Slabs with stress-aligned ribs compared to slabs with orthogonal ribs

For my master thesis I am testing if slabs with stress-aligned ribs are more structurally efficient (i.e., are stronger while using less material) than traditional slabs with straight, orthogonal ribs:

These variants behave as one-way slabs with fixed supports in their shortest edges. When I compared their structural behavior I noticed the following:

  • The variant with stress-aligned ribs has more displacement and less intense colors (for both utilization and principal stresses) than the variant with orthogonal, straight ribs. This means that orthogonal ribs are more efficient than stress-aligned ribs, contrary to what Pier Luigi Nervi wanted to achieve in projects such as the Gatti Wool Factory?
  • In case these results are wrong and stress-aligned ribs should be more efficient, what can I do so that they have less displacement than the orthogonal ribs?
  • Although the variant with stress-aligned ribs has more displacement, its ribs have less bending than the variant with orthogonal ribs; i.e., the slab with orthogonal ribs has sagging curvature, while the slab with stress-aligned ribs remains flat and only “breaks” or “folds” near the contraflexure regions (the regions were sagging becomes hogging). This means that the “stress-aligned ribs” approach actually works, and it could be having more displacement due to the elasticity of the contraflexure region of the slab?

Here are the files:
Master Thesis.3dm (252.9 KB)
Master Thesis.gh (230.6 KB)

Thanks for your help!

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