Section 6.2.3 of AS3600-2009 states "The critical section for maximum negative bending moment may be taken at 0.7 times the length of the support in the direction of the span (a,sup) from the centre-line of the support."
When design strips are setup in Ram to 'detect supports and edges automatically' the first and last cross sections will occur at the column face, to my understanding Ram then uses the moment at this section to determine the design bending moment for reinforcement over that column. In typical flat slabs this would be unconservative as the moment at a,sup is greater than the moment at the face of the support.
Therefore to ensure I am designing for the critical negative bending moment over columns in accordance with AS3600 I believe I need to manually specify the 'support width' at each end of each span to at a,sup.
Can you please advise/confirm?
Yes, automatic support detection will be at the face of a rectangular column but you can override this and use a smaller support width resulting in a longer span if needed.