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tValue not given in EN 1997-1, but may be specified in National Annex ^Partial factors for accidental design situations are 1.0

13.7.2 Design Approach 1

As discussed in Chapter 6, the philosophy of Design Approach 1 is to check reliability with two different combinations of partial factors.

In Combination 1 for pile foundations, partial factors are applied to actions and small factors to resistances, while ground strengths (when used) are left unfactored. This is achieved by employing factors from Sets A1, M1, and R1, as illustrated in Figure 13.9. The crosses on the diagram indicate that the factors in Set Ml are all 1.0 (and hence strengths are, in effect, unfactored) and that tolerances Aa are not routinely applied to dimensions.

In Combination 2, partial factors are applied to resistances and to variable actions, while permanent actions and ground strengths (when used) are left unfactored. This is achieved by employing factors from Sets A2, Ml, and R4, as illustrated in Figure 13.10. Once again, the crosses on the diagram indicate that the factors in Sets A2 and Ml are all 1.0 (except those applied to variable actions) and hence non-variable actions and strengths are unfactored.

Numerical values of the partial factors for Design Approach 1 are given below. See Section 13.11.1 for UK National Annex values for Sets R1 and R4.

Design Approach 1 Combination 1 Combination 2
0 0

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