Answer:
It is necessary to consider the effect of the stress concentration at the notch for the ultimate limit state design. According to EN 1995‑1‑1, 6.5.1, this is ensured by the reduction factor kv. The calculation of kv is defined in EN 1995‑1‑1 in equations 6.61 to 6.63. Further specifications for the reduction factor can also be found in the National Annexes.
In our example, the reduction factor kv is determined as expected.
In the other structural system, the reduction factor kv is determined as 1.222.
In the example, this is due to the fact that a supporting moment is created for the structural system and for the load on the supports.
Therefore, the effect of the stress concentration may be neglected at this point, according to EN 1995‑1‑1, 6.5.1 (2). "The influence of the stress concentration may be neglected in the following cases: […] Bending with compression stresses in the notch, see Figure 6.10b."
In our example, the reduction factor can even exceed 1.0 according to the specifications in DIN EN 1995‑1‑1/NA, Formula (NA.60).