Applies To
	Product(s):	STAAD Advanced Concrete Design
	Version(s):	Connect Edition
	Environment:
	Area:	Concrete Design
	Subarea:	Footing Design
	Original Author:	Aaradhya Rahate, Bentley Technical Support Group

While designing for reinforcement requirement, it was observed that RCDC considers only super-structure support reaction. Ideally the effective extra weight of foundation replacing the existing soil should also be considered for the vertical load. So the additional loading from volume of the RCC potion under the ground level with an effective density [concrete density (25 kN/***) – soil density (18 kN/***)] should be added up with super-structure reaction.

For sizing check of footings where maximum and minimum soil pressure (or loss of contact) is checked (and also other checks), we add the weight of footing and weight of soil. Following are possible cases –

1. User chooses ‘Yes’ to option – Consider Overburden – In this option we add load of soil and self-weight of footing

2. User chooses ‘No’ to option – Consider Overburden – In this option we add self-weight of footing

 When it comes to design of cross-section, the BM and shear is calculated using the pressure from bottom. In this case, the vertical load due to self-weight of footing and soil is uniformly distributed and it gets off-set by equivalent pressure from below. So net pressure causing the bending from bottom is the pressure due to reactions from super-structure load. In other words, if one considers pressure from bottom (including soil and self-weight) for calculation of BM and shear then, one will have to deduct the load from top (due to self-weight and soil) as it would oppose it. Hence in the design of cross-section, the weight of footing and soil have no impact.