A flat slab is a two-way reinforced concrete slab that usually does not have beams and girders, and the loads are transferred directly to the supporting concrete columns. to minimize the effect of punching shear, the slab thickness at the near column zone is increased which is normally known as Drop-cap. The normal geometry look like--
This can be modeled in STAAD.Pro by using varying thickness plate element and master -slave specification.
1. Create the column slab geometry using line member and plate elements. The plate should be meshed properly using quadrilateral elements.
2. Assign uniform thickness to all plate elements
3. To model the drop-cap, select the portion of slab that is adjacent to the column (the dimension of the drop panel depends on user requirement) > Assign a thickness of the drop-cap (normally it is greater than the thickness of the slab, mentioned as d2 in the above figure)
4. To model the column head, insert an additional node on the column member at the depth d1 (highlighted in the figure) > Go to Specification > Node > Add Control/Dependent Specification > Select this node as a Control node and all the nodes within the drop slab region as Dependent nodes.
The Control/Dependent option creates a stiff connection between these points. This can also be modeled using very stiff line element.