ASSESSMENT OF STRENGTH AND STIFFNESS PROPERTIES OF RECLAIMED STRUCTURAL TIMBER OF NORWAY SPRUCE

This study reports the outcomes of strength grading of 56 test specimens of reclaimed timber members 
with cross-sectional dimensions of 48x98 mm. Timber members were assessed through both destructive and non-destructive testing methods. The examined material consisted of previously utilized Norway spruce. To determine the dynamic modulus of elasticity, an oscilloscope and a waveform generator were used to measure the propagation velocity of sound waves within the test specimen. The study also compared the results of three visual strength grading standards (INSTA 142, UNI 11119, and NS 3691-3) and destructive tests. Innovatively, the test specimens where specifically graded locally near the breaking point of destructive tests (destructive zone). This method eliminates instances where the overall rating is lower than the visual assessment of the selected section, thus avoiding an underestimation of the precision of visual strength grading methods