4 Requirements

4.1 Material requirements

For general aspects, constituent materials of concrete, reinforcing and prestressing steel, inserts and connectors the relevant Clauses of EN 13369:2004 4.1 shall apply. The ultimate tensile and tensile yield strength of steel shall be considered.

4.2 Production requirements

4.2.1 Concrete production

4.2.1 of EN 13369:2004 shall apply.

4.2.2 Hardened concrete

4.2.2.1 Strength classes

4.2.2.1 of EN 13369:2004 shall apply.

The minimum concrete class for either reinforced or prestressed precast foundation piles shall be C35/45.

4.2.2.2 Compressive strengths

4.2.2.2 of EN 13369:2004 shall apply.

The minimum compressive strength to achieve before transportation or when applicable also before installation of the pile shall be specified.

4.2.3 Structural reinforcement

4.2.3.1 Processing of reinforcing steel

4.2.3.1 of EN 13369:2004 shall apply.

4.2.3.2 Tensioning and prestressing

4.2.3.2.1 Initial tensioning stresses

4.2.3.2.1 of EN 13369:2004 shall apply.

4.2.3.2.2 Accuracy of tensioning

Class A of 4.2.3.2.2 of EN 13369:2004 shall apply.

4.2.3.2.3 Minimum concrete strength at transfer

4.2.3.2.3 of EN 13369:2004 shall apply.

4.2.3.2.4 Slippage of tendons

Not relevant due to the common production technique.

4.3 Finished product requirements

4.3.1 Geometrical properties

4.3.1.1 Production tolerances

The following tolerances shall apply unless stricter tolerances are specified for single piles or pile segments:

  • the axis of the pile shaft after production and without the influence of bending stresses shall be straight. The permitted production deviation of straightness is shown in Table 2;
  • for cross-sectional dimensions L, the permitted deviation is ΔL from nominal dimensions, see Table 2;
  • the top and bottom of the pile shall be perpendicular and symmetric to the central axis of the pile. The angular deviation shall not exceed the following values in class AD1 or class AD2 as shown in Table 1:
Table 1 — Classes of maximum angular deviation of the pile
Class Maximum permitted deviation
Class AD1 1/100 across the cross section
Class AD2 3/100 or 10 mm across the cross section whichever is less
  • The top of the pile shall be either plane or convex.
  • Axis of any enlarged toe shall be nominally concentric to the axis of the pile shaft. Maximum permitted deviation is de/100 or 20 mm across the cross section whichever is the less. where de = depth of the cross-section of enlarged toe;
  • for positioning of reinforcing and prestressing steel the permitted deviation is Δd from nominal effective depth d of the reinforcement and Δc from nominal cover c nom of the reinforcement, see Table 2. For the single bar pile see Annex C;
  • cover of each reinforcing bar from the pile top and pile bottom shall be within the limits of 10 mm to 50 mm, while the mutual difference between the ends of reinforcing bars shall be less than 20 mm, which is not valid for the single bar pile described in Annex C;
  • when determining the deviation from nominal effective depth the location of the reinforcement may be determined as the mean of the measured values of the bars or strands in a cross section;
  • the nominal cover c nom of the reinforcement shall be not less than the minimum cover c min plus the lower permitted deviation Δc;
  • the position of the reinforcement and its tolerances shall be specified in production drawings.

The requirements shall be verified in accordance with 5.2.

Table 2 — Permitted deviations for dimensions and cover of precast concrete piles
Target dimension of the cross-section in the direction to be checked ΔL
(mm)
Δd
(mm)
Δc
(mm)
Cross-section dimensions of the pile
 The actual cross section shall be greater than 95 % of the nominal cross section
+ 15
– 10
– 10 – 10
Nominal length of the pile + 150
– 100
   
Straightness of the axis of the shaft
L ≤ 10 m
10 m ≤ L < 20 m
L ≥ 20 m
 
± 20
± 2 L1
± 40
   
NOTE 1 ΔL and Δd are given to ensure that deviations in either cross-sectional dimensions or lengths as well as in the position of the reinforcement do not exceed values covered by the relevant safety factors in the Eurocodes. NOTE 2 The values for Δc are given for durability purposes.
1 In this formula the dimension of length L is m.

4.3.1.2 Minimum dimensions

The shape factor shall not exceed the following values:

  • Multiple bar reinforced piles/pile segments 75
  • Prestressed piles 100

The dimensions of an enlarged toe shall be in compliance with Figure 2.

Requirements for the dimensions of the toe  
 
shaft
  
  


a ≥ b
 
 
 
 
c ≥ 500 mm and c ≥ de
 
 
 
 
 
de ≤ 1,6 e

Key

  • 1 Axis
Figure 2 — Requirements for the dimensions of the toe

The requirements shall be verified in accordance with 5.2.

4.3.1.3 Pile joints

The steel components of the pile joint shall be integrated in the pile segments to be joined. They shall be cast in, in such a way, that their position can be inspected during production and on the finished product.

The quality of the further structural parts, e.g. locking parts, necessary to complete the actual joining of the pile segments at the site of installation, shall be the pile producer’s responsibility.

The site assembly of pile joints is not covered by this document.

Pile joints shall locate and maintain a coaxial connection between pile segments. The faces of the pile components shall be perpendicular to the axis of the pile segments within the following tolerances:

  • centres of cast in components shall not deviate more than 10 mm from the central axis of the pile/pile segment;
  • angular deviation of the faces of the pile components shall not exceed an inclination of 1:150. Coaxial and angular deviation shall be verified in accordance with 5.2.

The classification of pile joints is specified under 4.3.8.3.

4.3.1.4 Pile shoes

Pile shoes, when fitted shall be coaxial with the pile. The face of the pile shoe shall be perpendicular to the axis of the pile within the following tolerances:

  • central axis of the pile shoe shall not deviate more than 10 mm from the central axis of the pile/pile segment;
  • angular deviation of the face of the pile shoe shall not exceed an inclination of 1:75.

Coaxial and angular deviation shall be verified in accordance with 5.2.

4.3.2 Surface characteristics

Not relevant.

4.3.3 Mechanical resistance

4.3.3.1 General

4.3.3 deals only with the nominal mechanical strength of the pile itself. The bearing capacity of the pile in its final position on site also depends on the geotechnical considerations, which are out of the scope of this document.

4.3.3.1 of EN 13369:2004 shall apply.

Due to the position of the reinforcement in the single bar pile and the absence of confining reinforcement in the shaft of this type of pile, the piles in this document are divided into the classes defined in Table 3.

Table 3 — Classifications of piles
Class Pile type
1 Piles or segmental piles with distributed reinforcement and/or prestressed reinforcement with or without an enlarged pile toe, see also Annex B
2 Piles or segmental piles reinforced with single centrally placed bars, see Annex C

4.3.3.2 Verification by calculation

4.3.3.2 of EN 13369:2004 shall apply.

4.3.3.2.1 Verification of the resistance for transportation

The characteristic concrete strength at time of transportation, as specified in 4.2.2 shall be used in verification of the resistance according to 4.3.3.2 of EN 13369:2004 with the complementary rules given in Annex B.

4.3.3.2.2 Verification of the resistance for pile installation

The characteristic concrete strength at time of pile installation shall be used in verification of the resistance for pile installation. The verification of the resistance for pile installation shall conform to relevant documents or other provisions valid in the place of use taking in consideration the specific geographical conditions which refer specifically to the installation of the precast concrete foundation piles.

NOTE 1 Provisions for pile installation may give higher minimum requirements for the concrete class and reinforcement than specified in 4.2 of this document.

NOTE 2 Guidance for the execution of pile foundations is given in EN 12699.

NOTE 3 Provisions regarding the soil conditions in the place of use can be given for pile type — Class 2 — as specified in Annex C.

4.3.3.2.3 Resistance to design loads

Resistance to design loads at the critical section of the pile shaft shall (e.g. near the joint) be verified by the calculation in accordance with 4.3.3.2 of EN 13369:2004.

NOTE The calculated resistance of the pile cross section with respect to the axial force will be at least equal to the geotechnical load bearing capacity of the installed foundation pile.

4.3.3.3 Verification by calculation aided by physical testing

4.3.3.3 of EN 13369:2004 shall apply.

4.3.3.5 Safety factors

4.3.3.5 of EN 13369:2004 shall apply.

4.3.3.6 Transient situations

4.3.3.6 of EN 13369:2004 shall apply.

4.3.4 Resistance and reaction to fire

Not relevant.

4.3.5 Acoustic properties

Not relevant.

4.3.6 Thermal properties

Not relevant.

4.3.7 Durability

4.3.7 of EN 13369:2004 shall apply.

The specific tolerances for piles given in 4.3.1.1 and Annex C shall be considered.

Concrete composition shall be appropriate to exposure class of the soil conditions of the site.

4.3.8 Other requirements

4.3.8 of EN 13369:2004 shall apply, with the following additional requirements.

4.3.8.3 Rigidity of pile joints

The producer shall declare the class of the pile joint and the relevant capacity values.

Pile joints shall be classified in the classes indicating the required capacities, performance and type of verification methods. The classification is shown in Table 4.

Table 4 — Classification of pile joints
Class 3 Capacity Performance Verification Methods Impact load test 1
A Compression/tension and bending Robustness and rigidity Static calculations to be verified by impact testing and subsequent bending test. Impact load test with 1 000 impact blows having stress level 28 N/mm2.2
B Compression/tension and bending Robustness and rigidity Static calculations to be verified by impact testing and subsequent bending test. Impact load test with 1 000 impact blows having stress level 22 N/mm2.2
C Compression/tension and bending Robustness and rigidity Static calculations to be verified by impact testing and subsequent bending test. Impact load test with 1 000 impact blows having stress level 17 N/mm2.2
D Compression Robustness and rigidity Static calculations to be verified by impact testing. Impact load test with 500 impact blows having stress level 17 N/mm2.2
1 IBT = Impact load test with subsequent bending test as defined in Annex A.
2 Stress level means: compressive stresses around the pile joint caused by impact blows.
3 Pile joint class (i.e. the dynamic stress level during Impact load test) is chosen according to national provisions to correspond the target geotechnical capacity of the segmental pile.

NOTE Pile joints with better class than specified in the piling specification may be used.

For the pile joints connected with the pile segment, the pile joint class, gap width, calculated characteristic static bearing capacity (i.e. compression, tension and bending capacity) shall be declared as well as the flexural stiffness at the level of 0.75 x calculated ultimate bending moment.

Robustness and rigidity of pile joints shall be verified by impact loading testing followed by subsequent bending testing in conformity with the procedures and methods given in Annex A.

Class A, B and C:

The ultimate bearing capacity (compression, tension and bending) of the pile joint shall be calculated taking in account the design strengths of materials. Provided that the impact load test and subsequent bending test can verify the static calculations, then the ultimate bearing capacity of the joint is identical to the static calculated bearing capacity.

Robustness and rigidity may be deemed adequate if the pile joint performs satisfactorily in the test indicated in Annex A.

Class D:

The ultimate bearing capacity (compression) of the pile joint shall be calculated taking in account the design strengths of materials. Provided that the impact load test can verify the static calculations, then the ultimate bearing capacity of the joint is identical to the static calculated bearing capacity.

Robustness and rigidity may be deemed adequate if the pile joint performs satisfactorily in the test indicated in Annex A. In this case the subsequent bending test is not performed.

EN 12794:2005 Precast concrete products – Foundation piles