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![]() These works are licensed under a Creative Commons Attribution 4.0 International License. D.K. Arleninov, D.A. Bekker Complete text of the article:Download article (pdf, 0.5MB )UDС691.11DOI:10.17238/issn0536-1036.2015.6.128AbstractThe stress level in the structure largely influences on the rate of wood creep under the steady load. Previously deformation properties were investigated in a lesser extent, in the stage of nonlinear creep. Therefore, there are no experimental data of long-term tests at low stress levels, allowing us to obtain the “stress – strain” dependence. The purpose of the experimental studies is to obtain the quantitative estimates of wood creep, expressed in total (elastic and residual) strain at the design stress levels of various rates. Long-term tests of four spruce samples, sawn from one board, were carried out in the mode of “bending” at different stress levels of 2 uA … 13 uA. The tests were carried out in a dry and warm room under the stable thermal and moist conditions. Samples moisture content during the tests was 6 %. The test validity, reduced to 12 % of moisture by the known formu-las, was estimated by comparing the calculated values of short-term and long-term modulus of elasticity and the standard values. The study results confirmed the prerequisite about the impact of the stress level on the value and period of the creep process. At low levels of nor-mal stress the creep attenuation in the midspan occurred within the first month. At stresses close to the calculated resistance the creep attenuation in the samples occurred in six months. During the seventh month the increase of deflection was not observed. According to the measurements of deflections at the test period the actual values of total strains were cal-culated. These values were used for “total strain – hold time” plotting for each sample. These graphs were the basis of the presented in the paper dependence “stress – total strain”, which can be used to determine the modulus of deformation. It is concluded, that for the construction of reliable empirical dependence and further approximation it is necessary to continue the research by increasing the number of samples and the range of stress levels.AuthorsD.K. Arleninov, Doctor of Engineering Sciences, Professor D.A. Bekker, Head of LaboratoryAffiliationMoscow State University of Civil Engineering, 26, Yaroslavskoye Shosse, Moscow, 129337, Russian Federation; e-mail: dkarleninov@mail.ru; vonbeck@mail.ruKeywordswood creep, steady load, modulus of elasticity, strain.References1. Baltrushaytis A.V. Prochnost' i stoykost' derevyannykh kleenykh konstruktsiy s razlichnoy tolshchinoy sloev: dis. kand. tekhn. nauk [Strength and Resistance of Wood-en Glued Structures with Different Thickness of Layers: Cand. Eng. Sci. Diss.]. Moscow, 1986. 182 p. 2. Belyankin F.P. Dlitel'noe soprotivlenie drevesiny [Continuous Resistance of Wood]. Moscow, 1934. 345 p. 3. Zubarev G.N. Razrabotka i issledovaniya kleenykh konstruktsiy dlya pokrytiy promyshlennykh zdaniy: dis. … kand. tekhn. nauk [Development and Research of Glued Structures for Industrial Buildings Coating: Cand. Eng. Sci. Diss.]. Moscow, 1954. 202 p. 4. Ivanov Yu.M. K metodike opredeleniya deformatsiy derevyannykh konstruktsiy v pokrytiyakh zdaniy [To the Technique of Strain Definition of Wooden Structures in the Building Covering]. Izvestiya VUZov. Stroitel'stvo [News of Higher Educational Institu-tions. Construction], 1990, no. 6, pp. 107–109. 5. Ivanov Yu.M. O predel'nykh sostoyaniyakh derevyannykh elementov, soedineniy i konstruktsiy [On Limit States of Wooden Elements, Compounds and Constructions]. Mos-cow, 1947. 280 p. 6. Ivanov A.M. Prikladnaya teoriya polzuchesti drevesiny [Applied Theory of Wood Creep]. Sbornik nauchnykh trudov Voronezhskogo ISI [Proc. Civil Engineering Institute of Voronezh], 1957, no. 6. 87 p. 7. Klimenko V.Z. Fenomenologicheskiy podkhod k raschetu szhato-izgibaemykh derevyannykh elementov [Phenomenological Approach to the Calculation of Beam Wooden Column]. Stroitel'naya mekhanika i raschet sooruzheniy, 2011, no. 1, pp. 7–11. 8. Lin'kov N.V. Nesushchaya sposobnost' i deformativnost' soedineniy derevyannykh konstruktsiy kompozitsionnym materialom na osnove m atritsy i steklotkani: dis. … kand. tekhn. nauk [Load Bearing Capacity and Deformability of Joints of Wooden Structures by Composite Materials on the Basis of Matrix and Fiberglass: Cand. Eng. Sci. Diss.]. Moscow, 2010. 154 p. 9. Pyatikrestovskiy K.P. K voprosu o vybore moduley uprugosti pri raschete derevyannykh konstruktsiy na prochnost', ustoychivost' i po deformatsiyam [On the Selec-tion of the Elastic Moduli in the Calculation of Timber Structures for Strength, Stability and Deformation]. Stroitel'naya mekhanika i raschet sooruzheniy, 2012, no. 6, pp. 73–79. 10. Roshchina S.I. Prochnost' i deformativnost' kleenykh armirovannykh konstruktsiy pri dlitel'nom deystvii nagruzki: dis. … dokt. tekhn. nauk [Strength and Deformability of Glued Reinforced Structures under Long-Term Loads: Doc. Eng. Sci. Diss.]. Vladimir, 2009. 259 p. 11. Tsepaev V.A. Otsenka modulya uprugosti drevesiny konstruktsiy [Evaluation of the Modulus of Elasticity of Wooden Structures]. Zhilishchnoe stroitel'stvo [Housing Construction], 2003, no. 2, pp. 11–13. Received on May 22, 2015Effects of Stress Level on Wood Creep under Bending |
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