Answer:
The deformations for the serviceability limit state design in STEEL EC3 are usually related to the shifted ends of members or sets of members. This is useful, because you want to perform the design for the local component.
In the case of a result combination from load cases with the form LC1/s + LC11/s or up to LC31, the reference to the deformed system may lead to implausible results. The reason for this is that the values of the shifted member ends can originate from independent load situations, and thus, it is not possible to determine the correct rise value.
The image shows the enveloping deformation of an RC from the type (LC1/s + LC11/s or up to LC31). The deformed member ends always originate from different load cases. Here, this was replicated with COs for comparison. It is not reasonable to evaluate the rise determined in the center of the member.
We recommend working with load combinations in such cases.
