Prediction of the mechanical properties of timber members in existing structures using the dynamic modulus of elasticity and visual grading parameters

The modulus of elasticity and bending strength of 45 structural Salzmann pine timber pieces with nominal dimensions of 150x200x5400 mm3 from an existing 18th century structure were estimated by semi-destructive density estimation probing method (drilling chips extraction) and acoustic wave velocity (stress and ultrasound wave). Bending strength, modulus of elasticity and density were obtained according to the EN 408 European standard, and visual grading singularities were recorded. Visual grading methods are highly ineffective for existing timber structures. Sample mechanical properties show a typical profile of material from existing structures, and this was compared with the results of similar works. MOE and MOR predictive models were proposed with determination coefficients r2 of 66-68% and 51-52%, respectively, using dynamic MOE, relative edge knot diameter and slope of grain as independent variables. MOR prediction improved when these grading parameters were included.

Automated summary

In this study, the modulus of elasticity and bending strength of structural Salzmann pine timber from an 18th century structure were estimated using semi-destructive density estimation and acoustic wave velocity methods. The results were compared, and predictive models for modulus of elasticity and bending strength were proposed, with an improvement in the prediction of bending strength when grading parameters were included.