## Footings subject to vertical actions

For a spread foundation subject to vertical actions, Eurocode 7 requires the design vertical action Vd acting on the foundation to be less than or equal to the design bearing resistance Rd of the ground beneath it:

Vd should include the self-weight of the foundation and any backfill on it. This equation is merely a re-statement of the inequality:

Ed < Rd discussed at length in Chapter 6. Rather than work in terms of forces, engineers more commonly consider pressures and stresses, so we will rewrite this equation as:

fwhich also appear in BS 8004.

qEd - qRd where qEd is the design bearing pressure on the ground (an action effect), and qRd is the corresponding design resistance.

Figure 10.4 shows a footing carrying characteristic vertical actions VGk (permanent) and VQk (variable) imposed on it by the super-structure. The characteristic self-weights of the footing and of the backfill upon it are both permanent actions (WGk). The following sub-sections explain how qEd and qRd are obtained from VGk, VQk, WGk, and ground properties.

10.4.1 Effects of actions

The characteristic bearing pressure qEk shown in Figure 10.4 is given by:

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