How to Assign Column Base Boundary Conditions in RISAFloor

Column boundary conditions are set in RISAFloor per the Splice Type that you have set in the Columns spreadsheet.

For any column at the lowest floor level, the Splice checkbox will automatically be checked, indicating that a boundary condition will be set at the base. You may set the boundary condition to either pinned or fixed. This is controlled through the Splice Type.

Setting the Splice Type to Moment creates a fixed boundary condition; setting it to Shear creates a pinned boundary condition.

After solving your model and taking it into RISA-3D via the Director tool, you will be able to verify these boundary conditions.

Note: After the initial export into RISA-3D, the splice type is no longer linked to the model. Therefore, you have the ability to modify these boundary conditions once in RISA-3D.

This way, you have the freedom to release any restraint (in each of the six directions), rather than selecting just perfectly pinned or perfectly fixed for your lateral analysis.