This paper presents the preliminary results of strength grading of spruce structural timber based on non-destructive testing using the dynamic method - the single mode transverse damped vibration method. The main objective of this study was to evaluate the used method through the examination of correlations between the MOEdyn determined by transverse damped vibration of simply supported edgewise oriented boards, global edgewise MOEstat, and MOR. In the study the European standards dealing with the strength grading was also considered. The correlations between the investigated properties were identified to be within the range reported by other researchers. Numbers of correctly graded, upgraded and downgraded specimens were established according to the EN 14081-2 with the size matrix. 38% of specimens were assigned correctly, 60% of specimens were downgraded and only 3% of specimens were upgraded. We can evaluate the used dynamic method as an entirely reliable method but for final statistically significant conclusions a larger pattern should be considered.
COBISS.SI-ID: 1907849
A prerequisite for a sensible estimate of moisture induced stresses in timber members is an accurate prediction of the members’ moisture states during their service life. This work presents realizations of envelop curves over the possible moisture states in a timber member for some carefully chosen harmonic humidity variations. The calculations, on which the realizations were made, are based on a fully coupled transport model including a model for the influential sorption hysteresis of wood.
COBISS.SI-ID: 5458273
This paper presents some general results of national research project “Strength grading of structural sawn timber” dealing with the introduction of grading methods of softwood species into Slovenian sawmills and with the creation of extensive database containing the mechanical characteristics of sawn timber. Paper is focused on correlations between non-destructive and destructive testing of timber.
COBISS.SI-ID: 1865831