Question: How to calculate long-term deflection?

Answer: When checking for Code Dependent Deflections (CDD), in some situations, it is necessary to select the entire model, not just individual elements (in this case, beam B14).

If we choose only one element (beam B14), SCIA will consider only creep and long-term effects for that element, while all other elements will remain linearly elastic.

We can see that the linear (elastic) deflection in this case is 6.7 mm.

When we run the Code Dependent Deflections (CDD) check, we can see that the deflection is 8.8 mm.

From the visible deflection checks, it's impossible for the linear (elastic) deflection and long-term deflection to be almost equal.

If we look at the 3D displacement of the entire model, we can see that the displacement of beam B14 mainly comes from the slab below the beam.

Therefore, if we don't include the slab in the selection or apply any reinforcement in the slab, the deformation of this element will remain linearly elastic.

Since beam B14 is directly connected to this element, we will get almost the same displacement.