Section 4 — Structures and Foundations

Pile Foundation

IPE Engineering Practice IPE-EP-4-2-4

Document number: IPE-EP-4-2-4 · Section: 4 — Structures and Foundations

SCOPE

This Practice contains general requirements for the material, design, construction, and installation of piles (except sheet piling) for all land and marine construction. Drilled piles and caissons are covered in EP 4–2–6.
Any deviation to this Practice must be approved by procedures described in EP 1–1–3.
An asterisk (*) indicates that a decision or approval by the Owner or the Owner’s Engineer is required, or that additional information is furnished by the Purchaser.
A revision bar indicates all changes made to this Revision.
Documentation required for pile foundations in accordance with this Practice is given in Table 1.

2.0 REFERENCES

The latest edition of the following standards and publications are referred to herein.

STANDARDS AND PUBLICATIONS

IPE Engineering Practices
EP 1–1–3 Deviations to IPE Engineering Practices EP 4–2–1 Foundation Types and Selection Criteria EP 4–2–4C Pile Foundation Inspection Checklist EP 4–2–6 Drilled Cassion Foundations
ACI Standards
543 Recommendations for Design, Manufacture. and Installation of Concrete Piles
AlSC Publication
Specification for the Design, Fabrication, and Erection of Structural Steel for Buildings
APl Standard
5L Line Pipe
ASTM Standards
A36 Structural Steel A252 Welded and Seamless Steel Pipe Piles A615 Deformed and Plain Billet Steel Bars for Concrete Reinforcement C33 Concrete Aggregates C150 Portland Cement D25 Round Timber Piles D1586 Penetration Test and Split - Barrel Sampling of Soils D2166 Unconfined Compressive Strength of Cohesive Soil D2899 Establishing Design Stresses for Round Timber Piles

STANDARDS AND PUBLICATIONS (CONT.)

American Wood-Preservers Association (AWPA) Standards
C3 Piles, Pressure Treatment M4 Care of Preservative Treated Wood Products
AWS Code
D1.1 Structural Welding Code
NAVFAC (U.S. Navy) Design Manuals
DM–7.02 Foundations and Earth Structures

DEFINITIONS

Contractor - Company or business that agrees to furnish materials or perform specified services at a specified price and/or rate to the Owner.
Inspector - A IPE Engineering Company appointed engineer or inspector.
Owner - Inflection Point Engineering, LLC .
Owner’s Engineer - A Inflection Point Engineering, LLC appointed engineer.
Pile - Structural member of timber, concrete, and/or steel, used to transmit surface loads to lower levels in the soil mass.
Unconfined Compressive Strength - Load per unit area at which an unconfined cylindrical soil sample will fail in a simple compression test. This test shall be performed in accordance with ASTM D2166.
Standard Penetration Resistance - Number of blows required to drive a standard sampling device for a distance of 12 inches into the soil. This test shall be performed in accordance with ASTM D1586.

MATERIALS

Wood piles shall be per ASTM D25 and D2899, and the following:
Foundation piles shall be pressure treated per AWPA C3 for foundation piles.
Marine piles shall be pressure treated per AWPA C3 for marine piles.
(*)Proposals to use species other than those in AWPA C3 or to use untreated timber piles shall be submitted for approval by the Owner.
Preservative–treated piles shall be protected and surface injuries treated per AWPA M4.
(*)Documentation of the grade and specification of timber shall be provided to the Owner’s Engineer.
Steel pipe piles shall be per ASTM A252 Grade 2 or 3, API 5L, Grade B, and the following:

(*)Strength of welds (shop and field) including the type of joint preparation and percent penetration shall be developed for the specific application and submitted to Owner for approval. Welding procedure and welder qualification shall be per AWS D1.1.
Complete penetration welds are required for all piles that will be subjected to tensile or flexural stresses.
Pipe smaller than 8 inches outside diameter (OD) shall not be used.
Minimum pipe wall thickness shall be determined based on load capacity, soils conditions and pile driving conditions. However, a minimum of 1/4 inch, including corrosion allowance, shall be used.
A minimum corrosion allowance of 1/16 inch shall be added to the calculated wall thicknesses.
(*)Documentation of the grade and specification of steel pipe piles shall be provided to the Owner’s Engineer.
Structural steel piles (H or I sections) shall be per ASTM A36.
Documentation of the grade and specification of structural steel piles shall be provided to the Owner’s Engineer.
(*)Concrete piles shall be per ACI publication 543. Unless otherwise approved by the Owner, reinforcing steel shall be ASTM A615, Grade 60, cement shall be ASTM C150 (Type to be specified according to soil properties) and aggregate shall conform to ASTM C33.
(*)Documentation of materials used in construction of concrete piles shall be provided to the Owner’s Engineer.
(*)Pre–stressed or post–tensioned concrete piles shall not be used without the approval of the Owner’s Engineer.

FIELD INVESTIGATION

An adequate geotechnical investigation shall precede the design of pile foundations. This investigation shall include the following:

Geological section showing pattern of major strata and presence of possible obstructions, such as boulders, buried debris, etc.
Sufficient test data to estimate strength and compressibility parameters of major strata., including, as a minimum, the following data:
In clays: the unconfined compressive strength, the dry density, and the moisture content.
In sand, silt and gravel: the Standard Penetration Resistance, the dry density, and the moisture content.
Determination of probable pile bearing stratum.
The results of the geotechnical investigation, including load capacity data for proposed pile details, shall be recorded in a report submitted by the Geotechnical Engineer.

DESIGN GUIDELINES

(*)Selection of pile types, allowable loads, spacing, and embedment in supporting soil shall be approved by the Owner and shall be based on results of a geotechnical investigation at the site where piles are to be driven. See EP 4–2–1 for requirements on soils investigations.
Minimum spacing (center to center)shall be as follows:
Piles to rock: 2.5 times the average pile diameter or 2 times the diagonal dimension of pile cross section, but no less than 24 inches.
All other piles: 2.5 times the average diameter of the pile or 2 times the diagonal dimension of pile cross section, but no less than 30 inches. In addition, the minimum spacing shall be limited by the requirement that the pile load distributed into the bearing stratum shall not exceed the nominal bearing capacity of the stratum.
Minimum number of piles in a group shall be based on design loads and the following:
(*)Pile groups supporting superstructure loads shall consist of at least 3 piles, except where pilecaps are restrained or laterally supported by grade beams or other means that are approved by the Owner.
Single pile supports shall be used if the pile has a butt diameter of 12 inches or greater, if the upper soils are not of a weak nature, and if proper consideration is given to reinforcement of column and pile to accommodate potential eccentricities.
All tops of piles shall extend at least 4 inches into the pile cap except wood piles that shall extend 6 inches.
The design methods described in NAVFAC DM–7.02 manual shall be used to determine pile lengths based on the shear strength data obtained during the soil investigation.
Tolerances in pile location and alignment shall be as follows:
Vertical piles shall not vary more than 2 percent from the plumb position.
No pile shall be driven more than 4 inches in horizontal dimension from its design location, unless the effect of this deviation is analyzed and found acceptable.
Eccentricity of reaction of the pile group with respect to the load resultant shall not exceed a dimension that would produce overloads of more than 10 percent in any pile.
Pile groups shall be driven from the interior outward to preclude densification and excessively hard driving conditions on the interior.
Allowable overload of piles shall be as follows:
Up to 10 percent overload is permitted due to eccentricity of reaction of the pile group.
Overload due to wind is permitted if it does not exceed 33 percent of allowable capacity of pile under dead plus live loads.
No lateral load is permitted on vertical piles in very soft fine–grained soils or very loose coarse– grained soils. For piles with unsupported length or for larger horizontal loads, use batter piles or use analysis to determine lateral load capacity of vertical piles.

In a group of bearing piles, all bearing piles shall be of the same type and be of equal load capacity.
Maximum allowable pile load shall be limited by both allowable stresses in the pile and supporting capacity of the soil.
Static and dynamic pick–up loads induced flexural stresses incurred during pick–up and placement of long concrete piles shall not exceed the allowable bending stresses prescribed for that pile length.
Splices shall be able to transmit the resultant vertical and lateral forces adequately.

PILE INSTALLATION

(*)Unless otherwise specified, the proposed pile installation procedure and plan, elevation and detail drawings shall be submitted to Owner’s Engineer for approval.
(*)For each pile, accurate records shall be kept of number of blows required to drive each foot, complete hammer data and stroke, details of anvil and cushion, driving time, and elevations of pile tip and top before and after cutting off extra lengths. These records shall be provided to the Owner’s Engineer. Additional field inspection shall be recorded on EP 4–2–4C.
All top–driven piles shall be protected during driving by cushioned caps.
(*)Where vibration due to pile driving may be harmful to existing equipment and structures, piles shall be installed by other methods as approved by Owner.
(*)Unless otherwise specified by the Owner’s Engineer, piles shall be driven with a Vulcan No. 1 single acting compressed air hammer, developing a minimum of 15,000 foot–pounds of energy per blow. Actual pile hammer size will depend on several factors including, but not limited to, pile type, pile diameter and length, and soils resistance.
Driving of piles shall be continuous to the final elevations and resistances.
Leads shall be used to secure piles against lateral movement during driving.
When the minimum tip elevations specified on the plans cannot be attained due to hard driving, jetting or pre-drilling may be used if approved by the Owner, see EP 4–2–6.
Position of piles shall be considered satisfactory, provided the following conditions are met:
Pile tops are within 4 inches of the location specified by design drawings and adequate penetration into the pile cap in ensured.
Piles are within 2 percent of the specified slope.
The piles, as finally placed, are not structurally damaged.
Piles have not heaved more than 1/4 inch during driving of adjacent piles.
Eccentricity of reaction of the pile group with respect to the load resultant shall not exceed a dimension that would produce overloads of more than 10 percent in any pile.
(*)Repairs or changes due to improper placement of piles or due to structural damage shall be made as directed by the Owner’s Engineer. This may include re-driving of piles or the addition of new piles. Damaged piles shall be replaced at the expense of the pile–driving contractor.

The following requirements for steel encased cast–in–place piles shall be met:
Casings shall be inspected after driving the shells and prior to filling them with concrete.
Casings shall be free of water. If water is found in the casing, the piling contractor shall demonstrate that it is not due to structural damage of the casing.
New shells shall not be driven inside a closed–end thin–shell pile for repair.
Concrete placement for cast–in–place piles shall be per ACI 543, Section 5.5.

8.0 TABLES

TABLE 1

DOCUMENTATION REQUIREMENTS FOR PILE FOUNDATIONS PER EP 4–2–4

Item	Description	Format	As–Built
1	Documentation of the grade and specification of timber, steel or concrete materials used in piles.	Text	N/A
2	Geotechnical Engineer’s report.	Text	N/A
3	Pile installation procedures.	Text	N/A
4	Plan, elevation and detail drawings for pile installations.	CALS G4 TIFF (Compressed)	Yes
5	Records of file data and inspection taken or performed during or after pile driving.	Text	Yes

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