What are rectangular combined footings?
Rectangular Combined Footings:
In the design of rectangular combined footings it is assumed that the footing is rigid. Soil pressure will then be linear. If the line of action of the resultant of the forces acting on the columns passes through the centroid of the footing area, the soil reaction will be uniform.
Though the assumption of a rigid foundation is questionable, the method has been successfully used for the design of combined footings. The combined footing can also be analysed on the assumption that the footing is flexible by beam on elastic foundation analysis approach. This analysis produces smaller design moments than those obtained by the rigid method and is realistic.