## Rd And Ed In Structural Calculation

discussed at length in Chapter 6.

Figure 13.6 shows a single pile subject to an imposed vertical action T, which attempts to pull the pile out of the ground. The uplift force is countered somewhat by the pile's self-weight W and the total vertical tensile action that results is Ft.

The characteristic value of Ft is given by:

where TGk and TQk are characteristic permanent and variable components of T, respectively; the symbol WGk represents the pile's characteristic self-weight (a favourable permanent action); and ^ is the combination factor applicable to the ith variable action (see Chapter 2).

The design value of Ft is given by:

and TQk are characteristic

Qk i where yg and yq are partial factors on unfavourable permanent and variable actions and YGfav (= 1.0) is a partial factor on favourable permanent actions. Since it is conservative to do so, the pile's self-weight is often omitted from traditional calculations of pile pullout.

The characteristic tensile resistance Rtk of the pile is given by:

Rtk = Rstk where Rstk is the characteristic tensile shaft resistance. It is assumed that the base offers no resistance to pullout.

The design value of Rt is given by:

Yst where Yst is a partial factor on shaft resistance in tension. Values of the partial factor Yst are greater than ys to reflect the potential consequences of failure.

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