Columns design as per ACI 318-14 is based on a full 3D interaction surface for a given cross section. Columns will be designed for the combined effects of axial loads and bi-axial bending moments. Other effects such as torsion and shear will also be accounted for in the design. The program then provides a final detailed design followed by a cross section wise analysis to ensure that the design is satisfactory. During the analysis stage the strengths of the cross section for each of these effects will also be calculated. The design process works on the basis of being able to find a point on or very close to the interaction surface so as to ensure the most efficient design.

As with beam design, an envelope is created at each design section from a collection of the max/min forces in all degrees of freedom for all the load cases and combinations that have been included in the design. As there are six degrees of freedom (Fx, Fy, Fz, Mx, My, Mz) and to capture the maximum and minimum effects, a total of 12 sets of loads are designed for. Each set will include the maximum or minimum of one force such as Max FX along with all the other associated forces in the load case/combination.

All column designs will be based on a uniform distribution of reinforcement around the column perimeter. The design options to control a column design will be based on the CRDO parameter setting.