Applicability of the torsion test and photogrammetric approach on structural timber beams

ABSTRACT The torsion test is recommended as a standard approach to determine the shear modulus of structural-size timber and glulam beams. However, there is difficulty in measuring the rotational deformations of timber beams. A stereo camera system and photogrammetric approach are therefore proposed in this study. This study evaluates the applicability of the proposed photogrammetric approach to the torsion testing method on solid timber beams. Tests were performed comparing rotational values of specific points determined by the photogrammetric approach with those measured by traditional devices. Remarkable findings were obtained which may help to develop an outline for future research in the field of evaluating material properties of timber beams. The results also showed that the optical system not only allowed the assessment of performance and reliability of traditional sensors, but also allowed monitoring the deformation of samples at various locations by providing more information which would be unobtainable using traditional techniques.