Plain concrete foundations

Strip and pad footings may be constructed from plain concrete provided the following rules are adhered to.

■ In compression, the value of acc, the coefficient taking account of long-term effects applied to design compressive strength

(see CI. 3.1.6), should be taken as 0.6 as opposed to 0.85 for reinforced concrete.

■ The minimum foundation depth, hF, (see Figure 8) may be calculated from:

9ogd

0.85 V/ctd

Table 8

Minimum percentage of reinforcement required where:

CTgd = the design value of the ground bearing pressure /ctd = the design concrete tensile strength from Exp. (3.16)

For many situations this is unlikely to offer any savings over the current practice of designing for hf > a.

The possibility of splitting forces, as advised in Clause 9.8.4 of Eurocode 2-1-1, may need to be considered.

Eurocode 2 allows plain concrete foundations to contain reinforcement for control of cracking.

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