Stresses on Composite Section are Wrong

[netsonic_Sofistik]

The Composite Section is made of one type concrete, but it’s built in two stages.
Stage 1 - middle part

Stage 2 - middle part + both side parts

The structure is a cantilever beam,
at stage 1 and 2, the free end is loaded by a axial force=900kN

At Stage 1, the stress in the middle part is

Sofistik shows the correct stress

At Stage 2, the stress in the middle part is

At Stage 2, the stress in both side parts is

Sofistik shows the correct stress (4MPa) in the middle part, but the wrong stress (4MPa) in both side parts

The model files are attached, please delete the extension “.dat”, and unzip it.
3.zip.dat (1.4 KB)

[sfr]

You need to use different materials for different construction stages.
In your case you need to create C40 twice with different material numbers.

That also shows up as a warning in the calculation

[netsonic_Sofistik]

Thank you for the tip, it works

Where can I find this tip in Sofsitik manul?

[JFH]

@netsonic_Sofistik

Where can I find this tip in Sofsitik manul?

SSD / TEDDY > Help > User Manuals > All Manuals… > aqb > 2.1.3 Cross Sections