PSI - Issue 37

Dmitrijs Serdjuks et al. / Procedia Structural Integrity 37 (2022) 547–554 Dmitrijs Serdjuks/ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 3. Three variants of beam joints: (a) rigid (moment) joint; (b) pinned joint; (c) no connection.

3. Results and discussion 3.1. Results of a static experiment

The timber beam stand was statically loaded by the concentrated vertical forces system, applied as shown in Fig. 2 . Loading steps with intensity 1 kN were applied first to platform P1 and then to platform P2. The maximum intensities of the vertical loads were equal to 4.74 kN for platform P1 and 4.69 kN for platform P2. The loading stages were divided into symmetric and non-symmetric ones. The loadings of the stand were repeated for the rigid and pinned conditions of the joint between the girder and the beam. The loading and unloading regimes coincided with the stages 1-6 and 7-12, correspondingly, and are shown in Fig.4 for symmetric and antisymmetric modes. The elastic modulus of the beam’s material was estimated as 9.44 GPa. The joints stiffness was determined based on the experimentally measured angle of the joint’s rotation. The experimental values were compared with the values calculated by the FEM method using the software Axis VM Lite. Variants of the rigid (moment) and pinned joints were considered. The angle of the joint’s rotation is shown in Fig. 4 as a function of the applied vertical load . The influence of the maximum vertical displacements of the beam on the angle of the joints rotation was taken into account. The experimentally obtained value of the rigid joint rotation angle was 0.0003 radians, while for the pinned joint, the same values were 0.0025 and 0.0026 radians by FEM and experiment. The maximum rotation angle of 0.018 degrees for the rigid joint was obtained for non-symmetric loading. The maximum rotation angle for the pinned joint was 0.173 degrees in the non-symmetric loading when the vertical loads were 4.74, and 3.75 kN were applied to platforms P1 and P2. The static loading confirmed that desired conditions of the girder and the beam joints could be considered the rigid and pinned ones.

Fig. 4. The angle of the joint’s rotation as a function from the applied vertical load for loading stages (a) symmetric; (b) non-symmetric.