Generally the unbalanced moments can be split for design of the columns, with part of the moment going to the column above the joint and part of the moment going to the column below the joint. At a joint where the column above and below differ in either shape, material, or orientation in the plane of the cross-section, the whole unbalanced moment is applied to the top of the column below. In reality, the unbalanced moment split is based on column continuity, column length, column moment of inertias, presence or absence and type of column splices, and bracing conditions.

The program currently cannot resolve this split for the following cases: (a) there is more than one column at a joint and the joint is unbraced in one or two axis directions and (b) the relative angle between the columns below and above the joint is not zero and the joint is unbraced. Hence in the Design All situation the columns at the joint are tagged as cannot design. A user may assign a size to such columns using View/Update but the program does not check them for adequacy.

Except as noted below, to simplify the analysis the assumption is made that the design moment distributed to each column is inversely proportional to its length. By making this assumption the distribution of moments is very much simplified. It should be noted that when calculating the moment splits by hand, it is common practice to make this same assumption.