*3.3. Results of the Case Study*

Figures 5 and 6 present qualitative results of flat and curved IGUs for a selected climatic load case. It should be noted that the graphical results are for the same 'summer' load case (Table 1), while quantitative results for both climatic load cases are shown in Table 3.

**Figure 5.** Out-of-plane displacements ('summer' load case) for: (**a**) flat IGU; (**b**) curved IGU. Note: Bottom view; values in m; the same scale was used for the legend on both figures (max: 7.0 mm, min: −3.0 mm).

(**a**) (**b**)

**Figure 6.** Maximum principal tensile stress ('summer' load case) for: (**a**) flat IGU; (**b**) curved IGU. Note: Bottom view; values in MPa; the same scale was used for the legend on both figures (max: 42 MPa).


**Table 3.** Results of the case study.

Figure 5 presents results for flat and cylindrically curved IGU in terms of out-of-plane displacements for the 'summer' load case. From the comparison, it can be observed that the curvature of the component pane has a significant influence on the deformation pattern. In the case of flat IGU, the panes bulge with the maximum displacement value in the centre of the pane. This behaviour is typical for rectangular, simply supported flat slabs at all edges and subjected to uniform pressure. Surprisingly, the curved IGU shows a completely different deformation behaviour. The increased pressure in the cavity due to gas expansion caused by the temperature increase and negative air pressure surrounding the IGU causes the model to 'flatten', being closer to a flat shape. This way, the short edges are lifted concerning the model's centre and achieve the maximum values at these locations.

Figure 6 shows maps of maximum principal (tensile) stress in glass, which is a critical factor in structural glazing design. For the flat IGU, the stress map follows the deformation pattern so that the location of the maximum stress is identical to the case of maximum deformation. As for deformation, the stress map is typical for a simply supported flat slab at all edges and subjected to uniform pressure. As seen in the figure, the location of the maximum stress in the curved IGU changes its location. The maximum stress for curved IGU is located at the curved edges of the component panes. This phenomenon is directly related to flattening panes, generating tension in the centre of the curved edges.

Table 3 presents the quantitative results of the case study. In terms of internal pressure, the radius of curvature of 1500 mm causes an average 477% increase in the value for the 'summer' load case, while for the 'winter' case, the increase is still significant; however, to a lower extent (218%). Regarding maximum deflection and stress, the curvature generates static values higher by, on average, 517% in curved IGU compared to the flat model.
