering, Professor, V.E. Byzov3, Candidate of Engineering, Associate Professor 1Northen (Arctic) Federal University named after M.V. Lomonosov, 2Saint Petersburg State Forest Technical University named after S.M. Kirov, 3Saint-Petersburg State University of Architecture and Civil Engineering,  1Naberezhnaya Severnoy Dviny, 17, Arkhangelsk, 163002, Russia, е-mail: lti@narfu.ru 2Institutskiy per, 5, Saint Petersburg, 194021, Russia, е-mail: public@ftacademy.ru 32-d Krasnoarmeiskaya, 4, Saint Peterburg, 190005, Russia, е-mail: mapana@inbox.ru

Affiliation

1Northen (Arctic) Federal University named after M.V. Lomonosov, 2Saint Petersburg State Forest Technical University named after S.M. Kirov, 3Saint-Petersburg State University of Architecture and Civil Engineering,

Keywords

round anisotropic cylindrical log, annual ring, strength and deformability indicators.