International Building Code Section 1808


International Building Code 1808.1

Definitions. The following words and terms shall, for
the purposes of this section, have the meanings shown herein.
FLEXURAL LENGTH. Flexural length is the length of the
pile from the first point of zero lateral deflection to the underside
of the pile cap or grade beam.
MICROPILES. Micropiles are 12-inch-diameter (305 mm)
or less bored, grouted-in-place piles incorporating steel pipe
(casing) and/or steel reinforcement.
PIER FOUNDATIONS. Pier foundations consist of isolated
masonry or cast-in-place concrete structural elements extending
into firm materials. Piers are relatively short in comparison
to their width, with lengths less than or equal to 12 times the
least horizontal dimension of the pier. Piers derive their
load-carrying capacity through skin friction, through end bearing,
or a combination of both.
Belled piers. Belled piers are cast-in-place concrete piers
constructed with a base that is larger than the diameter of the
remainder of the pier. The belled base is designed to
increase the load-bearing area of the pier in end bearing.
PILE FOUNDATIONS. Pile foundations consist of concrete,
wood or steel structural elements either driven into the ground
or cast in place. Piles are relatively slender in comparison to
their length, with lengths exceeding 12 times the least horizontal
dimension. Piles derive their load-carrying capacity through
skin friction, end bearing or a combination of both.
Augered uncased piles. Augered uncased piles are constructed
by depositing concrete into an uncased augered
hole, either during or after the withdrawal of the auger.
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Caisson piles. Caisson piles are cast-in-place concrete piles
extending into bedrock. The upper portion of a caisson pile
consists of a cased pile that extends to the bedrock. The
lower portion of the caisson pile consists of an uncased
socket drilled into the bedrock.
Concrete-filled steel pipe and tube piles. Concrete-filled
steel pipe and tube piles are constructed by driving a steel
pipe or tube section into the soil and filling the pipe or tube
section with concrete. The steel pipe or tube section is left in
place during and after the deposition of the concrete.
Driven uncased piles. Driven uncased piles are constructed
by driving a steel shell into the soil to shore an unexcavated
hole that is later filled with concrete. The steel casing is
lifted out of the hole during the deposition of the concrete.
Enlarged base piles. Enlarged base piles are cast-in-place
concrete piles constructed with a base that is larger than the
diameter of the remainder of the pile. The enlarged base is
designed to increase the load-bearing area of the pile in end
bearing.
Steel-cased piles. Steel-cased piles are constructed by driving
a steel shell into the soil to shore an unexcavated hole.
The steel casing is left permanently in place and filled with
concrete.
Timber piles. Timber piles are round, tapered timbers with
the small (tip) end embedded into the soil.

International Building Code 1808.2

Piers and piles-general requirements.

Design. Piles are permitted to be designed in
accordance with provisions for piers in Section 1808 and
Sections 1812.3 through 1812.10 where either of the following
conditions exists, subject to the approval of the
building official:
1. Group R-3 and U occupancies not exceeding two stories
of light-frame construction, or
2. Where the surrounding foundation materials furnish
adequate lateral support for the pile.

General. Pier and pile foundations shall be
designed and installed on the basis of a foundation investigation
as defined in Section 1802, unless sufficient data
upon which to base the design and installation is available.
The investigation and report provisions of Section 1802
shall be expanded to include, but not be limited to, the following:
1. Recommended pier or pile types and installed capacities.
2. Recommended center-to-center spacing of piers or
piles.
3. Driving criteria.
4. Installation procedures.
5. Field inspection and reporting procedures (to include
procedures for verification of the installed bearing
capacity where required).
6. Pier or pile load test requirements.
7. Durability of pier or pile materials.
8. Designation of bearing stratum or strata.
9. Reductions for group action, where necessary.

Special types of piles. The use of types of piles not
specifically mentioned herein is permitted, subject to the
approval of the building official, upon the submission of
acceptable test data, calculations and other information
relating to the structural properties and load capacity of such
piles. The allowable stresses shall not in any case exceed the
limitations specified herein.

Pile caps. Pile caps shall be of reinforced concrete,
and shall include all elements to which piles are connected,
including grade beams and mats. The soil immediately
below the pile cap shall not be considered as carrying any
vertical load. The tops of piles shall be embedded not less
than 3 inches (76 mm) into pile caps and the caps shall
extend at least 4 inches (102 mm) beyond the edges of piles.
The tops of piles shall be cut back to sound material before
capping.

Stability. Piers or piles shall be braced to provide
lateral stability in all directions. Three or more piles connected
by a rigid cap shall be considered braced, provided
that the piles are located in radial directions from the centroid
of the group not less than 60 degrees (1 rad) apart. A
two-pile group in a rigid cap shall be considered to be
braced along the axis connecting the two piles. Methods
used to brace piers or piles shall be subject to the approval of
the building official.
Piles supportingwalls shall be driven alternately in lines
spaced at least 1 foot (305 mm) apart and located symmetrically
under the center of gravity of the wall load carried,
unless effective measures are taken to provide for eccentricity
and lateral forces, or the wall piles are adequately
braced to provide for lateral stability. A single row of piles
without lateral bracing is permitted for one- and two-family
dwellings and lightweight construction not exceeding
two stories or 35 feet (10 668 mm) in height, provided the
centers of the piles are locatedwithin thewidth of the foundation
wall.

Structural integrity. Piers or piles shall be
installed in such a manner and sequence as to prevent distortion
or damage that may adversely affect the structural
integrity of piles being installed or already in place.

Splices. Splices shall be constructed so as to provide
and maintain true alignment and position of the component
parts of the pier or pile during installation and
subsequent thereto and shall be of adequate strength to
transmit the vertical and lateral loads and moments occurring
at the location of the splice during driving and under
service loading. Splices shall develop not less than 50 percent
of the least capacity of the pier or pile in bending. In
addition, splices occurring in the upper 10 feet (3048 mm)
of the embedded portion of the pier or pile shall be capable
of resisting at allowable working stresses the moment and
shear that would result from an assumed eccentricity of the
pier or pile load of 3 inches (76 mm), or the pier or pile shall
be braced in accordance with Section 1808.2.5 to other piers
or piles that do not have splices in the upper 10 feet (3048
mm) of embedment.
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Allowable pier or pile loads.

Determination of allowable loads. The
allowable axial and lateral loads on piers or piles shall be
determined by an approved formula, load tests or method
of analysis.

Driving criteria. The allowable compressive
load on any pile where determined by the application of
an approved driving formula shall not exceed 40 tons
(356 kN). For allowable loads above 40 tons (356 kN),
the wave equation method of analysis shall be used to
estimate pile driveability of both driving stresses and net
displacement per blow at the ultimate load. Allowable
loads shall be verified by load tests in accordance with
Section 1808.2.8.3. The formula or wave equation load
shall be determined for gravity-drop or power-actuated
hammers and the hammer energy used shall be the maximum
consistent with the size, strength and weight of the
driven piles. The use of a follower is permitted only with
the approval of the building official. The introduction of
fresh hammer cushion or pile cushion material just prior
to final penetration is not permitted.

Load tests. Where design compressive loads
per pier or pile are greater than those permitted by Section
1808.2.10 or where the design load for any pier or
pile foundation is in doubt, control test piers or piles shall
be tested in accordance with ASTM D 1143 or ASTM D
4945. At least one pier or pile shall be test loaded in each
area of uniform subsoil conditions. Where required by
the building official, additional piers or piles shall be
load tested where necessary to establish the safe design
capacity. The resulting allowable loads shall not be more
than one-half of the ultimate axial load capacity of the
test pier or pile as assessed by one of the published methods
listed in Section 1808.2.8.3.1 with consideration for
the test type, duration and subsoil. The ultimate axial
load capacity shall be determined by a registered design
professional with consideration given to tolerable total
and differential settlements at design load in accordance
with Section 1808.2.12. In subsequent installation of the
balance of foundation piles, all piles shall be deemed to
have a supporting capacity equal to the control pile
where such piles are of the same type, size and relative
length as the test pile; are installed using the same or
comparable methods and equipment as the test pile; are
installed in similar subsoil conditions as the test pile;
and, for driven piles, where the rate of penetration (e.g.,
net displacement per blow) of such piles is equal to or
less than that of the test pile driven with the same hammer
through a comparable driving distance.

Load test evaluation. It shall be permitted
to evaluate pile load tests with any of the following
methods:
1. Davisson Offset Limit.
2. Brinch-Hansen 90% Criterion.
3. Butler-Hoy Criterion.
4. Other methods approved by the building official.

Allowable frictional resistance. The
assumed frictional resistance developed by any pier or
uncased cast-in-place pile shall not exceed one-sixth of
the bearing value of the soil material at minimum depth
as set forth in Table 1804.2, up to a maximum of 500 psf
(24 kPa), unless a greater value is allowed by the building
official after a soil investigation, as specified in Section
1802, is submitted or a greater value is substantiated by a
load test in accordance with Section 1808.2.8.3. Frictional
resistance and bearing resistance shall not be
assumed to act simultaneously unless recommended by a
soil investigation as specified in Section 1802.

Uplift capacity. Where required by the
design, the uplift capacity of a single pier or pile shall be
determined by an approved method of analysis based on
a minimum factor of safety of three or by load tests conducted
in accordance with ASTM D 3689. The maximum
allowable uplift load shall not exceed the ultimate
load capacity as determined in Section 1808.2.8.3
divided by a factor of safety of two. For pile groups subjected
to uplift, the allowable working uplift load for the
group shall be the lesser of:
1. The proposed individual pile uplift working load
times the number of piles in the group.
2. Two-thirds of the effective weight of the pile
group and the soil contained within a block defined
by the perimeter of the group and the length of the
pile.

Load-bearing capacity. Piers, individual
piles and groups of piles shall develop ultimate load
capacities of at least twice the design working loads in
the designated load-bearing layers. Analysis shall show
that no soil layer underlying the designated load-bearing
layers causes the load-bearing capacity safety factor to
be less than two.

Bent piers or piles. The load-bearing capacity
of piers or piles discovered to have a sharp or sweeping
bend shall be determined by an approved method of
analysis or by load testing a representative pier or pile.

Overloads on piers or piles. The maximum
compressive load on any pier or pile due to mislocation
shall not exceed 110 percent of the allowable design
load.

Lateral support.

General. Any soil other than fluid soil shall
be deemed to afford sufficient lateral support to the pier
or pile to prevent buckling and to permit the design of the
pier or pile in accordance with accepted engineering
practice and the applicable provisions of this code.

Unbraced piles. Piles standing unbraced in
air, water or in fluid soils shall be designed as columns in
accordance with the provisions of this code. Such piles
driven into firm ground can be considered fixed and laterally
supported at 5 feet (1524 mm) below the ground
surface and in soft material at 10 feet (3048 mm) below
the ground surface unless otherwise prescribed by the
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building official after a foundation investigation by an
approved agency.

Allowable lateral load. Where required by
the design, the lateral load capacity of a pier, a single pile
or a pile group shall be determined by an approved
method of analysis or by lateral load tests to at least twice
the proposed design working load. The resulting allowable
load shall not be more than one-half of that test load
that produces a gross lateralmovement of 1 inch (25 mm)
at the ground surface.

Use of higher allowable pier or pile stresses.
Allowable stresses greater than those specified for piers or
for each pile type in Sections 1809 and 1810 are permitted
where supporting data justifying such higher stresses is filed
with the building official. Such substantiating data shall
include:
1. A soils investigation in accordance with Section
1802.
2. Pier or pile load tests in accordance with Section
1808.2.8.3, regardless of the load supported by the
pier or pile.
The design and installation of the pier or pile foundation
shall be under the direct supervision of a registered design
professional knowledgeable in the field of soil mechanics
and pier or pile foundations who shall certify to the building
official that the piers or piles as installed satisfy the design
criteria.

Piles in subsiding areas. Where piles are
installed through subsiding fills or other subsiding strata
and derive support from underlying firmer materials, consideration
shall be given to the downward frictional forces
that may be imposed on the piles by the subsiding upper
strata.
Where the influence of subsiding fills is considered as
imposing loads on the pile, the allowable stresses specified
in this chapter are permitted to be increased where satisfactory
substantiating data are submitted.

Settlement analysis. The settlement of piers,
individual piles or groups of piles shall be estimated based
on approved methods of analysis. The predicted settlement
shall cause neither harmful distortion of, nor instability in,
the structure, nor cause any stresses to exceed allowable values.

Preexcavation. The use of jetting, augering or
other methods of preexcavation shall be subject to the
approval of the building official. Where permitted,
preexcavation shall be carried out in the same manner as
used for piers or piles subject to load tests and in such a manner
that will not impair the carrying capacity of the piers or
piles already in place or damage adjacent structures. Pile
tips shall be driven below the preexcavated depth until the
required resistance or penetration is obtained.

Installation sequence. Piles shall be installed in
such sequence as to avoid compacting the surrounding soil
to the extent that other piles cannot be installed properly,
and to prevent ground movements that are capable of damaging
adjacent structures.

Use of vibratory drivers.Vibratory drivers shall
only be used to install piles where the pile load capacity is
verified by load tests in accordance with Section 1808.2.8.3.
The installation of production piles shall be controlled
according to power consumption, rate of penetration or
other approved means that ensure pile capacities equal or
exceed those of the test piles.

Pile driveability. Pile cross sections shall be of
sufficient size and strength to withstand driving stresses
without damage to the pile, and to provide sufficient stiffness
to transmit the required driving forces.

Protection of pile materials. Where boring
records or site conditions indicate possible deleterious
action on pier or pile materials because of soil constituents,
changing water levels or other factors, the pier or pile materials
shall be adequately protected by materials, methods or
processes approved by the building official. Protective
materials shall be applied to the piles so as not to be rendered
ineffective by driving. The effectiveness of such protective
measures for the particular purpose shall have been thoroughly
established by satisfactory service records or other
evidence.

Use of existing piers or piles. Piers or piles left
in place where a structure has been demolished shall not be
used for the support of new construction unless satisfactory
evidence is submitted to the building official, which indicates
that the piers or piles are sound and meet the requirements
of this code. Such piers or piles shall be load tested or
redriven to verify their capacities. The design load applied
to such piers or piles shall be the lowest allowable load as
determined by tests or redriving data.

Heaved piles. Piles that have heaved during the
driving of adjacent piles shall be redriven as necessary to
develop the required capacity and penetration, or the capacity
of the pile shall be verified by load tests in accordance
with Section 1808.2.8.3.

Identification. Pier or pile materials shall be
identified for conformity to the specified grade with this
identity maintained continuously from the point of manufacture
to the point of installation or shall be tested by an
approved agency to determine conformity to the specified
grade. The approved agency shall furnish an affidavit of
compliance to the building official.

Pier or pile location plan. A plan showing the
location and designation of piers or piles by an identification
system shall be filed with the building official prior to
installation of such piers or piles. Detailed records for piers
or individual piles shall bear an identification corresponding
to that shown on the plan.

Special inspection. Special inspections in accordance
with Sections 1704.8 and 1704.9 shall be provided
for piles and piers, respectively.
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Seismic design of piers or piles.

Seismic Design Category C. Where a
structure is assigned to Seismic Design Category C in
accordance with Section 1613, the following shall apply.
Individual pile caps, piers or piles shall be interconnected
by ties. Ties shall be capable of carrying, in tension
and compression, a force equal to the product of the
larger pile cap or column load times the seismic coefficient,
SDS, divided by 10 unless it can be demonstrated
that equivalent restraint is provided by reinforced concrete
beams within slabs on grade, reinforced concrete
slabs on grade, confinement by competent rock, hard
cohesive soils or very dense granular soils.
Exception: Piers supporting foundation walls, isolated
interior posts detailed so the pier is not subject to
lateral loads, lightly loaded exterior decks and patios
of Group R-3 and U occupancies not exceeding two
stories of light-frame construction, are not subject to
interconnection if it can be shown the soils are of adequate
stiffness, subject to the approval of the building
official.

Connection to pile cap. Concrete piles
and concrete-filled steel pipe piles shall be connected
to the pile cap by embedding the pile reinforcement or
field-placed dowels anchored in the concrete pile in
the pile cap for a distance equal to the development
length. For deformed bars, the development length is
the full development length for compression or tension,
in the case of uplift, without reduction in length
for excess area. Alternative measures for laterally
confining concrete and maintaining toughness and
ductile-like behavior at the top of the pile will be permitted
provided the design is such that any hinging
occurs in the confined region.
Ends of hoops, spirals and ties shall be terminated
with seismic hooks, as defined in Section 21.1 of ACI
318, turned into the confined concrete core. The minimum
transverse steel ratio for confinement shall not
be less than one-half of that required for columns.
For resistance to uplift forces, anchorage of steel
pipe (round HSS sections), concrete-filled steel pipe
or H-piles to the pile cap shall be made by means other
than concrete bond to the bare steel section.
Exception: Anchorage of concrete-filled steel
pipe piles is permitted to be accomplished using
deformed bars developed into the concrete portion
of the pile.
Splices of pile segments shall develop the full
strength of the pile, but the splice need not develop the
nominal strength of the pile in tension, shear and
bending when it has been designed to resist axial and
shear forces and moments from the load combinations
of Section 1605.4.

Design details. Pier or pile moments,
shears and lateral deflections used for design shall be
established considering the nonlinear interaction of
the shaft and soil, as recommended by a registered
design professional. Where the ratio of the depth of
embedment of the pile-to-pile diameter or width is
less than or equal to six, the pile may be assumed to be
rigid.
Pile group effects from soil on lateral pile nominal
strength shall be included where pile center-to-center
spacing in the direction of lateral force is less than
eight pile diameters. Pile group effects on vertical
nominal strength shall be included where pile center-
to-center spacing is less than three pile diameters.
The pile uplift soil nominal strength shall be taken as
the pile uplift strength as limited by the frictional
force developed between the soil and the pile.
Where a minimum length for reinforcement or the
extent of closely spaced confinement reinforcement is
specified at the top of the pier or pile, provisions shall
be made so that those specified lengths or extents are
maintained after pier or pile cutoff.

Seismic Design Category D, Eor F. Where
a structure is assigned to Seismic Design Category D, E
or F in accordance with Section 1613, the requirements
for Seismic Design Category C given in Section
1808.2.23.1 shall be met, in addition to the following.
Provisions of ACI 318, Section 21.10.4, shall apply
when not in conflict with the provisions of Sections 1808
through 1812. Concrete shall have a specified compressive
strength of not less than 3,000 psi (20.68 MPa) at 28
days.
Exceptions:
1. Group R or U occupancies of light-framed construction
and two stories or less in height are
permitted to use concrete with a specified compressive
strength of not less than 2,500 psi (17.2
MPa) at 28 days.
2. Detached one- and two-family dwellings of
light-frame construction and two stories or less
in height are not required to comply with the
provisions of ACI 318, Section 21.10.4.
3. Section 21.10.4.4( a) of ACI 318 need not apply
to concrete piles.

Design details for piers, piles and
grade beams. Piers or piles shall be designed and
constructed to withstand maximum imposed curvatures
from earthquake ground motions and structure
response. Curvatures shall include free-field soil
strains modified for soil-pile-structure interaction
coupled with pier or pile deformations induced by lateral
pier or pile resistance to structure seismic forces.
Concrete piers or piles on Site Class E or F sites, as
determined in Section 1613.5.2, shall be designed and
detailed in accordance with Sections 21.4.4.1,
21.4.4.2 and 21.4.4.3 of ACI 318 within seven pile
diameters of the pile cap and the interfaces of soft to
medium stiff clay or liquefiable strata. For precast
prestressed concrete piles, detailing provisions as
given in Sections 1809.2.3.2.1 and 1809.2.3.2.2 shall
apply. Grade beams shall be designed as beams in
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accordance with ACI 318, Chapter 21. When grade
beams have the capacity to resist the forces from the
load combinations in Section 1605.4, they need not
conform to ACI 318, Chapter 21.

Connection to pile cap. For piles
required to resist uplift forces or provide rotational
restraint, design of anchorage of piles into the pile cap
shall be provided considering the combined effect of
axial forces due to uplift and bending moments due to
fixity to the pile cap. Anchorage shall develop a minimum
of 25 percent of the strength of the pile in tension.
Anchorage into the pile cap shall be capable of
developing the following:
1. In the case of uplift, the lesser of the nominal
tensile strength of the longitudinal reinforcement
in a concrete pile, or the nominal tensile
strength of a steel pile, or the pile uplift soil
nominal strength factored by 1.3 or the axial
tension force resulting from the load combinations
of Section 1605.4.
2. In the case of rotational restraint, the lesser of
the axial and shear forces, and moments resulting
from the load combinations of Section
1605.4 or development of the full axial, bending
and shear nominal strength of the pile.

Flexural strength. Where the vertical
lateral-force-resisting elements are columns, the
grade beam or pile cap flexural strengths shall exceed
the column flexural strength.
The connection between batter piles and grade
beams or pile caps shall be designed to resist the nominal
strength of the pile acting as a short column. Batter
piles and their connection shall be capable of
resisting forces and moments from the load combinations
of Section 1605.4.

International Building Code 1808.2.1

Design. Piles are permitted to be designed in
accordance with provisions for piers in Section 1808 and
Sections 1812.3 through 1812.10 where either of the following
conditions exists, subject to the approval of the
building official:
1. Group R-3 and U occupancies not exceeding two stories
of light-frame construction, or
2. Where the surrounding foundation materials furnish
adequate lateral support for the pile.

International Building Code 1808.2.10

Use of higher allowable pier or pile stresses.
Allowable stresses greater than those specified for piers or
for each pile type in Sections 1809 and 1810 are permitted
where supporting data justifying such higher stresses is filed
with the building official. Such substantiating data shall
include:
1. A soils investigation in accordance with Section
1802.
2. Pier or pile load tests in accordance with Section
1808.2.8.3, regardless of the load supported by the
pier or pile.
The design and installation of the pier or pile foundation
shall be under the direct supervision of a registered design
professional knowledgeable in the field of soil mechanics
and pier or pile foundations who shall certify to the building
official that the piers or piles as installed satisfy the design
criteria.

International Building Code 1808.2.11

Piles in subsiding areas. Where piles are
installed through subsiding fills or other subsiding strata
and derive support from underlying firmer materials, consideration
shall be given to the downward frictional forces
that may be imposed on the piles by the subsiding upper
strata.
Where the influence of subsiding fills is considered as
imposing loads on the pile, the allowable stresses specified
in this chapter are permitted to be increased where satisfactory
substantiating data are submitted.

International Building Code 1808.2.12

Settlement analysis. The settlement of piers,
individual piles or groups of piles shall be estimated based
on approved methods of analysis. The predicted settlement
shall cause neither harmful distortion of, nor instability in,
the structure, nor cause any stresses to exceed allowable values.

International Building Code 1808.2.13

Preexcavation. The use of jetting, augering or
other methods of preexcavation shall be subject to the
approval of the building official. Where permitted,
preexcavation shall be carried out in the same manner as
used for piers or piles subject to load tests and in such a manner
that will not impair the carrying capacity of the piers or
piles already in place or damage adjacent structures. Pile
tips shall be driven below the preexcavated depth until the
required resistance or penetration is obtained.

International Building Code 1808.2.14

Installation sequence. Piles shall be installed in
such sequence as to avoid compacting the surrounding soil
to the extent that other piles cannot be installed properly,
and to prevent ground movements that are capable of damaging
adjacent structures.

International Building Code 1808.2.15

Use of vibratory drivers.Vibratory drivers shall
only be used to install piles where the pile load capacity is
verified by load tests in accordance with Section 1808.2.8.3.
The installation of production piles shall be controlled
according to power consumption, rate of penetration or
other approved means that ensure pile capacities equal or
exceed those of the test piles.

International Building Code 1808.2.16

Pile driveability. Pile cross sections shall be of
sufficient size and strength to withstand driving stresses
without damage to the pile, and to provide sufficient stiffness
to transmit the required driving forces.

International Building Code 1808.2.17

Protection of pile materials. Where boring
records or site conditions indicate possible deleterious
action on pier or pile materials because of soil constituents,
changing water levels or other factors, the pier or pile materials
shall be adequately protected by materials, methods or
processes approved by the building official. Protective
materials shall be applied to the piles so as not to be rendered
ineffective by driving. The effectiveness of such protective
measures for the particular purpose shall have been thoroughly
established by satisfactory service records or other
evidence.

International Building Code 1808.2.18

Use of existing piers or piles. Piers or piles left
in place where a structure has been demolished shall not be
used for the support of new construction unless satisfactory
evidence is submitted to the building official, which indicates
that the piers or piles are sound and meet the requirements
of this code. Such piers or piles shall be load tested or
redriven to verify their capacities. The design load applied
to such piers or piles shall be the lowest allowable load as
determined by tests or redriving data.

International Building Code 1808.2.19

Heaved piles. Piles that have heaved during the
driving of adjacent piles shall be redriven as necessary to
develop the required capacity and penetration, or the capacity
of the pile shall be verified by load tests in accordance
with Section 1808.2.8.3.

International Building Code 1808.2.2

General. Pier and pile foundations shall be
designed and installed on the basis of a foundation investigation
as defined in Section 1802, unless sufficient data
upon which to base the design and installation is available.
The investigation and report provisions of Section 1802
shall be expanded to include, but not be limited to, the following:
1. Recommended pier or pile types and installed capacities.
2. Recommended center-to-center spacing of piers or
piles.
3. Driving criteria.
4. Installation procedures.
5. Field inspection and reporting procedures (to include
procedures for verification of the installed bearing
capacity where required).
6. Pier or pile load test requirements.
7. Durability of pier or pile materials.
8. Designation of bearing stratum or strata.
9. Reductions for group action, where necessary.

International Building Code 1808.2.20

Identification. Pier or pile materials shall be
identified for conformity to the specified grade with this
identity maintained continuously from the point of manufacture
to the point of installation or shall be tested by an
approved agency to determine conformity to the specified
grade. The approved agency shall furnish an affidavit of
compliance to the building official.

International Building Code 1808.2.21

Pier or pile location plan. A plan showing the
location and designation of piers or piles by an identification
system shall be filed with the building official prior to
installation of such piers or piles. Detailed records for piers
or individual piles shall bear an identification corresponding
to that shown on the plan.

International Building Code 1808.2.22

Special inspection. Special inspections in accordance
with Sections 1704.8 and 1704.9 shall be provided
for piles and piers, respectively.
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International Building Code 1808.2.23

Seismic design of piers or piles.

Seismic Design Category C. Where a
structure is assigned to Seismic Design Category C in
accordance with Section 1613, the following shall apply.
Individual pile caps, piers or piles shall be interconnected
by ties. Ties shall be capable of carrying, in tension
and compression, a force equal to the product of the
larger pile cap or column load times the seismic coefficient,
SDS, divided by 10 unless it can be demonstrated
that equivalent restraint is provided by reinforced concrete
beams within slabs on grade, reinforced concrete
slabs on grade, confinement by competent rock, hard
cohesive soils or very dense granular soils.
Exception: Piers supporting foundation walls, isolated
interior posts detailed so the pier is not subject to
lateral loads, lightly loaded exterior decks and patios
of Group R-3 and U occupancies not exceeding two
stories of light-frame construction, are not subject to
interconnection if it can be shown the soils are of adequate
stiffness, subject to the approval of the building
official.

Connection to pile cap. Concrete piles
and concrete-filled steel pipe piles shall be connected
to the pile cap by embedding the pile reinforcement or
field-placed dowels anchored in the concrete pile in
the pile cap for a distance equal to the development
length. For deformed bars, the development length is
the full development length for compression or tension,
in the case of uplift, without reduction in length
for excess area. Alternative measures for laterally
confining concrete and maintaining toughness and
ductile-like behavior at the top of the pile will be permitted
provided the design is such that any hinging
occurs in the confined region.
Ends of hoops, spirals and ties shall be terminated
with seismic hooks, as defined in Section 21.1 of ACI
318, turned into the confined concrete core. The minimum
transverse steel ratio for confinement shall not
be less than one-half of that required for columns.
For resistance to uplift forces, anchorage of steel
pipe (round HSS sections), concrete-filled steel pipe
or H-piles to the pile cap shall be made by means other
than concrete bond to the bare steel section.
Exception: Anchorage of concrete-filled steel
pipe piles is permitted to be accomplished using
deformed bars developed into the concrete portion
of the pile.
Splices of pile segments shall develop the full
strength of the pile, but the splice need not develop the
nominal strength of the pile in tension, shear and
bending when it has been designed to resist axial and
shear forces and moments from the load combinations
of Section 1605.4.

Design details. Pier or pile moments,
shears and lateral deflections used for design shall be
established considering the nonlinear interaction of
the shaft and soil, as recommended by a registered
design professional. Where the ratio of the depth of
embedment of the pile-to-pile diameter or width is
less than or equal to six, the pile may be assumed to be
rigid.
Pile group effects from soil on lateral pile nominal
strength shall be included where pile center-to-center
spacing in the direction of lateral force is less than
eight pile diameters. Pile group effects on vertical
nominal strength shall be included where pile center-
to-center spacing is less than three pile diameters.
The pile uplift soil nominal strength shall be taken as
the pile uplift strength as limited by the frictional
force developed between the soil and the pile.
Where a minimum length for reinforcement or the
extent of closely spaced confinement reinforcement is
specified at the top of the pier or pile, provisions shall
be made so that those specified lengths or extents are
maintained after pier or pile cutoff.

Seismic Design Category D, Eor F. Where
a structure is assigned to Seismic Design Category D, E
or F in accordance with Section 1613, the requirements
for Seismic Design Category C given in Section
1808.2.23.1 shall be met, in addition to the following.
Provisions of ACI 318, Section 21.10.4, shall apply
when not in conflict with the provisions of Sections 1808
through 1812. Concrete shall have a specified compressive
strength of not less than 3,000 psi (20.68 MPa) at 28
days.
Exceptions:
1. Group R or U occupancies of light-framed construction
and two stories or less in height are
permitted to use concrete with a specified compressive
strength of not less than 2,500 psi (17.2
MPa) at 28 days.
2. Detached one- and two-family dwellings of
light-frame construction and two stories or less
in height are not required to comply with the
provisions of ACI 318, Section 21.10.4.
3. Section 21.10.4.4( a) of ACI 318 need not apply
to concrete piles.

Design details for piers, piles and
grade beams. Piers or piles shall be designed and
constructed to withstand maximum imposed curvatures
from earthquake ground motions and structure
response. Curvatures shall include free-field soil
strains modified for soil-pile-structure interaction
coupled with pier or pile deformations induced by lateral
pier or pile resistance to structure seismic forces.
Concrete piers or piles on Site Class E or F sites, as
determined in Section 1613.5.2, shall be designed and
detailed in accordance with Sections 21.4.4.1,
21.4.4.2 and 21.4.4.3 of ACI 318 within seven pile
diameters of the pile cap and the interfaces of soft to
medium stiff clay or liquefiable strata. For precast
prestressed concrete piles, detailing provisions as
given in Sections 1809.2.3.2.1 and 1809.2.3.2.2 shall
apply. Grade beams shall be designed as beams in
362 2006 INTERNATIONAL BUILDING CODE
SOILS AND FOUNDATIONS
accordance with ACI 318, Chapter 21. When grade
beams have the capacity to resist the forces from the
load combinations in Section 1605.4, they need not
conform to ACI 318, Chapter 21.

Connection to pile cap. For piles
required to resist uplift forces or provide rotational
restraint, design of anchorage of piles into the pile cap
shall be provided considering the combined effect of
axial forces due to uplift and bending moments due to
fixity to the pile cap. Anchorage shall develop a minimum
of 25 percent of the strength of the pile in tension.
Anchorage into the pile cap shall be capable of
developing the following:
1. In the case of uplift, the lesser of the nominal
tensile strength of the longitudinal reinforcement
in a concrete pile, or the nominal tensile
strength of a steel pile, or the pile uplift soil
nominal strength factored by 1.3 or the axial
tension force resulting from the load combinations
of Section 1605.4.
2. In the case of rotational restraint, the lesser of
the axial and shear forces, and moments resulting
from the load combinations of Section
1605.4 or development of the full axial, bending
and shear nominal strength of the pile.

Flexural strength. Where the vertical
lateral-force-resisting elements are columns, the
grade beam or pile cap flexural strengths shall exceed
the column flexural strength.
The connection between batter piles and grade
beams or pile caps shall be designed to resist the nominal
strength of the pile acting as a short column. Batter
piles and their connection shall be capable of
resisting forces and moments from the load combinations
of Section 1605.4.

International Building Code 1808.2.23.1

Seismic Design Category C. Where a
structure is assigned to Seismic Design Category C in
accordance with Section 1613, the following shall apply.
Individual pile caps, piers or piles shall be interconnected
by ties. Ties shall be capable of carrying, in tension
and compression, a force equal to the product of the
larger pile cap or column load times the seismic coefficient,
SDS, divided by 10 unless it can be demonstrated
that equivalent restraint is provided by reinforced concrete
beams within slabs on grade, reinforced concrete
slabs on grade, confinement by competent rock, hard
cohesive soils or very dense granular soils.
Exception: Piers supporting foundation walls, isolated
interior posts detailed so the pier is not subject to
lateral loads, lightly loaded exterior decks and patios
of Group R-3 and U occupancies not exceeding two
stories of light-frame construction, are not subject to
interconnection if it can be shown the soils are of adequate
stiffness, subject to the approval of the building
official.

Connection to pile cap. Concrete piles
and concrete-filled steel pipe piles shall be connected
to the pile cap by embedding the pile reinforcement or
field-placed dowels anchored in the concrete pile in
the pile cap for a distance equal to the development
length. For deformed bars, the development length is
the full development length for compression or tension,
in the case of uplift, without reduction in length
for excess area. Alternative measures for laterally
confining concrete and maintaining toughness and
ductile-like behavior at the top of the pile will be permitted
provided the design is such that any hinging
occurs in the confined region.
Ends of hoops, spirals and ties shall be terminated
with seismic hooks, as defined in Section 21.1 of ACI
318, turned into the confined concrete core. The minimum
transverse steel ratio for confinement shall not
be less than one-half of that required for columns.
For resistance to uplift forces, anchorage of steel
pipe (round HSS sections), concrete-filled steel pipe
or H-piles to the pile cap shall be made by means other
than concrete bond to the bare steel section.
Exception: Anchorage of concrete-filled steel
pipe piles is permitted to be accomplished using
deformed bars developed into the concrete portion
of the pile.
Splices of pile segments shall develop the full
strength of the pile, but the splice need not develop the
nominal strength of the pile in tension, shear and
bending when it has been designed to resist axial and
shear forces and moments from the load combinations
of Section 1605.4.

Design details. Pier or pile moments,
shears and lateral deflections used for design shall be
established considering the nonlinear interaction of
the shaft and soil, as recommended by a registered
design professional. Where the ratio of the depth of
embedment of the pile-to-pile diameter or width is
less than or equal to six, the pile may be assumed to be
rigid.
Pile group effects from soil on lateral pile nominal
strength shall be included where pile center-to-center
spacing in the direction of lateral force is less than
eight pile diameters. Pile group effects on vertical
nominal strength shall be included where pile center-
to-center spacing is less than three pile diameters.
The pile uplift soil nominal strength shall be taken as
the pile uplift strength as limited by the frictional
force developed between the soil and the pile.
Where a minimum length for reinforcement or the
extent of closely spaced confinement reinforcement is
specified at the top of the pier or pile, provisions shall
be made so that those specified lengths or extents are
maintained after pier or pile cutoff.

International Building Code 1808.2.23.1.1

Connection to pile cap. Concrete piles
and concrete-filled steel pipe piles shall be connected
to the pile cap by embedding the pile reinforcement or
field-placed dowels anchored in the concrete pile in
the pile cap for a distance equal to the development
length. For deformed bars, the development length is
the full development length for compression or tension,
in the case of uplift, without reduction in length
for excess area. Alternative measures for laterally
confining concrete and maintaining toughness and
ductile-like behavior at the top of the pile will be permitted
provided the design is such that any hinging
occurs in the confined region.
Ends of hoops, spirals and ties shall be terminated
with seismic hooks, as defined in Section 21.1 of ACI
318, turned into the confined concrete core. The minimum
transverse steel ratio for confinement shall not
be less than one-half of that required for columns.
For resistance to uplift forces, anchorage of steel
pipe (round HSS sections), concrete-filled steel pipe
or H-piles to the pile cap shall be made by means other
than concrete bond to the bare steel section.
Exception: Anchorage of concrete-filled steel
pipe piles is permitted to be accomplished using
deformed bars developed into the concrete portion
of the pile.
Splices of pile segments shall develop the full
strength of the pile, but the splice need not develop the
nominal strength of the pile in tension, shear and
bending when it has been designed to resist axial and
shear forces and moments from the load combinations
of Section 1605.4.

International Building Code 1808.2.23.1.2

Design details. Pier or pile moments,
shears and lateral deflections used for design shall be
established considering the nonlinear interaction of
the shaft and soil, as recommended by a registered
design professional. Where the ratio of the depth of
embedment of the pile-to-pile diameter or width is
less than or equal to six, the pile may be assumed to be
rigid.
Pile group effects from soil on lateral pile nominal
strength shall be included where pile center-to-center
spacing in the direction of lateral force is less than
eight pile diameters. Pile group effects on vertical
nominal strength shall be included where pile center-
to-center spacing is less than three pile diameters.
The pile uplift soil nominal strength shall be taken as
the pile uplift strength as limited by the frictional
force developed between the soil and the pile.
Where a minimum length for reinforcement or the
extent of closely spaced confinement reinforcement is
specified at the top of the pier or pile, provisions shall
be made so that those specified lengths or extents are
maintained after pier or pile cutoff.

International Building Code 1808.2.23.2

Seismic Design Category D, Eor F. Where
a structure is assigned to Seismic Design Category D, E
or F in accordance with Section 1613, the requirements
for Seismic Design Category C given in Section
1808.2.23.1 shall be met, in addition to the following.
Provisions of ACI 318, Section 21.10.4, shall apply
when not in conflict with the provisions of Sections 1808
through 1812. Concrete shall have a specified compressive
strength of not less than 3,000 psi (20.68 MPa) at 28
days.
Exceptions:
1. Group R or U occupancies of light-framed construction
and two stories or less in height are
permitted to use concrete with a specified compressive
strength of not less than 2,500 psi (17.2
MPa) at 28 days.
2. Detached one- and two-family dwellings of
light-frame construction and two stories or less
in height are not required to comply with the
provisions of ACI 318, Section 21.10.4.
3. Section 21.10.4.4( a) of ACI 318 need not apply
to concrete piles.

Design details for piers, piles and
grade beams. Piers or piles shall be designed and
constructed to withstand maximum imposed curvatures
from earthquake ground motions and structure
response. Curvatures shall include free-field soil
strains modified for soil-pile-structure interaction
coupled with pier or pile deformations induced by lateral
pier or pile resistance to structure seismic forces.
Concrete piers or piles on Site Class E or F sites, as
determined in Section 1613.5.2, shall be designed and
detailed in accordance with Sections 21.4.4.1,
21.4.4.2 and 21.4.4.3 of ACI 318 within seven pile
diameters of the pile cap and the interfaces of soft to
medium stiff clay or liquefiable strata. For precast
prestressed concrete piles, detailing provisions as
given in Sections 1809.2.3.2.1 and 1809.2.3.2.2 shall
apply. Grade beams shall be designed as beams in
362 2006 INTERNATIONAL BUILDING CODE
SOILS AND FOUNDATIONS
accordance with ACI 318, Chapter 21. When grade
beams have the capacity to resist the forces from the
load combinations in Section 1605.4, they need not
conform to ACI 318, Chapter 21.

Connection to pile cap. For piles
required to resist uplift forces or provide rotational
restraint, design of anchorage of piles into the pile cap
shall be provided considering the combined effect of
axial forces due to uplift and bending moments due to
fixity to the pile cap. Anchorage shall develop a minimum
of 25 percent of the strength of the pile in tension.
Anchorage into the pile cap shall be capable of
developing the following:
1. In the case of uplift, the lesser of the nominal
tensile strength of the longitudinal reinforcement
in a concrete pile, or the nominal tensile
strength of a steel pile, or the pile uplift soil
nominal strength factored by 1.3 or the axial
tension force resulting from the load combinations
of Section 1605.4.
2. In the case of rotational restraint, the lesser of
the axial and shear forces, and moments resulting
from the load combinations of Section
1605.4 or development of the full axial, bending
and shear nominal strength of the pile.

Flexural strength. Where the vertical
lateral-force-resisting elements are columns, the
grade beam or pile cap flexural strengths shall exceed
the column flexural strength.
The connection between batter piles and grade
beams or pile caps shall be designed to resist the nominal
strength of the pile acting as a short column. Batter
piles and their connection shall be capable of
resisting forces and moments from the load combinations
of Section 1605.4.

International Building Code 1808.2.23.2.1

Design details for piers, piles and
grade beams. Piers or piles shall be designed and
constructed to withstand maximum imposed curvatures
from earthquake ground motions and structure
response. Curvatures shall include free-field soil
strains modified for soil-pile-structure interaction
coupled with pier or pile deformations induced by lateral
pier or pile resistance to structure seismic forces.
Concrete piers or piles on Site Class E or F sites, as
determined in Section 1613.5.2, shall be designed and
detailed in accordance with Sections 21.4.4.1,
21.4.4.2 and 21.4.4.3 of ACI 318 within seven pile
diameters of the pile cap and the interfaces of soft to
medium stiff clay or liquefiable strata. For precast
prestressed concrete piles, detailing provisions as
given in Sections 1809.2.3.2.1 and 1809.2.3.2.2 shall
apply. Grade beams shall be designed as beams in
362 2006 INTERNATIONAL BUILDING CODE
SOILS AND FOUNDATIONS
accordance with ACI 318, Chapter 21. When grade
beams have the capacity to resist the forces from the
load combinations in Section 1605.4, they need not
conform to ACI 318, Chapter 21.

International Building Code 1808.2.23.2.2

Connection to pile cap. For piles
required to resist uplift forces or provide rotational
restraint, design of anchorage of piles into the pile cap
shall be provided considering the combined effect of
axial forces due to uplift and bending moments due to
fixity to the pile cap. Anchorage shall develop a minimum
of 25 percent of the strength of the pile in tension.
Anchorage into the pile cap shall be capable of
developing the following:
1. In the case of uplift, the lesser of the nominal
tensile strength of the longitudinal reinforcement
in a concrete pile, or the nominal tensile
strength of a steel pile, or the pile uplift soil
nominal strength factored by 1.3 or the axial
tension force resulting from the load combinations
of Section 1605.4.
2. In the case of rotational restraint, the lesser of
the axial and shear forces, and moments resulting
from the load combinations of Section
1605.4 or development of the full axial, bending
and shear nominal strength of the pile.

International Building Code 1808.2.23.2.3

Flexural strength. Where the vertical
lateral-force-resisting elements are columns, the
grade beam or pile cap flexural strengths shall exceed
the column flexural strength.
The connection between batter piles and grade
beams or pile caps shall be designed to resist the nominal
strength of the pile acting as a short column. Batter
piles and their connection shall be capable of
resisting forces and moments from the load combinations
of Section 1605.4.

International Building Code 1808.2.3

Special types of piles. The use of types of piles not
specifically mentioned herein is permitted, subject to the
approval of the building official, upon the submission of
acceptable test data, calculations and other information
relating to the structural properties and load capacity of such
piles. The allowable stresses shall not in any case exceed the
limitations specified herein.

International Building Code 1808.2.4

Pile caps. Pile caps shall be of reinforced concrete,
and shall include all elements to which piles are connected,
including grade beams and mats. The soil immediately
below the pile cap shall not be considered as carrying any
vertical load. The tops of piles shall be embedded not less
than 3 inches (76 mm) into pile caps and the caps shall
extend at least 4 inches (102 mm) beyond the edges of piles.
The tops of piles shall be cut back to sound material before
capping.

International Building Code 1808.2.5

Stability. Piers or piles shall be braced to provide
lateral stability in all directions. Three or more piles connected
by a rigid cap shall be considered braced, provided
that the piles are located in radial directions from the centroid
of the group not less than 60 degrees (1 rad) apart. A
two-pile group in a rigid cap shall be considered to be
braced along the axis connecting the two piles. Methods
used to brace piers or piles shall be subject to the approval of
the building official.
Piles supportingwalls shall be driven alternately in lines
spaced at least 1 foot (305 mm) apart and located symmetrically
under the center of gravity of the wall load carried,
unless effective measures are taken to provide for eccentricity
and lateral forces, or the wall piles are adequately
braced to provide for lateral stability. A single row of piles
without lateral bracing is permitted for one- and two-family
dwellings and lightweight construction not exceeding
two stories or 35 feet (10 668 mm) in height, provided the
centers of the piles are locatedwithin thewidth of the foundation
wall.

International Building Code 1808.2.6

Structural integrity. Piers or piles shall be
installed in such a manner and sequence as to prevent distortion
or damage that may adversely affect the structural
integrity of piles being installed or already in place.

International Building Code 1808.2.7

Splices. Splices shall be constructed so as to provide
and maintain true alignment and position of the component
parts of the pier or pile during installation and
subsequent thereto and shall be of adequate strength to
transmit the vertical and lateral loads and moments occurring
at the location of the splice during driving and under
service loading. Splices shall develop not less than 50 percent
of the least capacity of the pier or pile in bending. In
addition, splices occurring in the upper 10 feet (3048 mm)
of the embedded portion of the pier or pile shall be capable
of resisting at allowable working stresses the moment and
shear that would result from an assumed eccentricity of the
pier or pile load of 3 inches (76 mm), or the pier or pile shall
be braced in accordance with Section 1808.2.5 to other piers
or piles that do not have splices in the upper 10 feet (3048
mm) of embedment.
2006 INTERNATIONAL BUILDING CODE 359
SOILS AND FOUNDATIONS

International Building Code 1808.2.8

Allowable pier or pile loads.

Determination of allowable loads. The
allowable axial and lateral loads on piers or piles shall be
determined by an approved formula, load tests or method
of analysis.

Driving criteria. The allowable compressive
load on any pile where determined by the application of
an approved driving formula shall not exceed 40 tons
(356 kN). For allowable loads above 40 tons (356 kN),
the wave equation method of analysis shall be used to
estimate pile driveability of both driving stresses and net
displacement per blow at the ultimate load. Allowable
loads shall be verified by load tests in accordance with
Section 1808.2.8.3. The formula or wave equation load
shall be determined for gravity-drop or power-actuated
hammers and the hammer energy used shall be the maximum
consistent with the size, strength and weight of the
driven piles. The use of a follower is permitted only with
the approval of the building official. The introduction of
fresh hammer cushion or pile cushion material just prior
to final penetration is not permitted.

Load tests. Where design compressive loads
per pier or pile are greater than those permitted by Section
1808.2.10 or where the design load for any pier or
pile foundation is in doubt, control test piers or piles shall
be tested in accordance with ASTM D 1143 or ASTM D
4945. At least one pier or pile shall be test loaded in each
area of uniform subsoil conditions. Where required by
the building official, additional piers or piles shall be
load tested where necessary to establish the safe design
capacity. The resulting allowable loads shall not be more
than one-half of the ultimate axial load capacity of the
test pier or pile as assessed by one of the published methods
listed in Section 1808.2.8.3.1 with consideration for
the test type, duration and subsoil. The ultimate axial
load capacity shall be determined by a registered design
professional with consideration given to tolerable total
and differential settlements at design load in accordance
with Section 1808.2.12. In subsequent installation of the
balance of foundation piles, all piles shall be deemed to
have a supporting capacity equal to the control pile
where such piles are of the same type, size and relative
length as the test pile; are installed using the same or
comparable methods and equipment as the test pile; are
installed in similar subsoil conditions as the test pile;
and, for driven piles, where the rate of penetration (e.g.,
net displacement per blow) of such piles is equal to or
less than that of the test pile driven with the same hammer
through a comparable driving distance.

Load test evaluation. It shall be permitted
to evaluate pile load tests with any of the following
methods:
1. Davisson Offset Limit.
2. Brinch-Hansen 90% Criterion.
3. Butler-Hoy Criterion.
4. Other methods approved by the building official.

Allowable frictional resistance. The
assumed frictional resistance developed by any pier or
uncased cast-in-place pile shall not exceed one-sixth of
the bearing value of the soil material at minimum depth
as set forth in Table 1804.2, up to a maximum of 500 psf
(24 kPa), unless a greater value is allowed by the building
official after a soil investigation, as specified in Section
1802, is submitted or a greater value is substantiated by a
load test in accordance with Section 1808.2.8.3. Frictional
resistance and bearing resistance shall not be
assumed to act simultaneously unless recommended by a
soil investigation as specified in Section 1802.

Uplift capacity. Where required by the
design, the uplift capacity of a single pier or pile shall be
determined by an approved method of analysis based on
a minimum factor of safety of three or by load tests conducted
in accordance with ASTM D 3689. The maximum
allowable uplift load shall not exceed the ultimate
load capacity as determined in Section 1808.2.8.3
divided by a factor of safety of two. For pile groups subjected
to uplift, the allowable working uplift load for the
group shall be the lesser of:
1. The proposed individual pile uplift working load
times the number of piles in the group.
2. Two-thirds of the effective weight of the pile
group and the soil contained within a block defined
by the perimeter of the group and the length of the
pile.

Load-bearing capacity. Piers, individual
piles and groups of piles shall develop ultimate load
capacities of at least twice the design working loads in
the designated load-bearing layers. Analysis shall show
that no soil layer underlying the designated load-bearing
layers causes the load-bearing capacity safety factor to
be less than two.

Bent piers or piles. The load-bearing capacity
of piers or piles discovered to have a sharp or sweeping
bend shall be determined by an approved method of
analysis or by load testing a representative pier or pile.

Overloads on piers or piles. The maximum
compressive load on any pier or pile due to mislocation
shall not exceed 110 percent of the allowable design
load.

International Building Code 1808.2.8.1

Determination of allowable loads. The
allowable axial and lateral loads on piers or piles shall be
determined by an approved formula, load tests or method
of analysis.

International Building Code 1808.2.8.2

Driving criteria. The allowable compressive
load on any pile where determined by the application of
an approved driving formula shall not exceed 40 tons
(356 kN). For allowable loads above 40 tons (356 kN),
the wave equation method of analysis shall be used to
estimate pile driveability of both driving stresses and net
displacement per blow at the ultimate load. Allowable
loads shall be verified by load tests in accordance with
Section 1808.2.8.3. The formula or wave equation load
shall be determined for gravity-drop or power-actuated
hammers and the hammer energy used shall be the maximum
consistent with the size, strength and weight of the
driven piles. The use of a follower is permitted only with
the approval of the building official. The introduction of
fresh hammer cushion or pile cushion material just prior
to final penetration is not permitted.

International Building Code 1808.2.8.3

Load tests. Where design compressive loads
per pier or pile are greater than those permitted by Section
1808.2.10 or where the design load for any pier or
pile foundation is in doubt, control test piers or piles shall
be tested in accordance with ASTM D 1143 or ASTM D
4945. At least one pier or pile shall be test loaded in each
area of uniform subsoil conditions. Where required by
the building official, additional piers or piles shall be
load tested where necessary to establish the safe design
capacity. The resulting allowable loads shall not be more
than one-half of the ultimate axial load capacity of the
test pier or pile as assessed by one of the published methods
listed in Section 1808.2.8.3.1 with consideration for
the test type, duration and subsoil. The ultimate axial
load capacity shall be determined by a registered design
professional with consideration given to tolerable total
and differential settlements at design load in accordance
with Section 1808.2.12. In subsequent installation of the
balance of foundation piles, all piles shall be deemed to
have a supporting capacity equal to the control pile
where such piles are of the same type, size and relative
length as the test pile; are installed using the same or
comparable methods and equipment as the test pile; are
installed in similar subsoil conditions as the test pile;
and, for driven piles, where the rate of penetration (e.g.,
net displacement per blow) of such piles is equal to or
less than that of the test pile driven with the same hammer
through a comparable driving distance.

Load test evaluation. It shall be permitted
to evaluate pile load tests with any of the following
methods:
1. Davisson Offset Limit.
2. Brinch-Hansen 90% Criterion.
3. Butler-Hoy Criterion.
4. Other methods approved by the building official.

International Building Code 1808.2.8.3.1

Load test evaluation. It shall be permitted
to evaluate pile load tests with any of the following
methods:
1. Davisson Offset Limit.
2. Brinch-Hansen 90% Criterion.
3. Butler-Hoy Criterion.
4. Other methods approved by the building official.

International Building Code 1808.2.8.4

Allowable frictional resistance. The
assumed frictional resistance developed by any pier or
uncased cast-in-place pile shall not exceed one-sixth of
the bearing value of the soil material at minimum depth
as set forth in Table 1804.2, up to a maximum of 500 psf
(24 kPa), unless a greater value is allowed by the building
official after a soil investigation, as specified in Section
1802, is submitted or a greater value is substantiated by a
load test in accordance with Section 1808.2.8.3. Frictional
resistance and bearing resistance shall not be
assumed to act simultaneously unless recommended by a
soil investigation as specified in Section 1802.

International Building Code 1808.2.8.5

Uplift capacity. Where required by the
design, the uplift capacity of a single pier or pile shall be
determined by an approved method of analysis based on
a minimum factor of safety of three or by load tests conducted
in accordance with ASTM D 3689. The maximum
allowable uplift load shall not exceed the ultimate
load capacity as determined in Section 1808.2.8.3
divided by a factor of safety of two. For pile groups subjected
to uplift, the allowable working uplift load for the
group shall be the lesser of:
1. The proposed individual pile uplift working load
times the number of piles in the group.
2. Two-thirds of the effective weight of the pile
group and the soil contained within a block defined
by the perimeter of the group and the length of the
pile.

International Building Code 1808.2.8.6

Load-bearing capacity. Piers, individual
piles and groups of piles shall develop ultimate load
capacities of at least twice the design working loads in
the designated load-bearing layers. Analysis shall show
that no soil layer underlying the designated load-bearing
layers causes the load-bearing capacity safety factor to
be less than two.

International Building Code 1808.2.8.7

Bent piers or piles. The load-bearing capacity
of piers or piles discovered to have a sharp or sweeping
bend shall be determined by an approved method of
analysis or by load testing a representative pier or pile.

International Building Code 1808.2.8.8

Overloads on piers or piles. The maximum
compressive load on any pier or pile due to mislocation
shall not exceed 110 percent of the allowable design
load.

International Building Code 1808.2.9

Lateral support.

General. Any soil other than fluid soil shall
be deemed to afford sufficient lateral support to the pier
or pile to prevent buckling and to permit the design of the
pier or pile in accordance with accepted engineering
practice and the applicable provisions of this code.

Unbraced piles. Piles standing unbraced in
air, water or in fluid soils shall be designed as columns in
accordance with the provisions of this code. Such piles
driven into firm ground can be considered fixed and laterally
supported at 5 feet (1524 mm) below the ground
surface and in soft material at 10 feet (3048 mm) below
the ground surface unless otherwise prescribed by the
360 2006 INTERNATIONAL BUILDING CODE
SOILS AND FOUNDATIONS
building official after a foundation investigation by an
approved agency.

Allowable lateral load. Where required by
the design, the lateral load capacity of a pier, a single pile
or a pile group shall be determined by an approved
method of analysis or by lateral load tests to at least twice
the proposed design working load. The resulting allowable
load shall not be more than one-half of that test load
that produces a gross lateralmovement of 1 inch (25 mm)
at the ground surface.

International Building Code 1808.2.9.1

General. Any soil other than fluid soil shall
be deemed to afford sufficient lateral support to the pier
or pile to prevent buckling and to permit the design of the
pier or pile in accordance with accepted engineering
practice and the applicable provisions of this code.

International Building Code 1808.2.9.2

Unbraced piles. Piles standing unbraced in
air, water or in fluid soils shall be designed as columns in
accordance with the provisions of this code. Such piles
driven into firm ground can be considered fixed and laterally
supported at 5 feet (1524 mm) below the ground
surface and in soft material at 10 feet (3048 mm) below
the ground surface unless otherwise prescribed by the
360 2006 INTERNATIONAL BUILDING CODE
SOILS AND FOUNDATIONS
building official after a foundation investigation by an
approved agency.

International Building Code 1808.2.9.3

Allowable lateral load. Where required by
the design, the lateral load capacity of a pier, a single pile
or a pile group shall be determined by an approved
method of analysis or by lateral load tests to at least twice
the proposed design working load. The resulting allowable
load shall not be more than one-half of that test load
that produces a gross lateralmovement of 1 inch (25 mm)
at the ground surface.