PileFooting Connections A Survey of State Practice by tho13076

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									                   Pile/Footing Connections: A Survey of State Practice
                                                  Prepared for
                                   Geotechnics Technical Oversight Committee
                                     Wisconsin Highway Research Program

                                                Prepared by
                                            CTC & Associates LLC
                                        WisDOT Research & Library Unit
                                               March 5, 2009

Transportation Synthesis Reports are brief summaries of currently available information on topics of interest to
WisDOT staff throughout the department. Online and print sources for TSRs include NCHRP and other TRB
programs, AASHTO, the research and practices of other transportation agencies, and related academic and
industry research. Internet hyperlinks in TSRs are active at the time of publication, but changes on the host server
can make them obsolete. To request a TSR, e-mail research@dot.state.wi.us or call (608) 261-8198.

Request for Report
The Wisconsin Highway Research Program’s Geotechnics Technical Oversight Committee requested a synthesis
report on the state of the practice with regard to pile connection to footings, specifically the minimum embedment
required in a pile footing to ensure fixity.

Summary
The AASHTO LRFD Bridge Design Specifications require that the tops of piles project at least 12 inches into the
pile cap, or a reduced embedment of at least 6 inches if the pile is attached to the cap with embedded bars or strands
(see Section 10.7.1.2, “Minimum Pile Spacing, Clearance and Embedment into Cap”).

We reviewed the bridge design manuals of 14 northern states to identify how state DOTs are applying the AASHTO
guidance in their State Specifications with regard to minimum pile embedment in footings, with a particular interest
in minimum embedment to ensure fixity. This table summarizes our findings with regard to minimum embedment in
a pile footing:

                                          Minimum Embedment in
         Pile Type                                                          State
                                          Footing
         Cast-in-place pile               6 inches                          NY
         Driven pile                      1 foot                            CT, IL, IN, MN, ND, NY, OR
                                          1 to 2 feet                       IA, OH
                                          2 feet                            WA
                                          750 millimeters (2.5 feet)        MT
                                          3 feet                            NE, NJ
         Integral abutment pile           2 feet                            ID
                                          3 feet                            ND




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Most of the state DOT bridge design manuals we reviewed indicated minimum embedment in the footing or
abutment but did not specify the minimum embedment required to ensure fixity. Of the manuals we reviewed, only
two addressed fixity:

    Illinois
    • Integral abutment piling shall extend 2 feet into the abutment to assure pile fixity.
    • Where piles are required to resist large lateral loadings by soil/structure interaction (also known as pile
         flexure or pile fixity), the piles may be embedded 2 feet into the abutment or footing to ensure top of pile
         fixity and reduce deflection.

    Oregon
    • Typical minimum embedment to develop fixity:
               Piles                                      Minimum
                                                          Embedment
               HP 10X42 and HP 12x53                       20 inches
               HP 12X74 and HP 14X89                      24 inches
               HP 14X117                                  27 inches
               PP 10 ¾ X 0.38 and PP 12 ¾ X 0.38          15 inches
               PP 16 X 0.38 and PP 16 X 0.50              20 inches

State Specifications
Connecticut
Bridge Design Manual, 2003
http://www.ct.gov/dot/lib/dot/documents/dpublications/bridge/bdm.pdf
See page 79 of the PDF:

    5.14.4 Driven Piles (see the third paragraph in this subsection)
    Pile foundations supporting abutments shall have a minimum of two rows of piles, unless the piles are
    incorporated into a fully integral abutment. Piles shall be anchored to and embedded in the footings a minimum
    of twelve inches.

Idaho
Bridge Design LRFD Manual, April 2008
http://itd.idaho.gov/bridge/manual/manual_April08.pdf
See page 166 of the PDF:

    Design Limitations for the Use of Integral Abutments
    Foundations: Abutments shall be supported on a single row of steel H-piles, steel smooth hollow pipe pile or
    steel-encased concrete piles utilizing smooth steel tubes. Piles should be embedded into the abutment concrete
    at least 2 feet. The preferred orientation of the piles is for bending about the strong axis. On skewed bridges the
    pile flanges should remain parallel with the abutment.

Illinois
Bridge Manual, 2008
http://www.dot.il.gov/bridges/pdf/Bridge%20Manual_2008.exe (unzip file to open PDF)
See page 570 of the PDF:

    3.10.1.12 Pile Connection to Abutments, Piers and Footings
    Piles supporting footings or non-integral abutments shall extend 12 in. into the structure. Integral abutment
    piling shall extend 2 ft. into the abutment to assure pile fixity. Reinforcement shall be placed to maintain 3 in.
    clearance from the bottom of the footing and arranged in such a manner to allow the pile to project into the
    footing or abutment. Pile bent piers shall have their piling extend through the individual or solid wall
    encasement 12 in. into the pier cap. Where piles are required to resist large lateral loadings by soil/structure
    interaction (also known as pile flexure or pile fixity), the piles may be embedded 2 ft. into the abutment or
    footing to ensure top of pile fixity and reduce deflection.




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Indiana
Indiana Design Manual, Chapter 66, 2008
http://www.in.gov/dot/div/contracts/standards/dm/english/Part6/ECh66/ch66.htm
See page 17 of the PDF:

    66-3.04 Design Requirements
    3. Embedment. Article 10.7.1.5 also specifies that pile tops should project not less than 1 ft into the footing
        after all damaged pile material has been removed. Embedment of piles into the stem of a wall pier with a
        single row of piles should be a minimum of 5 ft.

Find links to all chapters of the Indiana Design Manual at http://www.in.gov/dot/div/contracts/standards/dm/english/.

Iowa
LRFD Bridge Design Manual, January 2008
ftp://165.206.203.34/dotmain/bridges/policy/LRFDBridgeDesignManual.pdf
See page 179 of the PDF:

    Table 6.2.5. Minimum pile embedment and pile head reinforcing

     Substructure element                                        Minimum               Pile head reinforcing
                                                                 embedment
     Integral abutment for A or B pretensioned prestressed       2 feet (600 mm)       Spiral (1)
     concrete beams (PPCBs)
     Integral abutment for C, D, BTB, BTC, BTD, or BTE           2 feet (600 mm)       Spiral (1) and bent p bars
                                                                                       (2)
     pretensioned prestressed concrete beams (PPCBs)
     Integral abutment for steel plate girders                   2 feet (600 mm)       Spiral (1) (3) and
                                                                                       bent p bars (2) (3)
     Stub abutment on timber piles                               2 feet (600 mm)       Spiral (3)
     Stub abutment on steel piles                                2 feet (600 mm)       None (4)
     Pier footing                                                1 foot (300 mm)       None (3)
     Continuous concrete slab pile bent cap (not monolithic      1.5 feet (460 mm)     None (3)
     with slab)
     Continuous concrete slab pile bent cap (monolithic with 1 foot (300 mm)         Cap steel (bent dowels) (5)
     slab)
      Table notes:
        (1) Spiral is placed around each pile head as detailed on standard sheets [OBS SS 2078-
             2091]. The spiral should not be epoxy coated.
        (2) For the bent p bars see the Abutment Pile Plan on standard sheets [OBS SS 2085-2091].
        (3) No standard sheet is available.
        (4) See standard sheets for C or D beams [OBS SS 2092-2105].
        (5) Cap steel (bent dowels) is detailed on a standard sheet [OBS SS P10L].

Minnesota
LRFD Bridge Design Manual, Section 10: Foundations, June 2007
http://www.dot.state.mn.us/bridge/Manuals/LRFD/LRFD-Manual.pdf
See pages 519 and 520 of the PDF:

    Clear Spacing and Minimum Concrete Cover
    The minimum concrete cover for piles is 9 inches. To facilitate pile driving operations, the minimum center-to-
    center pile spacing is 2'-6" with 3'-0" minimum preferred.
    It may be necessary to increase the plan dimensions of a footing or pile cap when using battered piles to provide
    the minimum concrete cover of 9 inches.
    The standard embedment into a pier or high parapet abutment footing for a driven pile is one foot and should be
    dimensioned in the plans. Assume the piles are pinned supports.
    The standard pile embedment for a low parapet abutment footing is 2'-4".



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Montana
Montana Structures Manual Part II, Chapter 20: Foundations, August 2002
http://www.mdt.mt.gov/other/bridge/external/structures-manual/part_II/chp-20-final.pdf
See page 7 of the PDF:

    20.2.1 Minimum Dimensions/Materials
    The following criteria shall apply:

    1. Footing and Cap Thickness:
        a. Spread Footings: 600 mm
        b. Pile Caps: 750 mm

Find links to all parts of the Montana Structures Manual at
http://www.mdt.mt.gov/publications/manuals.shtml#design, including Parts I and II as well as Geotechnical and
Hydraulic Design.

Nebraska
Bridge Operations, Policies & Procedures, December 2008
http://www.dor.state.ne.us/design/bridge/bopp/2008_BOPP_Manual(web).pdf
See page 205 of the PDF:

    Pier Footings
    • The minimum thickness of any footing supported on piles shall be 3 feet.
    • For highway crossings, a minimum vertical distance of 3 feet shall be provided between ground elevation
        and the top of any pier footing.
    • For railroad crossings, the minimum footing embedment shall conform to railroad requirements (see
        Section 1.2.1, Page 1.11).
    • For water crossings, the hydraulic section shall determine pier footings elevations to provide adequate
        scour protection.

New Jersey
Bridges and Structures Design Manual, Section 16: Foundations Design Criteria, 2002
http://www.nj.gov/transportation/eng/documents/BDME/zip/BridgeDesignManualDocs.zip
Select File-26-SEC 16.doc from the list of files that appears when opening the zip file above. See page 2 of the
Word file:

    2.   Pile Foundations
         a. As stated above, pile foundation designs shall be based on the criteria that is stated on page 1.3-21 of
              this Manual.
         b. The minimum pile cap thickness shall be 3 feet.

New York
Bridge Manual, January 2008
https://www.nysdot.gov/divisions/engineering/structures/repository/manuals/brman-
usc/Complete_nysdot_US_2008_1st.pdf
See the second paragraph on page 272 of the PDF:

    The tops of C.I.P. piles shall be embedded 6" into the footing. The tops of all other piles shall be embedded 1'-
    0" into the footing.

North Dakota
LRFD Bridge Design Manual, Chapter 10: Foundations, February 2008
http://www.dot.nd.gov/manuals/bridge/lrfd-bridge-design/Section10A.pdf
See page 1 of the PDF:

    10.2 Piles
    It may be necessary to increase the plan dimensions of a footing or pile cap when using battered piles.



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    The standard embedment into a pier or abutment footing for a driven pile is one foot and shall be dimensioned
    in the plans.

See page 5 of the PDF:

    10.4.2 Pile Embedment
    Piles shall be embedded a minimum of three feet into the wall of integral type abutments. For wall piers with a
    single row of piling, pile embedment shall be at least height of wall/ 3, but not less than 4'-0". Maximum
    embedment shall be governed by punching shear.

Find links to all chapters of the LRFD Bridge Design Manual at http://www.dot.nd.gov/manuals/bridge/lrfd-bridge-
design/lrfd-bridge.htm.

Ohio
Bridge Design Manual, 2007
http://www.dot.state.oh.us/Divisions/HighwayOps/Structures/standard/Bridges/BDM/BDM2007/BDM2007_07-18-
08.pdf
See page 180 of the PDF:

    303.4.2.3 Pile Embedment
    Piles supporting capped pile piers shall be embedded 1'-6" [450 mm] into the concrete cap. Other substructure
    units on a single row of piles should have the piles embedded 2'-0" [600 mm] into the concrete. A 1'-0" [300
    mm] embedment depth into the concrete footing is required for all other cases. In every case, there shall be at
    least 1'-6" [450 mm] cover over top of pile.

Oregon
Bridge Design and Drafting Manual 2004
http://www.oregon.gov/ODOT/HWY/BRIDGE/docs/BDDM/apr-2008_finals/section_1-2004_apr08.pdf
See page 59 of the PDF:

    Steel Pile Footing Embedment to Develop Fixity. It may be necessary to develop lateral load resistance in
    piles or pile groups. To develop the required lateral load capacities, piles must be embedded in pile caps or
    footings adequately to develop the full moment capacity of the pile section.

    If lateral load capacity is not needed, a pile embedment length of 12 inches is sufficient.

    Typical minimum embedment to develop fixity for f'c = 3.3 ksi and fb = 36 ksi is:
          Piles                                        Minimum Embedment
          HP 10X42 and HP 12x53                               20”
          HP 12X74 and HP 14X89                               24”
          HP 14X117                                           27”
          PP 10 ¾ X 0.38 and PP 12 ¾ X 0.38                   15”
          PP 16 X 0.38 and PP 16 X 0.50                       20”

Washington
Bridge Design Manual, May 2008
http://www.wsdot.wa.gov/publications/manuals/fulltext/M23-50/BDM.pdf
See page 952 of the PDF:

    7.7.5 Footing Concrete Design on Pile Supports
    The minimum footing thickness shall be 2 feet 0 inches. The minimum plan dimension shall be 4 feet 0 inches.
    Footing thickness may be governed by the development length of the column dowels, or by concrete shear
    requirements. The use of strut and tie modeling is recommended for the design of all pile caps and pile footings
    Figure 7.7.5-1 identifies the modes of failure that should be investigated for general pile cap/footing design.




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