Verification of the photogrammetric approach on the torsion test method for timber beams

Abstract

The photogrammetric approach was proposed in this study to evaluate torsional behaviour of glulam timber beams during the torsion test. The main objectives were to investigate the applicability of the photogrammetric approach and to monitor more details of angles of twist of glulam timber beams. Experiments were conducted and the twists on long and short sides of the cross section were measured using the photogrammetric approach and inclinometer sensors, which were used to validate the accuracy. The test results showed that the optical system allowed monitoring the rotations of the samples at different locations which would not be possible to obtain using the traditional techniques. The results also showed that there is a non-linearity from the measurement of the shear displacements along the long side of the cross-section. However, the average rotation shows clear agreements with the inclinometer readings.

Experimental Investigation of Curved and Straight Laminated Bamboo-Concrete Beams with New Calibration Method for Interface Slip

“…An increasing number of TCC structures have been applied in the refurbishment of existing timber oors, construction of new oors, or as a deck for timber bridges all around the world [2]. The growing demands from the industry have also attracted increasing research interest in this area and its relevant supporting technologies in recent years [3][4][5][6][7][8][9][10][11][12]. However, growing concerns associated with deforestation's environmental and ecological impact highlight the need for alternatives to traditional wood materials.…”

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

“…When performing torsion tests, one must consider how to effectively measure and extract the torque-rotation relationship – unfortunately, it is not feasible to use the torsion machines end rotation data alone to determine the beams mechanical properties such as the shear modulus (Gharavi et al, 2018; Mohamed et al, 2021a, 2021b; Zhang et al, 2012). Measuring the required torsional displacements can be performed with fair accuracy using traditional contact-based devices such as inclinometers or linear variable differential transformers (LVDTs) (Mohamed et al, 2021a, 2021b, 2021c; Mohamed et al, 2015; Zhang, 2012), although these still come with limitations. Inclinometers are limited to one device per data point, the measurement accuracy is limited by the base size of the sensor and can only measure in x and y dimensions.…”

“…Monitoring tools using photogrammetry and image processing have been used in timber to measure mechanical properties, 3D displacements, or deformations at various points of the same specimen, as proposed in various experiments (Gharavi et al, 2017; Gharavi and Zhang, 2018; Gharavi et al, 2018; Mohamed et al, 2021a, 2021b, 2021c; Mohamed et al, 2015; Zhang, 2011; Zhang, 2012; Zhang et al, 2012; Choi et al, 1991; Dahl and Malo 2009a, 2009b; Franke et al, 2007; Franke et al, 2007; Garcia and Orteu, 2001; Maas and Hampel, 2006). In contrast to traditional techniques, the binocular stereo vision approach is a non-contact measurement technique that can be used to extract reliable measurements of physical objects from stereo images.…”