PSI - Issue 72

Andrii Pavluk et al. / Procedia Structural Integrity 72 (2025) 330–337

332

The experimental beam rested on wooden pads. The wooden pads, in turn, were placed on a hinged movable support and a hinged immovable support. The function of the pads was to prevent wood compression. Two concentrated loads were applied at the thirds of the span. The load distribution was ensured using a metal traverse. The load was applied using a hydraulic jack. Dial indicators ICh-10M were installed on the beam supports to record deformations. The maximum deflections of the beams in this testing setup occurred at mid-span. Therefore, deflection measurements were conducted at the mid-span of the experimental beam. The measurements were carried out using deflectometers 6PAO. The experimental setup for direct bending ensured the beam operated under pure bending conditions. The calculation scheme of the beam was a simply supported beam on two supports loaded with two concentrated forces at the thirds of the span. The beams were fabricated by gluing a package of boards. The boards were made from pine wood of grade C30 (DBN B.2.6-161 (2017), Eurocode 5 (2004)). The cross-sectional dimensions of the glued beams after assembly were 100×150 mm. The total length of the test specimen was 3000 mm, with an effective span of 2700 mm. The calculation scheme for the performance of the glued laminated beam under oblique bending was similar to that for direct bending. The load was applied to the beam at the thirds of the span using a metal traverse. The inclination angle of the beam was ensured by specially designed metal plates. These plates were installed at the load application points and at the beam supports. The deflections of the beam were recorded using 6-PAO deflectometers. The deflectometers were installed at the supports, at the load application points, and at the mid-span of the beams. Two deflectometers were placed at each specified location to measure deflections in two axes: Z-Z and Y-Y. The metal plates provided inclination angles of 10° and 25° for the glued laminated beams. To prevent the influence of torsional moments on the test beams, ties were installed at the load application points. The general view of the test setup and the beam under oblique bending conditions is shown in Fig. 2.

Fig. 2. Diagram of the experimental setup for testing beams under oblique bending

During the experimental tests, the load was applied incrementally in steps of 8 – 10% of the predicted failure load, as specified by regulatory documents (EN 380 (2008)). After each load step, readings were taken from all instruments. In total, six glued laminated beams were tested as part of the experimental studies. Two beams (GLB-1, GLB-2) were tested under direct bending conditions. Four beams (GLB-3... GLB-6) were tested under oblique bending conditions, with two beams tested at each of the two inclination angles. Failure of the experimental beams under both direct and oblique bending occurred in the tension zone of pure bending. Prior to failure, the formation of a fold in the compression zone of the beam was observed. The theoretical studies of glued laminated beams involved their modelling using the "LIRA SAPR" software package. The calculation scheme and the testing characteristics of the created model corresponded to the experimental testing setup. To simulate the behaviour of ties under oblique bending, deformations out of the beam plane were restricted at the load application points.