PSI - Issue 59

Volodymyr Romaniuk et al. / Procedia Structural Integrity 59 (2024) 479–486 Volodymyr Romanіuk et al. / Structural Integrity Procedia 00 (2019) 000 – 000

483

5

a

b

Designations:

– theoretical

– experimental

– by the relative strain of the tie (Hooke's law)

Fig. 3. Tension in: a – tie; b – spacer.

Since it is difficult to make a direct comparison of theoretical and experimental results, a comparison was made based on the areas of the stress graphs. The average deviation was for the upper flange and for the lower flange. The most significant discrepancy between theoretical and experimental stresses is observed in the area of the semi-arch near the attachment point of the spacer (see Fig. 2, characteristic section IX-IX). This discrepancy can be attributed to the increased bending stiffness of the chords in these sections due to the presence of welded gussets. The theoretical calculations consider the force transmitted from the spacer to the half-arch as a concentrated force, while in reality, it is distributed through the gussets welded to the girders along a length of 30 cm, resembling a distributed load. Theoretical stress calculations for the tie and spacer, along with a comparison to experimental results, are presented in Fig. 3 for an arch equipped with a spacer under a symmetrical load application scheme. The deformations of the top chord of the arch, both in the vertical and horizontal directions in the plane of the arch, as well as the movement in the horizontal direction of the hinged movable support, ridge node, and spacer, were of considerable interest in experimental studies. Experimental deflections were measured using deflection gauges at five cross-sections, located at distances of and 7.04 from the left support. These locations included the midpoint between support nodes, nodes of spacer attachment to the chord, and the ridge node. Figure 4 illustrates the theoretical and experimental deflection curves of the top chord of the arch, calculated and measured, respectively, for an arch with a spacer under symmetric and asymmetric load application schemes, assuming the value of the tie displacement eccentricity The results of movement in the horizontal direction of the hinged movable support C for an arch with a spacer under a symmetrical loading scheme are presented in Fig. 5. The loss of the arch's load-bearing capacity occurred due to the overall stability failure of the chord under a nodal load of from the plane of the structure between the points of application of the load, midway between the characteristic sections and (see Fig. 1). The safety margin of the structure's load-bearing capacity was . The conducted experimental studies, in addition to the results partially presented in this article, highlighted the necessity for further investigation of perforated elements when operating in a multi-span scenario, in the extreme case, according to a two-span continuous scheme, as exemplified by the half-chord of the studied arch structure. The half-chords can be considered as a two-span continuous beams, resting on designated supports (in this case, the support nodes B and C, the nodes fastening the spacer to the chord of the half-arch D, and the flanged ridge node A connecting the half-arches), attached to them by welding or mounting bolts. In calculations using an idealized