Team
Content
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. J
STANDARD GUIDELINES FOR THE DESIGN AND INSTALLATION OF PILE FOUNDATIONS
-1
or steel piles may be assumed from recognized standards. Where tip movement is measureci,the failure load may be defined as the load corresponding to a pile tip movement of 0.15 inches plus one percent of the tip diarneter. The foregoing interpretation applies to compression tests in which the load increments are held for Dotlonger than one half hour. For tests.in which test loads are held for longer than oue half hour, the settlement at the end of one half hour at each increment, including a load of twice the design load, shall be used to determine the failure load as defined in this section. For piJes tested with lateralload, the allowable lateral load should not be greater than 1/3 of the failure loadoThe design .load should not produce a gross deflection at fue pite top in excess of the lateral deflection specified by the Engin~r and/or acceptance criteria. Where appropriate. the single pile test results should be adjusted by accepted relationships to account for pite group response and pite head restraint. Where uplift capacity is a design consideration, load testing sbould be conducted as appropriate. For piles tested under uplift or tensile loads, the allowable design load sbould not be greater than.50 percent of the failure uplift 10a<1. or 50 percent of that load which produces a deflection deemed appropriate by the Engineer. Under some conditions, the uplift design load for a single pite may be assumed to be 33 percent of the ultimate frictionalloaa capacity dete111Ú1:1ed by compression testing of a comparable piJe, instruniented.in order todefinéthe
Building Codes or ASCE 7- 95 should be used. To these service loads. the following loads should be added as applicabJe. (a) (b) (c) (d) (e) Hydrostatic uplift; negative friction; dead load of pites and pite caps; fill or other overburden or surcharge loads acting on the foundation; latera1loads resulting from wind, earth pressurc, water pressure, wave action, ice, or seisnric action; uplift loads from swelling or expanding soits; impact; seisnric loads; loads due to eccentricity; any other pertinent 10ads.
(f) (g) (h) (i) (j)
5.2 MaxUnum Combination 01 Loads. The Ep,gineer should consider allloads acting on the piles and sbould investigate the combinabon of loads that can act coneurrently in producing maximum loads. When extreme win<1. wave. or earthquake loads are considered. an increase in design stress is permissible for ;ülowable stress design ooly. No sueh increase should be permitted for struetures whose design is controlJed by wind. seismic, or wave forces acting alone or in c:otnbiDaIioJt with dead load. 5.3 J»i.e_GI'O\I~m - --~-~ -------With respect to compressive loads, it is not necessary to coosider group efficiency except fora . group of fricUon piJes in cohesive soils or where fue pije spacing is less than 3 times the pile diameter in granular soils. In cohesive soils. the design load on a group of frietion pites should not exceed SOpercent of the ultimate load capacity determined by a (bJock) anaIysis summing the uJtiIDatebea.riQ¡ capacity of the soils within the plan area of fue group and the uJtimate shearing resistance on fue peripheral surfaceinscrib.iQgthe group. However. the capacity of the group shouId not exceed fue sum of the capacities of the individual piles in the group. The settlement of the pile group should not exceed the tolerable settlement linrits of the structure. The allowabJe working uplift load for a pile group should be thelesserof (1) the individual piJe design uplift load times the number of piles in fue group, (2) 2/3 of the effective weigbt of the pile group and the soil contained within a block defined by the perimeter of the group and the length oí the piles, or (3) 1/2 the effective weigbt of the pite
Ioadcarriedby shaft friction.
.
CHAPTER 5
Design Loads
5.1 Loads To Be Used The loads contributing to pile design loads consist of the serviee dead and live loads. including live load reductions. and ~ Joads. Wben applicabJe. the loading provisions from current, legally adopted 8
STANDARD
GUIDELlNES
FOR THE DESIGN ANO INSTALLATION
OF Pn.E FOUNDATIONS
group and soil contained within a block defined by the perimeter of the group and the pile length plus 1/2 the total shear on the peripheral surface of the block.
6.2 Timber PUes 6.1.1. Dimensions and stresses. Timber piles should be any species of wood for which clear wood strength values are given by ASTM 02555. Mínimum pile dimensions and other physical characteristics of timber piJes should be in accordance with ASTM 025. Allowable design stresses should not exceed those determined in aceordanee with ASTM 02899, Standard Method for Establishing Design Stresses for Round T1tDberPiJes, uoless substantiated by the requirements of Sec. 6.1.1. Determination of critieal scction for tapered piJes is required. 6.2.2 Preservadve treatmeftt. Preservative treatmtnt for timber piles and the treatment of piJe tops eut-off, should be as specified by American Wood PreserversAssociation Standard C-3, C-18, and M-4. Treatment should be specifically in accordance with the requirements for land or frcsh water use, for foundation pites entirely embedded in the ground, or for marine use. For marine construction, American Wood Prescrvers Association Standard C 18 should appIy. . 6.2.3 Untreated timber p~ Untreated timher pites should be used only if permanendy submerged and not subjcctcd to other detcriorating environments for the serviee life of the pites. 6.3 Concrete PUes 6.3.1 Reinforeed prtcast concrete pites. Conventionally reinforced precast eoncrete piJes should have-a mínimum dimensioríHmeasured through the center oí the pile of 8 inehes (203 mm). The concrete should have a mínimum specified 28day compressive strength (f'.) of 4000 psi ('1:7.6 MPa). Reinforcing stccl should have a mínimum yield strengtb of 40.000 psi (275.8 MPa). The allowabledesign axial eompressive stress should not exceed 33perccnt of the specificd mínimum concrete strengtb and 40 percent of the specified mínimumyield strengtb of the reinforcement, uoless substantiated by the requirements of Seco6.1.1. The allowable steel design stress in axial compression should not exceed 30,000 psi (206.8 MPa). . 6.3.2 Prestressed precast concrete pUes. Prestressed precast concrete piJes should have a minimum dimension measurcd through the center of the pite of 8 inehes (203 mm). The concrete sbould have a mínimum specified 28-day compressive strength (f'.) of 4000 psi (27.6 MPa). The allowable design axial compressive stress applicd to the full cross-section should not exeeed 33 percent of the specified mínimum concrete strengtb mínus 27 percent of the effective prestress force, uoless sub9
CHAPTER
6
.
Design Stresses
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r
6.1 General Thc dcsign stresscs in axial compression in this Standatd apply onJy to tb~ struetural capacity of embcdded foundation pilcs tbat are laterally supportcd. Unsupported pile Icngtbs should be designcd in accordance witb Sec. 3.5. PUcs should be dcsigncd to resist all forces imposed upon thcm during manufacture. transport, instaUation, and scrvicc. 6.1.1 U~ 01 bigber aDowable stres8es. Allow;' ablc stresses ¡rcatcr thm thosc specificd for each of the following piIc types shouldibe permitted when supportingoatifjiiStifjüfg-iUCllliígher streSScsare provided. Such S1JbFt--óstú1g data should ¡nelude successfuI pile load tescing in accordancc with Sec. 4.5, and one or more of the following. (1) Documentabon of ~vious satisfactory performance; (2) a subsurface foundation investigation analy~ sis spccifieaUy addressing the site, piJe type, and 108dinSconditions anticipated; (3) an analysis by wave equation methods to
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.
~
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investigatetbe drivingstressesindueeddur-
ing instaUation; (4) engineering surveillance of pile installation. including dynamic field measurements . when aoOiooriare. The design, analysis, load testing. and installation of the pile foundation uti1izingsuch higher allowable stresses should be under tbe direct supervision of a regi.stered professional engineer knowledgeable and experienccd in soil mechanics and the design and installation of pile foundations.
.._---
STANDARD
GUIDELINES
FOR THE OESIGN ANO INSTA.l.LA110N
OF PD.E FOUNDATIONS
stantiated by the requirements of Sec. 6.1. L 1ñe . , etfective prestress should notbe I~ dijm100 psi
(4.8 MPa).
.
6.3.3 Concrete-filled sh~Q pit.. CQR(;n;te:filled shell piles should have a mínimum dirnen:sion measured tbrough tbe cen~r oí tb.e pite ofS inches (203 rnm). The concreteshouldhave a minimum specified 28-day comprcssive strengtb (f' e) of 3000 psi (20.7 MPa)..!he steel portion of mandrel-driven corrugated steelshells and thin wall pipe witb a wall thickness oí lea tban 0.1 incbes (2.5 rnm) should not be CQIISidered load carrying. Shells or tubes should be strong enough to witbstand all driving andoinstaUatioaatles$es
.
and tOresist collapse.The allowabk.dcsignuial
compressive stress should not cxceed 33 percent of the specified mínimum concrete strengtb. unless substantiated by tberequirements of Seco6.1.1. Reinforcing stcel should be pIOvi~ as required to resist bending..lateral and uplift loading. and to prevent separation of concreted pites due to adjacent pile installation. or other construction operations. Reinforcing ateel shouldhave a mínimum yield strengtb oí 40.000 psi (275.8 MPa). The allowab1e design stress shQUldnot exceed 40 percent of tbe specified mínimum yield strengtb of tbe reinforcement, nor 30,000 psi (206.8MPa). Determination of critical section for tapered piles and otber nonuniform piles is required. 6.3.4 UDCa$Cd cast-iD-place and aucered pressun groated.coocrete pUes. Uncascd cast-in:-place
.
under tbis Standard include extruded concrete and precast concrete bases. Fo.. enlarged bases constructed witb uncased compacted concrete shafts, the allowable design compressive stress of the compacted concrete shaft should not exceed 25 percent of tbe specified mínimum 28-day compressive strengtb, unless substantiated by the requirements of Seco6.1.1. For cast-in-place con. crete shafts. the provisions of Seco6.3.3 or 6.3.4 should govern. For timber or structural steel shafts, tbe provisions of Seco6.2.1 and 6.4 should apply. Precast reinforced concrete base elements should meet tbe applicable provisions of Seco6.3. If designed for tension, tbe shaft should be connected to the base in a manner to develop tbe full teilsile 1000capacity of the shaft. Enlarged base pites should be consb1Jctedand installed in the same manner, utilizing comparable quantities of material. and should bear in tbe same
strata as successful prototype 1000 test pUes on the
,
1'"
projecL Unless thes~isdesicqe4.acolumn:in accordance wiUaSec. 3.5. any.anmdar ~ aroUDd~. tbe pile shaft Sbouldbe filled witb grout, sand. or otberapproved QWerial in.a nwmer acceptable tO tbe Engineer to re-establisb lateral support around tbe pile. 6.4 Steel Piles Rolled structural steel sections. steel pipe. and fully welded stcel piJes fabricated from plates or otber roUed sectionsshould conform to one of the appropriate stan~ specifications. Structural stecA piles, rolled and fabricated,sball conform to ASTM A36. ASTM AS72, or ASTM AS88. Steel pipe piles shall conform to ASTM A2S2:and have a mínimum yield strengtb of not leas tban 35.000 psi (248 MPa). Steel encased cast-in-placeconcrete piles shall conform tOASTM A2S2. ASTM A283. ASTM AS69, ASTM AS70. or ASTM A611. 6.4.1 AJIowable" [uu. Stee) piles shoUldbe proportioned for directaxial compression so as to not exceed an allowable design stressof 35%col tbe specified mínimum yieldstrengtb, unlesS substantiated by tbe requirements of Seco6.1.1. 6.4.2 Minimum dimensions, roIled steel H pUes, and fabricated pUes. Rolled structural sections and fabricated shapes should conform to the foIlowing mínimum dimensions. ( 1) The flange projections should not exceed 14 times tbe mínimum tbickness of metal in eitber tbe flange or tbe web, and theflange widtbs should not be less than 80% of tbe deptb of tbe section.
concretepUesinstalledby drillinc,augering,or
driving a tempOralycasing-aÚnandrel should have a minimwn diameter ol 8 inebes (203 mm)..The diameter for design uRder this Standard sbould not be greater than the outside diameter of tbeauger bit, drin. casing. or mandrel used to form tbe piJe shaft. AII piles sbould be designed tOresist bending. lateral and uplift loads, and to prevent separation and damage due to installation of adjacent piles or otber construction operation~ The concrete should have a mínimum specified 28-day compressive strengtb (f'e) of 3000 psi (20.7 MPa). The allowable design stress in axial compression should not exceed 33 percent of tbe specified mínimum concrete strength and 40 percent of the speci'fied minimum yield strength of tbe reinforcing steel, except tbat tbe allowable design stcel stress sbould not exceed 30.000 psi (206.8MPa). unless substantiated by the requirements of Seco6.1.1. 6.3.5 Enlarged base pUes. Enlarged base piles considered herein are formed by means otber tban drilling and under-reaming and are not considered as caissol1.." and drilled piers. Enlarged base pites 10
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STANDARD
GUlDELINES
FOIt.'I'R&
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OFPILE
~F;5ii!.~~~:';:";:~.--
FOUNDATIONS
(2) Th~ nominal depth of the section should ,not be less than 8 inches. For H sections, this should be measured in the direction of the web. (3) Flanges and 'webs should have a rninimum thickness of 0.375 inches (9.5 mm). Other dimensions may be used if they are substantiated by the requirements of Seco6.1.1. 6.4.3 Mínimum dimensions, steel pipe pUes. Pipe piles should have a minimum nominal outside diameter of 8 inches (203 mm). Steel pipe piles. top-driven and open-ended. should have a minimum wall thickness of 0.25 inches (6.4 rnm) for pipe diameters of 14 inches(355 rnm) or less. and 0.375 inches (9.5 rnm) for pipe diameters greater than 14 inches (355 rnm). Pipe of less wall thicknesses may be used when a suitable protective cutting shoe is used or if the pipe is completely filled with concrete. Pipe having a waII thickness less than 0.1 ¡nches (2.5 rnm) shall be considered Donloadcarrying. The allowable design stress for steel pipe filled with concrete after driving should meet the requirements of Seco6.4.4. Pipe not filled with concrete should meet the requirements of Sec. 6.4.1. Other dimensions may be used if they are substantiated by the requirements of Seco6.1.1. 6.4.4 Steel pipe or tubepiles-concrete fiUed. Steel pipe or tube piles shouldhavea lJIirUtTlum nominal outside diameter of 8-inches (203 rnm) ¡mQ. a minimum wall thickness of 0.1 inches (2.5 rnm). The allowable desjgn stressforsteel pipe or tube-~~ piles filled with concrete after driving should not exceed 35 percent of the mínimum yield strength of the steel and as detailed furth~r in Seco6.4.1. The allowable design axial compressive stress for the concrete fill should not exceed 33 percent of the specified mínimum concrete strength. Any reinforcing steel should have a minimum yield strength of 40,000 psi (275.8 MPa). The aIlowable design stress should not exceed 40 percent of the specified minimum yield strength of the reinforcement, ~ 30.000 psi (206.8 MPa). Higher aIlowable design stre$SeS may be used when substantiated by the requirements of Seco6.1.1. Top-driven open-ended piles, subsequently concrete filled, should have a mínimum waII thickness of 0.179 inches (4.5 rnm), but aIso not less than necessary to wjthstand aIl driving and insta1lation stresses, and preveot collapse. Longitudinally fluted steel tube piJes should be desjgned in accordance with the provisions of this section. but may have a minimum wall thickness ofO.12 inches (3 rnm), but also not less than that necessary to resist all driving
andinDstl~~.imdresist
flutect~~fiUecfWithconcrete
collapse. Such after
drivina;:Iftapeí~~ons are used.determination of critical'tecdoDiSrequired. fASc" -1'fI1""h ii_,';" ,h ""',;,~,.~--",.,.. '" or tube pUes.
M~sIJeI1 or tubCPiJes shouId be designocl,ia'accomancewithSec. 6.3.3. Steel shells or tubes -thAú&.l incbes (2.5 mm) should not be considaed 10be Ioad caajling~ Shells or tubes ~ ~stroiig:~!t~9&fLtD_withstandaII driviog andi~u~~añdtO_resist collapse. Such pi1e& sI1oIU.cI-f,iIQ \i'iifi.cODCrete after driving.
.
6.4,6' ~~~~~~pBes.
A caissonpile .
r-
'~should~~~'PiPe driven to roc~ cx~ by aosocket drlIIed:,intothe rock tbrough tbe opeQ.~ pipctaod ~ed with concrete. If required by tbt~P~~~~t shouId.be placed prior te coDcretiog and shou1dconsUt..Qf structural steelsectWnsarreinforcing steeLPipe... reinforcing ~ and;~stee1 core,.,~i'
"'"
shaUconfonn 10theappticaI?~~of~
Standard. Mínimum diametlZOt~~. . shou1dbe 15 ~.MuDmua'aUow"~ of pipe. reinfOlCÚi,.; an(f~~be ~accordancewitll applicable portioaa,of tbis Standard. Pipe sh~ha.ve a mipiJmUij:W~ tbickoess per the req~l1ts°~ sec;~. ~~~~'.1'I:I!..~um aIlowable StresS. on.the SIrI1CtUra1 steeJc;c;Rshou1dbe 50 percent of theq,ini~yie14 JCrenstb.The aIIowable design-streaforstMlpipe:bávig waII thiclcnesses of 0.1 incbe$ (2.5 aun) ar more fi11e4with c~ncre~
.
,
'
afterdriviol".shoutcf:11onxceed~'
perc.,pr.-Qt.¡;:-;--;~-'
----
,."~lIin~~~!,I!~~.~gtb" ~fthe ~l and ~.'ae'~,U~"f!i;:,,) ~:~er:~~.~6.4.1._The_alI()wabledesign ~ia1 compressive stress far the concrete fill should not exceed 31 pelcent of the specified minimum concrete stm1Jtl1. Any,reinfcxy;ingsteel should have a mínimum yieid strength of4O.ooo psi (275.8 MPa). The alJpw~1e .design ~ should not exceed 40 percentofJbe~~Jninimum yield strength of ._=the_l'!@r~t,--:-Q.Qt30,ooopsí (206.8 MPa). The maximulllaUowable stress 00 other steel core mAtP.ri~~~_~exceed 40 perceot of the mini..mUaiyi'é{lstl;iigtli"l3S.000 psi), nar 30,000 psi {206.8 MPa.)~~HigheralIowable desigo stresses may be used when substantiated by requirements of Sec. 6.1.1~
.
6.4.7 Composite and other piJe types. PiJes of a typC. c()nfiguration, or material not specifiCally covered by this Standard. should confonn to all applicable provisions of the Standard. including the provisions of Sec. 6.1.1. Such pites. or pil«:types. haviog adesign looo'of25 tons (222lcN) ar ~att'r should have the capacity prOveo: by load I~lit10
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--~
. J
STANDARD GUIDELINES FOR THE DESIGN AND INSTALLATION OF PILE FOUNDATIONS
-1
or steel piles may be assumed from recognized standards. Where tip movement is measureci,the failure load may be defined as the load corresponding to a pile tip movement of 0.15 inches plus one percent of the tip diarneter. The foregoing interpretation applies to compression tests in which the load increments are held for Dotlonger than one half hour. For tests.in which test loads are held for longer than oue half hour, the settlement at the end of one half hour at each increment, including a load of twice the design load, shall be used to determine the failure load as defined in this section. For piJes tested with lateralload, the allowable lateral load should not be greater than 1/3 of the failure loadoThe design .load should not produce a gross deflection at fue pite top in excess of the lateral deflection specified by the Engin~r and/or acceptance criteria. Where appropriate. the single pile test results should be adjusted by accepted relationships to account for pite group response and pite head restraint. Where uplift capacity is a design consideration, load testing sbould be conducted as appropriate. For piles tested under uplift or tensile loads, the allowable design load sbould not be greater than.50 percent of the failure uplift 10a<1. or 50 percent of that load which produces a deflection deemed appropriate by the Engineer. Under some conditions, the uplift design load for a single pite may be assumed to be 33 percent of the ultimate frictionalloaa capacity dete111Ú1:1ed by compression testing of a comparable piJe, instruniented.in order todefinéthe
Building Codes or ASCE 7- 95 should be used. To these service loads. the following loads should be added as applicabJe. (a) (b) (c) (d) (e) Hydrostatic uplift; negative friction; dead load of pites and pite caps; fill or other overburden or surcharge loads acting on the foundation; latera1loads resulting from wind, earth pressurc, water pressure, wave action, ice, or seisnric action; uplift loads from swelling or expanding soits; impact; seisnric loads; loads due to eccentricity; any other pertinent 10ads.
(f) (g) (h) (i) (j)
5.2 MaxUnum Combination 01 Loads. The Ep,gineer should consider allloads acting on the piles and sbould investigate the combinabon of loads that can act coneurrently in producing maximum loads. When extreme win<1. wave. or earthquake loads are considered. an increase in design stress is permissible for ;ülowable stress design ooly. No sueh increase should be permitted for struetures whose design is controlJed by wind. seismic, or wave forces acting alone or in c:otnbiDaIioJt with dead load. 5.3 J»i.e_GI'O\I~m - --~-~ -------With respect to compressive loads, it is not necessary to coosider group efficiency except fora . group of fricUon piJes in cohesive soils or where fue pije spacing is less than 3 times the pile diameter in granular soils. In cohesive soils. the design load on a group of frietion pites should not exceed SOpercent of the ultimate load capacity determined by a (bJock) anaIysis summing the uJtiIDatebea.riQ¡ capacity of the soils within the plan area of fue group and the uJtimate shearing resistance on fue peripheral surfaceinscrib.iQgthe group. However. the capacity of the group shouId not exceed fue sum of the capacities of the individual piles in the group. The settlement of the pile group should not exceed the tolerable settlement linrits of the structure. The allowabJe working uplift load for a pile group should be thelesserof (1) the individual piJe design uplift load times the number of piles in fue group, (2) 2/3 of the effective weigbt of the pile group and the soil contained within a block defined by the perimeter of the group and the length oí the piles, or (3) 1/2 the effective weigbt of the pite
Ioadcarriedby shaft friction.
.
CHAPTER 5
Design Loads
5.1 Loads To Be Used The loads contributing to pile design loads consist of the serviee dead and live loads. including live load reductions. and ~ Joads. Wben applicabJe. the loading provisions from current, legally adopted 8
STANDARD
GUIDELlNES
FOR THE DESIGN ANO INSTALLATION
OF Pn.E FOUNDATIONS
group and soil contained within a block defined by the perimeter of the group and the pile length plus 1/2 the total shear on the peripheral surface of the block.
6.2 Timber PUes 6.1.1. Dimensions and stresses. Timber piles should be any species of wood for which clear wood strength values are given by ASTM 02555. Mínimum pile dimensions and other physical characteristics of timber piJes should be in accordance with ASTM 025. Allowable design stresses should not exceed those determined in aceordanee with ASTM 02899, Standard Method for Establishing Design Stresses for Round T1tDberPiJes, uoless substantiated by the requirements of Sec. 6.1.1. Determination of critieal scction for tapered piJes is required. 6.2.2 Preservadve treatmeftt. Preservative treatmtnt for timber piles and the treatment of piJe tops eut-off, should be as specified by American Wood PreserversAssociation Standard C-3, C-18, and M-4. Treatment should be specifically in accordance with the requirements for land or frcsh water use, for foundation pites entirely embedded in the ground, or for marine use. For marine construction, American Wood Prescrvers Association Standard C 18 should appIy. . 6.2.3 Untreated timber p~ Untreated timher pites should be used only if permanendy submerged and not subjcctcd to other detcriorating environments for the serviee life of the pites. 6.3 Concrete PUes 6.3.1 Reinforeed prtcast concrete pites. Conventionally reinforced precast eoncrete piJes should have-a mínimum dimensioríHmeasured through the center oí the pile of 8 inehes (203 mm). The concrete should have a mínimum specified 28day compressive strength (f'.) of 4000 psi ('1:7.6 MPa). Reinforcing stccl should have a mínimum yield strengtb of 40.000 psi (275.8 MPa). The allowabledesign axial eompressive stress should not exceed 33perccnt of the specificd mínimum concrete strengtb and 40 percent of the specified mínimumyield strengtb of the reinforcement, uoless substantiated by the requirements of Seco6.1.1. The allowable steel design stress in axial compression should not exceed 30,000 psi (206.8 MPa). . 6.3.2 Prestressed precast concrete pUes. Prestressed precast concrete piJes should have a minimum dimension measurcd through the center of the pite of 8 inehes (203 mm). The concrete sbould have a mínimum specified 28-day compressive strength (f'.) of 4000 psi (27.6 MPa). The allowable design axial compressive stress applicd to the full cross-section should not exeeed 33 percent of the specified mínimum concrete strengtb mínus 27 percent of the effective prestress force, uoless sub9
CHAPTER
6
.
Design Stresses
\
r
6.1 General Thc dcsign stresscs in axial compression in this Standatd apply onJy to tb~ struetural capacity of embcdded foundation pilcs tbat are laterally supportcd. Unsupported pile Icngtbs should be designcd in accordance witb Sec. 3.5. PUcs should be dcsigncd to resist all forces imposed upon thcm during manufacture. transport, instaUation, and scrvicc. 6.1.1 U~ 01 bigber aDowable stres8es. Allow;' ablc stresses ¡rcatcr thm thosc specificd for each of the following piIc types shouldibe permitted when supportingoatifjiiStifjüfg-iUCllliígher streSScsare provided. Such S1JbFt--óstú1g data should ¡nelude successfuI pile load tescing in accordancc with Sec. 4.5, and one or more of the following. (1) Documentabon of ~vious satisfactory performance; (2) a subsurface foundation investigation analy~ sis spccifieaUy addressing the site, piJe type, and 108dinSconditions anticipated; (3) an analysis by wave equation methods to
.. -
.
~
--
investigatetbe drivingstressesindueeddur-
ing instaUation; (4) engineering surveillance of pile installation. including dynamic field measurements . when aoOiooriare. The design, analysis, load testing. and installation of the pile foundation uti1izingsuch higher allowable stresses should be under tbe direct supervision of a regi.stered professional engineer knowledgeable and experienccd in soil mechanics and the design and installation of pile foundations.
.._---
STANDARD
GUIDELINES
FOR THE OESIGN ANO INSTA.l.LA110N
OF PD.E FOUNDATIONS
stantiated by the requirements of Sec. 6.1. L 1ñe . , etfective prestress should notbe I~ dijm100 psi
(4.8 MPa).
.
6.3.3 Concrete-filled sh~Q pit.. CQR(;n;te:filled shell piles should have a mínimum dirnen:sion measured tbrough tbe cen~r oí tb.e pite ofS inches (203 rnm). The concreteshouldhave a minimum specified 28-day comprcssive strengtb (f' e) of 3000 psi (20.7 MPa)..!he steel portion of mandrel-driven corrugated steelshells and thin wall pipe witb a wall thickness oí lea tban 0.1 incbes (2.5 rnm) should not be CQIISidered load carrying. Shells or tubes should be strong enough to witbstand all driving andoinstaUatioaatles$es
.
and tOresist collapse.The allowabk.dcsignuial
compressive stress should not cxceed 33 percent of the specified mínimum concrete strengtb. unless substantiated by tberequirements of Seco6.1.1. Reinforcing stcel should be pIOvi~ as required to resist bending..lateral and uplift loading. and to prevent separation of concreted pites due to adjacent pile installation. or other construction operations. Reinforcing ateel shouldhave a mínimum yield strengtb oí 40.000 psi (275.8 MPa). The allowab1e design stress shQUldnot exceed 40 percent of tbe specified mínimum yield strengtb of tbe reinforcement, nor 30,000 psi (206.8MPa). Determination of critical section for tapered piles and otber nonuniform piles is required. 6.3.4 UDCa$Cd cast-iD-place and aucered pressun groated.coocrete pUes. Uncascd cast-in:-place
.
under tbis Standard include extruded concrete and precast concrete bases. Fo.. enlarged bases constructed witb uncased compacted concrete shafts, the allowable design compressive stress of the compacted concrete shaft should not exceed 25 percent of tbe specified mínimum 28-day compressive strengtb, unless substantiated by the requirements of Seco6.1.1. For cast-in-place con. crete shafts. the provisions of Seco6.3.3 or 6.3.4 should govern. For timber or structural steel shafts, tbe provisions of Seco6.2.1 and 6.4 should apply. Precast reinforced concrete base elements should meet tbe applicable provisions of Seco6.3. If designed for tension, tbe shaft should be connected to the base in a manner to develop tbe full teilsile 1000capacity of the shaft. Enlarged base pites should be consb1Jctedand installed in the same manner, utilizing comparable quantities of material. and should bear in tbe same
strata as successful prototype 1000 test pUes on the
,
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projecL Unless thes~isdesicqe4.acolumn:in accordance wiUaSec. 3.5. any.anmdar ~ aroUDd~. tbe pile shaft Sbouldbe filled witb grout, sand. or otberapproved QWerial in.a nwmer acceptable tO tbe Engineer to re-establisb lateral support around tbe pile. 6.4 Steel Piles Rolled structural steel sections. steel pipe. and fully welded stcel piJes fabricated from plates or otber roUed sectionsshould conform to one of the appropriate stan~ specifications. Structural stecA piles, rolled and fabricated,sball conform to ASTM A36. ASTM AS72, or ASTM AS88. Steel pipe piles shall conform to ASTM A2S2:and have a mínimum yield strengtb of not leas tban 35.000 psi (248 MPa). Steel encased cast-in-placeconcrete piles shall conform tOASTM A2S2. ASTM A283. ASTM AS69, ASTM AS70. or ASTM A611. 6.4.1 AJIowable" [uu. Stee) piles shoUldbe proportioned for directaxial compression so as to not exceed an allowable design stressof 35%col tbe specified mínimum yieldstrengtb, unlesS substantiated by tbe requirements of Seco6.1.1. 6.4.2 Minimum dimensions, roIled steel H pUes, and fabricated pUes. Rolled structural sections and fabricated shapes should conform to the foIlowing mínimum dimensions. ( 1) The flange projections should not exceed 14 times tbe mínimum tbickness of metal in eitber tbe flange or tbe web, and theflange widtbs should not be less than 80% of tbe deptb of tbe section.
concretepUesinstalledby drillinc,augering,or
driving a tempOralycasing-aÚnandrel should have a minimwn diameter ol 8 inebes (203 mm)..The diameter for design uRder this Standard sbould not be greater than the outside diameter of tbeauger bit, drin. casing. or mandrel used to form tbe piJe shaft. AII piles sbould be designed tOresist bending. lateral and uplift loads, and to prevent separation and damage due to installation of adjacent piles or otber construction operation~ The concrete should have a mínimum specified 28-day compressive strengtb (f'e) of 3000 psi (20.7 MPa). The allowable design stress in axial compression should not exceed 33 percent of tbe specified mínimum concrete strength and 40 percent of the speci'fied minimum yield strength of tbe reinforcing steel, except tbat tbe allowable design stcel stress sbould not exceed 30.000 psi (206.8MPa). unless substantiated by the requirements of Seco6.1.1. 6.3.5 Enlarged base pUes. Enlarged base piles considered herein are formed by means otber tban drilling and under-reaming and are not considered as caissol1.." and drilled piers. Enlarged base pites 10
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STANDARD
GUlDELINES
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FOUNDATIONS
(2) Th~ nominal depth of the section should ,not be less than 8 inches. For H sections, this should be measured in the direction of the web. (3) Flanges and 'webs should have a rninimum thickness of 0.375 inches (9.5 mm). Other dimensions may be used if they are substantiated by the requirements of Seco6.1.1. 6.4.3 Mínimum dimensions, steel pipe pUes. Pipe piles should have a minimum nominal outside diameter of 8 inches (203 mm). Steel pipe piles. top-driven and open-ended. should have a minimum wall thickness of 0.25 inches (6.4 rnm) for pipe diameters of 14 inches(355 rnm) or less. and 0.375 inches (9.5 rnm) for pipe diameters greater than 14 inches (355 rnm). Pipe of less wall thicknesses may be used when a suitable protective cutting shoe is used or if the pipe is completely filled with concrete. Pipe having a waII thickness less than 0.1 ¡nches (2.5 rnm) shall be considered Donloadcarrying. The allowable design stress for steel pipe filled with concrete after driving should meet the requirements of Seco6.4.4. Pipe not filled with concrete should meet the requirements of Sec. 6.4.1. Other dimensions may be used if they are substantiated by the requirements of Seco6.1.1. 6.4.4 Steel pipe or tubepiles-concrete fiUed. Steel pipe or tube piles shouldhavea lJIirUtTlum nominal outside diameter of 8-inches (203 rnm) ¡mQ. a minimum wall thickness of 0.1 inches (2.5 rnm). The allowable desjgn stressforsteel pipe or tube-~~ piles filled with concrete after driving should not exceed 35 percent of the mínimum yield strength of the steel and as detailed furth~r in Seco6.4.1. The allowable design axial compressive stress for the concrete fill should not exceed 33 percent of the specified mínimum concrete strength. Any reinforcing steel should have a minimum yield strength of 40,000 psi (275.8 MPa). The aIlowable design stress should not exceed 40 percent of the specified minimum yield strength of the reinforcement, ~ 30.000 psi (206.8 MPa). Higher aIlowable design stre$SeS may be used when substantiated by the requirements of Seco6.1.1. Top-driven open-ended piles, subsequently concrete filled, should have a mínimum waII thickness of 0.179 inches (4.5 rnm), but aIso not less than necessary to wjthstand aIl driving and insta1lation stresses, and preveot collapse. Longitudinally fluted steel tube piJes should be desjgned in accordance with the provisions of this section. but may have a minimum wall thickness ofO.12 inches (3 rnm), but also not less than that necessary to resist all driving
andinDstl~~.imdresist
flutect~~fiUecfWithconcrete
collapse. Such after
drivina;:Iftapeí~~ons are used.determination of critical'tecdoDiSrequired. fASc" -1'fI1""h ii_,';" ,h ""',;,~,.~--",.,.. '" or tube pUes.
M~sIJeI1 or tubCPiJes shouId be designocl,ia'accomancewithSec. 6.3.3. Steel shells or tubes -thAú&.l incbes (2.5 mm) should not be considaed 10be Ioad caajling~ Shells or tubes ~ ~stroiig:~!t~9&fLtD_withstandaII driviog andi~u~~añdtO_resist collapse. Such pi1e& sI1oIU.cI-f,iIQ \i'iifi.cODCrete after driving.
.
6.4,6' ~~~~~~pBes.
A caissonpile .
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'~should~~~'PiPe driven to roc~ cx~ by aosocket drlIIed:,intothe rock tbrough tbe opeQ.~ pipctaod ~ed with concrete. If required by tbt~P~~~~t shouId.be placed prior te coDcretiog and shou1dconsUt..Qf structural steelsectWnsarreinforcing steeLPipe... reinforcing ~ and;~stee1 core,.,~i'
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shaUconfonn 10theappticaI?~~of~
Standard. Mínimum diametlZOt~~. . shou1dbe 15 ~.MuDmua'aUow"~ of pipe. reinfOlCÚi,.; an(f~~be ~accordancewitll applicable portioaa,of tbis Standard. Pipe sh~ha.ve a mipiJmUij:W~ tbickoess per the req~l1ts°~ sec;~. ~~~~'.1'I:I!..~um aIlowable StresS. on.the SIrI1CtUra1 steeJc;c;Rshou1dbe 50 percent of theq,ini~yie14 JCrenstb.The aIIowable design-streaforstMlpipe:bávig waII thiclcnesses of 0.1 incbe$ (2.5 aun) ar more fi11e4with c~ncre~
.
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afterdriviol".shoutcf:11onxceed~'
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,."~lIin~~~!,I!~~.~gtb" ~fthe ~l and ~.'ae'~,U~"f!i;:,,) ~:~er:~~.~6.4.1._The_alI()wabledesign ~ia1 compressive stress far the concrete fill should not exceed 31 pelcent of the specified minimum concrete stm1Jtl1. Any,reinfcxy;ingsteel should have a mínimum yieid strength of4O.ooo psi (275.8 MPa). The alJpw~1e .design ~ should not exceed 40 percentofJbe~~Jninimum yield strength of ._=the_l'!@r~t,--:-Q.Qt30,ooopsí (206.8 MPa). The maximulllaUowable stress 00 other steel core mAtP.ri~~~_~exceed 40 perceot of the mini..mUaiyi'é{lstl;iigtli"l3S.000 psi), nar 30,000 psi {206.8 MPa.)~~HigheralIowable desigo stresses may be used when substantiated by requirements of Sec. 6.1.1~
.
6.4.7 Composite and other piJe types. PiJes of a typC. c()nfiguration, or material not specifiCally covered by this Standard. should confonn to all applicable provisions of the Standard. including the provisions of Sec. 6.1.1. Such pites. or pil«:types. haviog adesign looo'of25 tons (222lcN) ar ~att'r should have the capacity prOveo: by load I~lit10
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