BS8110 Clause 3.7.2.9 states the following:

"Columns strips between unlike panels: Where there is a support common to two panels of such dimensions that the strips in one panel do not match those in the other, the division of the panels over the region of the common support should be taken as that calculated for the panel giving the wider column strip."

The column strips in the following example are modified with logic derived from this clause.

The following three figures show the use of strip boundaries to control the column strip width

Slab with span segments.

Strips generated from the span segments in the previous figure.

Strip boundaries have made transitioning column strip widths

The following four figures show the use of strip boundaries to control the column strip width.

Slab with span segments

Strips generated from the span segments in previous figure. One span (with gray shading) has illogical span width and column strip width.

Span boundaries have made a logical span width, but the column strip width is still a problem.

Strip boundaries have made a logical column strip width.

Short spans and cantilevers present problems for the design because RAM Concept will generate narrow column strips.

Codes recommend that columns strips are no more than half the span in width. RAM Concept makes the (commonly used) assumption that the equivalent length of a cantilever is 2L. The cantilever column strip width is thus L. This can be quite narrow for short cantilevers.

Slab with span segments

Strips generated from the span segments in previous figure.

Strip boundaries have made a logical column strip width.