Question:
I applied a unit load of 1 kN/m² to the top slab of a 3D model consisting of three identical floors to determine the spring stiffness of the supports from axial forces and deformations of the columns for 2D modeling of the slabs. Despite deactivating the self-weight of the structure, the column axial forces are redistributed story by story. Is it possible to deactivate this effect?
Answer:
This effect is most likely caused by the bending, torsional, and shear stiffness of the slabs and can be avoided by modifying the stiffnesses.
To modify the stiffnesses, open the "Modify Stiffness" tab in the "Edit Surface" dialog box; see the image.