# A.3.3.3 Correlation factors for pile foundations

(1) P For verifications of structural (STR) and geotechnical (GEO) limit states, the following correlation factors ξ shall be applied to derive the characteristic resistance of axially loaded piles:

• ξ1 on the mean values of the measured resistances in static load tests;
• ξ2 on the minimum value of the measured resistances in static load tests;
• ξ3 on the mean values of the calculated resistances from ground test results;
• ξ4 on the minimum value of the calculated resistances from ground test results;
• ξ5 on the mean values of the measured resistances in dynamic load tests;
• ξ6 on the minimum value of the measured resistances in dynamic load tests.

NOTE The values to be ascribed to ξ1, ξ2, ξ3, ξ4, ξ5 and ξ6 for use in a country may be found in its National annex to this standard. The recommended values are given in table A.9, in table A.10 and in table A.11.

Table A.9 – Correlation factors ξ to derive characteristic values from static pile load tests (n – number of tested piles)
 ξ for n = 1 2 3 4 ≥ 5 ξ1 1,40 1,30 1,20 1,10 1,00 ξ2 1,40 1,20 1,05 1,00 1,00

Table A.10 – Correlation factors ξ to derive characteristic values from ground test results (n – the number of profiles of tests)
 ξ for n = 1 2 3 4 5 7 10 ξ3 1,40 1,35 1,33 1,31 1,29 1,27 1,25 ξ4 1,40 1,27 1,23 1,20 1,15 1,12 1,08

Table A.11 – Correlation factors ξ to derive characteristic values from dynamic impact tests a, b, c, d, e (n – number of tested piles)
 ξ for n = ≥ 2 ≥ 5 ≥ 10 ≥ 15 ≥ 20 ξ5 1,60 1,50 1,45 1,42 1,40 ξ6 1,50 1,35 1,30 1,25 1,25 a The ξ-values in the table are valid for dynamic impact tests.b The ξ-values may be multiplied with a model factor of 0,85 when using dynamic impact tests with signal matching.c The ξ-values should be multiplied with a model factor of 1,10 when using a pile driving formula with measurement of the quasi-elastic pile head displacement during the impact.d The ξ-values shall be multiplied with a model factor of 1,20 when using a pile driving formula without measurement of the quasi-elastic pile head displacement during the impact.e If different piles exist in the foundation, groups of similar piles should be considered separately when selecting the number n of test piles.

A.3.3.4 Partial resistance factors for pre-stressed anchorages

(1)P For pre-stressed anchorages and verifications of structural (STR) and geotechnical (GEO) limit states, set R1, R2, R3 or R4 of the following partial factors on resistance (γR) shall be applied:

• γa;t on temporary anchorages;
• γa;p on permanent anchorages.

NOTE The values to be ascribed to γa;t and γa;p for use in a country may be found in its National annex to this standard. The recommended values for the four sets R1, R2, R3 and R4 are given in table A.12.

Table A.12 – Partial resistance factors (γR) for pre-stressed anchorages
 Resistance Symbol Set R1 R2 R3 R4 Temporary γa;t 1,1 1,1 1,0 1,1 Permanent γa;p 1,1 1,1 1,0 1,1

Eurocode 7 Geotechnical design Part 1 : General rules