Adapt the strength of steel materials
The Eurocode specifies different yield and ultimate strengths for each steel material, depending on the thickness of the plates.
This is why for each steel material you will find the option thickness range, which opens up a dialog that defines the yield and ultimate strength for a range of plate thickness.
These are the values that will be used in the steel code check and not the values shown just above this thickness range.
Therefore if you wish to adapt the yield or ultimate strength of a steel material in SCIA Engineer, it must be done inside the thickness range dialog.
Note: since SCIA Engineer 19.1 it is not possible anymore to change the values for ultimate strength and yield strength in the materials window, so you are obliged to change it in the thickness range window.