Question
During the construction phase, should the boundary conditions of the Elastic link be set to Deformed or Original?
During the construction phase modeling, I created a concrete slab on top of a steel box.
When creating the slab, I used the Deformed condition for the Elastic Link, but during the slab creation phase, the shape of the slab is positioned below the top of the steel box, not on it.
If I choose the Original condition, the shape seems to come out normally, but the reaction and member force results seem more appropriate with the Deformed condition.
I would like to know why the shape is correct with Original and why it comes out strangely with Deformed.
Answer
The displacement shape displayed on the screen is an exaggerated shape, which is the actual displacement multiplied by a scale factor.
To view the displacement shape in real scale, you need to set the appropriate option.
During the construction phase when activating boundary conditions, the Original option applies a load that restores the node to its initial position, generating additional member forces.
On the other hand, the Deformed option creates boundary conditions as is, with the displacement that occurred at the node, so no additional member forces occur under this option.
For consistency with the member forces during actual structural construction, it is appropriate to analyze using the Deformed option. Since it does not forcibly apply displacement to the structure, it is common to apply the displacement that occurs after analysis with the Deformed option as camber.