Starting with Advance Design 2011, you can define releases for each side of planar elements.
As an example we will use the outer shape of a staircase landing. We consider a set to consist of a structural wall (made of C20/25 concrete 20 cm thick, 5 meters long and 3.5 meters height) and a landing (also made from concrete C20/25, but with a plate thickness of 15 cm, 2 meters long and 2 meters wide), of the type shown below:
Note: Both landing and structural walls are made as planar elements.
The landing is considered hinged on the side that is supported by the vertical structural element. Select the "Releases" section in the properties window of the landing. For the "Side" option select "Other" and then choose the releases for the hinged side of the landing.
Next compare the set with the hinged side landing and the set with the fixed side landing. The size of the mesh element is set to 0.2 meters. On the landing, define a dead load of 3 kN/m2, and proceed to compare the results.
The following figure shows the deformed shape for both analyzed cases. As can be seen the rate of deformation curves is in agreement with the boundary conditions chosen for each case.