| Abstract [eng] |
This work consists of three main parts – literature review, testing techniques, procedures and experimental results. In the first part of this work, publications related to non-destructive evaluation of timber are reviewed. Research based on glued laminated timber and other laminating methods, including stress laminated timber is also discussed. The purpose of this work is to determine relationships between stiffness and strength of laminated beam elements. Tests were conducted with samples of Scots pine (Pinus sylvestris). Elements are comparatively small-sized and can be divided into three length groups: those of 1010mm, 950mm and 750mm. Primary characteristics, such as dimensions, density and moisture content were determined. Natural frequency and modulus of elasticity was defined by a hand-held device “Timber Grader MTG”. Each element was assigned to a certain strength class varying from Reject (non-structural timber) to C40. Parameters of more than 140 samples were determined. In accordance with EN 408 standard, the four point bending test was carried out, verifying non-destructive evaluation. Elements for further tests were selected. Some dimensional adjustments and redetermination of characteristics were made. Then a test to determine the influence of lamella position to the elastic-plastic properties of the beam was carried out. Sample length of 750mm was used for this test. Later a quantity related experiment was conducted. In this test elements with length of 950mm and 1010mm were used. A total of 24 lamella were glued together to make sample beams. Their characteristics, including natural frequency and modulus of elasticity were determined. It has been noticed, that the position of lamella does not have any significant effect on the elastic-plastic properties of the beam. Also, with the increasing number of elements in a beam, the correlation between volume and modulus of elasticity increases. |
