Does on raft footing option design the additional reinforcement for each column for a raft foundation beacuse when we deaign on raft footing it is designed as isolated stepped footing and not acommon raft .
HiOn raft footing is similar to Stepped footing. in metro cities where Building are constructed with basements, the common raft is provided with upstand footings. Generally common raft is resisting the upward water pressure and footings are designed for vertical loads. The footings are connected with common raft.where footings are connected with common raft, stepped footings can be design with thickness of first step as thickness of raft. so the thickness of first step can be same for all stepped footing. When you select the On raft footing options, there is a input available to provide thickness of raft. RCDC will design all the footing with same thickness of first step.there is no difference in the design of stepped and on Raft footing Only the thickness of first step same in On raft option.