GuidetoDesign Manufacture andInstallationofConcretePiles
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AmericanConcreteInstitute?
AmericanConcreteInstituteAdancing concrete notoledge
GuidetoDesign Manufacture andInstallationof ConcretePiles
andInstallation of Concrete Piles Guide toDesign Manufacture
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Reported byACI Committee543
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hisppemdriisdsichenineerfrcdr thedesigfedilfmfpiles.
Chapter2-Notation and definitions p.5
2.1-Notation2.2-Definitions
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Chapter 3-Geotechnical design considerations p.5
Keywdaped sengcapcity:cmpsie cctio concrele piles: sion: dilled iles; foundations; harfor stctures:lodsprcnqalyrinfor；mechanics: sorage; lolerances.
3.1General 3.2-Subsurface conditions3.3Bearng capacity of individual pils3.5-Group action in pression 3.4Settlemen3.7Lateral support 3.6-Pile spacing3.8-Batter piles3.10-Long-tem perfomance 3.9-Axial load distribution3.12-Uplift capacity 3.11Lateral capacity
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CONTENTS
Chapter 1-Introduction p.2
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1.1-General12-Typeof pils1.3Design considerations
Most ACIstandards andmittee reports are gathered together intheanuallyrevised ACIManual of ConcretePractice (MCP).
inended for uidaplaing designing xting and ACI Commie Reports Guides and Commentaries areofindividuals warecmpetnt to valuale te signifcae insctingctThisdosndedrsand limitations of its coetent and remendations and who willaccerponsibliyforthe applicatof teatrial itcontainsTheAmericanConcreteInstitutedisclams nyand all resibiltyrhesadprncipleIttthllnot bliable fray lss or dmge arising terefrm.
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4.1General4.2-Loads and stresses to be resisted
Reference to this documemt shall not be made in contracttheArchiteEninebpart fthe ctrac dcmns documents. If items found in this document are desired byby the Architec/Engineer. tey shalersatedmndaorynuagefrincorpn
4.3Stractural strength design and allowable servicecapacities
4.4Installtio and service conditions affecting design4.5Other design and specification considerations
Chapter5Seismicdesignand detaling considerations p.27
5.2-General seismic impacts on pile bchavior 5.1-Introduction5.3Seismic pile behavior5.4Geotechnical and structural deignonsiderations 5.5-Seismic detailing of concrete piles5.6-Vertical accelerations
Chapter 6-Materials p.35
6.1Concrete 6.2Grout6.4Stel casing 6.3--Reinforcement and prestressing materials6.6Splices 6.5-Structura steel cores and stuhs
Chapter7-Manufacture of precast concrete piles p.39
7.2Forms 7.1-General7.3-Placememt of steel reinforcement7.5-Mixing transporing placing and curing concrete 7.4Embedded items7.7-Handling and storage 7.6-Pile manufacturing
Chapter 8-Installation of concrete piles p.43
8.1Purpose and scope8.3Prevention of damage to piling during installation 8.2-Installation equipment techiques and methods8.5Reinforcingstland stee coplac 8.4-Handing and positioning during installation8.6-Concrete placement for CIP and CIS piles8.7-Pilce details 8.8--Exraction of concrete piles8.9Concrete sheet piles
Chapter 9References p.57
sodau pue spes po6 9.2-Cited references
CHAPTER1INTRODUCTION
1.1-General
ground to support a load or pact the soil. They are Piles are slender structural elements installed in themade of several materials or binations of matcrials anddillingotngfthqlare difficult to summarize and classify because there are many types and new types are still being developed. ThisAmericnconsruction projct A pil tyecanbassgd repont coversonly the typesof pilescurrentlyusednNorth
a wide variey of ames or laifications by various agencie. codestchicaroupsandn varius ggraphicalrionsNo attempt s made herein to reconcile the wide variety ofnames used with a given pile type.
Piles can be described by the predominant material fromwhich they are made: stel concrete (or cement and othercnielyfslausually-stisornlledp of one material and a lower section of another. Piles madehoweverthrsteemmberscanueer pil tpiall d inopsllya itivemq pod ps sd the permanent water table. The design of steel and timberpiles is not considered herein except when used in conjuncpiles contain concrete or a cement-based material. tion with concrete.Most of the remaining types of existing
activated by air steam hydraulic r diesel'mechanism.although braty drivers areccasionally use ome pile destroydif tpdrvenFsch pils anital seelmanrl suchastughellndtwallesbis insered into the pile torxceive theblows of thehammerand support th shelduring installationThe pileis driven nto thground with the mandrel. which is then withdrwn. Driven
sdwith downward pressure instead of driving. Drilled piles usuallyvolveoncretorroutplacemet indirect contactgreater than that observedfor driven piles.On theother with the soil which can produce side-friction resistancehand because they are drilled rather than driven drilledpiles do not pact the soil beneath the pile tip and in fact can loosen the soil at the tip. Post-grouting may beuse afterinstallation to densify the soil under the pile tip.
Concrete piles are classified according to the condi-tion under which the concrete is cast. Some concrete piles(precast piles) are cast in a plant before driving. which allows controlled inspection of all phases ofmanufacture.Othr piles arecast-in-laceCIP).atemused in thisrepon to designate piles made of concrete placed into a previously-drivennlsedcontainerConcretefilled cougated shllsare cast-in-situ (CIS) a term used in this repor o designate and closed-nd pipe are examples of CIP piles. Other pilesconcrete cast directly against thc carth. Drilled piers and auger-grout piles are examples of CIS piles.
1.2-Types of piles
1.2.1 Precast concrete piles-This general classificationcovers both conventionally reinforced concrete piles and prestressed concrete pilesBoth types can be formed byextrusion and are made in arious cro-sectional shapes casting.spinning （centrifugal casting). slipforming.orsuchasriangularqr.tagol.drndmpiles arecast with a hollowcore.Precast pils sually have aunifom cross section but canhve tapered tip.Precasthanding and dvin sad. concrete piles are dsigned and manufactured to withstand
constructed of conventionallyreinforced concrete with 1.2.1.1 Reinforced concrete pilesThese piles areintemal reinforcement consisting of a cage made up ofindividual ties or a spiral. several longitudinal steel bars and lateral steel in the form of
constructed using steel rods strands or wires under tension. 1.2.1.2 Prestressed concrete pilesThese piles areThe prestressing stee is typically enclosed in wire spirals or ties. Nonmetallic strands have also been studied for usein piles (Sen et al. 1998a b 199a b) but their use is ncovered in this report.
d dddssdu casting beds. Post-tensioned piles are usually manufacturedin sections that are then asembled and prestressed to therequired pile lengths in the manufacturing plant or at the job site.
piles are either conventionally reinforced or prestressed pile 1.2.1.3Sectional precast concrete pilesThese types ofsections with splices ormechanisms that extend them to therequied lengthSlicestypicallyroide tefull ressive strength of the pile and some splices can provide the fulltesinngdstgtllyo and prestressed pile sections can be bined in the same pile for design purposes if desired.
1.2.2Cast-in-piace concrete pileGenerally CIP pilesmay be acorugatdmandr-driven stl ell pdriven or mandrel-driven steel pipe; allhave a closed end. Concreteis castinto theshellorpipeafer driving.Ths ulessitbecmesecessaryredrive the pilaft nreplacement the concrete is not subjcted to driving stresses.
The corrugated shells can be of uniform section tapered or stepped cylinders also known as step-taper. Pipe is also available in similar configurations but normally is ofuniform sction or a uniform upper section with a tapered lower section.
concrete placement. Reinforcing steel can be added full- length or partial-length as dictated by the design.
enlargement generally increases pile bearing capacity. One 1.2.3 Eniarged-tip pilesIn granular soils pile-tiptype of enlarged-tip pile also called a pacted concretepileis fomed by bom-driving a tue witha concrete plug to the desired epthThe concrete plug is then forcedthe base the tube is withdrawn while exanding concrete out into the soilas concrete is added. Upon pletion ofout of the tip of the tube; this forms a CIS concrete shaf.driven into the base and the tube withdrawn. The resulting Altetlypipercorrugatd shellsingcanbtmshell oree raarilletriallisadd tofl the ae annular space berween soiland pil）eitherclose onto theThe pile is then pleted as a CIP concrete pile. In either the CIS orCIP configuraion renforing stee can he addto the shaft as dictated by thedesign.
concrete hase in the shape of a frustum of a cone that is Another enlarged-tip pile consiss of a precast reinforcedgated shell or thin-walled pipe with the shaft and enlarged- attached toa pile shaftMost frequntly the shaft is a co-
tip base being mandrel-driven to bear in generally granular subsoils. There will be an annular space between the pileand soil as noted previously. The pile shaft is pletedas aCIPpilandeifrmet is addedasdictated byth design. Prcast nlargedpbaseshave alsbesedwthsolid shafts suh as timer pils.Precast nlarged-tip bass can be constructed in a wide range of sizes.
typefCPcnetepilthaisnstalledsigpcity 1.2.4 DrilleinisAdrilledin caisson isa secialunit carried down to and socketed into bedrock. These foun-ppudou apq p e sun uoep walled pipe o bedrock cleaning ut the pipe and drillingasocket into the bedrock. A structural steel section (caisson core) is insered extending from the bottom of the rocksocket to either the top or part way up the pipe. The cntireofthskn socket and the pipe are then filled with concrete. The depthand the nature of the rock.
consists of an oversized stee-tip plate driven by a slotied containing enough grout tformapile the sizeof the tiplate. steel-pipe mandrel. This pile is driven through a hopperThe grout eers the inside of the manrel through the lots as the pile is driven and is carried down the annulus causedby the tip plateWhen the rquired bearing isreachd hmandrel is withdrawn reulting in a CIS shaft. Reinforce- ment canbeloweredinto the grout shaft bforeinitialset ofthe grout. This pile differs from most CIS piles in that the mandrel is driven not drilled and the driving resistance canbe used as an index of the bearing capacity.
1.2.6 Composite concrete pilesComposite concretepiles consist of two different pile sections at least one ofthem being concrete. These piles have somewhat limited applications and are usually used under special conditions.The stuctural capacity of the pile is governedby th weaker of the pile sections.
Acmmcmpositpileismndreldvenugaldshell onp f n ut timepil ecialndiions at can make such a pile economically attractive are a requiredlong length an available inexpensive source of timberatable and a relatively low required capacity.
of a steelH-orpipe section witharinforedpont whee Anothermon posite pileis aprecast sectionontoppip l tiodddrn gd necessary. A CIP concrete pile constructed with a steel-pile. The entire pile (shelland pipe sections) is filled withconcrete and reinforcing steel can be added as dictated bythe design.
q Kapos poesu ae sad pad p L1dilling.Although driven piles can be predrilled the final operation of their installation is driving.
1.2.7.1 Cast-in-drilled-hole pilesThee pile alsoknownas drilled piersarestalle byehanicallyrilin aol tthqhnfiingtlewithrefror plain concrete. Sometimes an cnlarged base can be formed mechanically to increase the bearing area. A steel
liner is inseted in the hole where the sides of the hole are unstable.h linermay be left in place or withdrwn as thecncscdtltanqtobesrehatthcncrtehatdtineartins caused by th frictional fects f witdrawing the linerForcast-inll-hlepiles30in 760m） nd larent refer to ACI336.1-01
deep foundation units that ofien function like piles. They 1.2.7.2Foundation drilled piers or caissonsThese areare essentially end-bearing units and are designed as deepsondpods uo footings bined withconcrete shafts to carry the structurenotcoverdinhisreport;frmorenfrmatonfeC 336.1-01 and ACI 336.3R-93.
1.2.7.3 Aager-grot or concrete-injected pilesAuger-grout piles are usually installed by turning a continuous- light hollow-stem auger into the ground to the requiredpumped through the hollow stem. flling the hole from the depth. As the auger is withdrawn grout or concrete isbottom up.This CIS pilecanbe reinforced by a centeredfull-lengthbrlaced throughthehollowstemof theauger by reinforing steel to the extent it can be placed into thegrout shaf after letion or oth.
1.2.7.4 Drilled-displacemen pilesDrilled-displacementpilesare simlaroauger-groutpilesexcept that theugerslaterally and to eliminate orminimize soil removed by are designed to displace portions of the penetrated soilsdrilled-displacement pile augers typically have a larger the auger fights. As pared to auger-grout pile augers hollowstem pie larger ligh pitches and an unffigh displacement element or bulge to induce lateral-soildisplacement. Dependent on the design of the auger fightsand the section below the displacement bulge the piles may be refered to as either full- or partial-displacement piles. Ass gravity or pressure injection through the auger stem.
12.7.5 Drilled and grouted pilesThese piles areinstalled byrotating acasing havinga cuting edge into the soil reming the sil uttings bycirclaing dilling fidinserting reinforcing stcel.pumping a sand-cement grout through a tremie to filthe hole from the bottom up andwithdrawing the casing.Such CIS piles areused principallyass for underpinning work or where low-headroom conditionsoften installd through an existing foundation.
1.2.7.6Postgrouted pilesConcrete pilescanhave grouttbesddwithnmsthatfstallaintthe soil to consolidate the soil under the tip or both. can be injected under pressure to enhance the contact with
1.3-Design considerations
involvesinmt knwledgeofthrelevahical The sucesfldesignofaconcree pilefoundaiontransporta dealandlinstallnpr and structural design requirements. pile manufacture andproducing a satisfactory foundation. inspetinandcnrolf the pile installatin ae ssential t
unsatisfactorily due to: 1)bearing capacity failure of the Improperly designed pile foundations can performpile-soil system 2)excessve setlemntdu to cmpessionfailure of the pile shaft or its connection to the pile cap. and consolidation of the underlying soil: or 3）or stracturalIn additionimproperly designed pile foundations couid perform unsatisfactorily due to: 4) excessive settlement ormethods; 5) structural failure resulting from detrimental bearing capacity failure caused byimproperinstallationpileinstallaiproceuresorsutual filure relatedtenvironmental conditions.
Factors 1 through 3are clearly design-relatedFactor4and 5 are also design-relatd in that the designer can lessentinsandoiingptirdsdduring the instaltion process.Factor 6 refers to environ mental factors that canreduce the strengthf tepilhaftduring installaion or during service life.Thedesigner can consider environmental effects by careful selection ofdsto impederliminatethevironmental ffectsandmple sateforfturdtiortningoatngsrthmdmenting a periodic inspection and repair program to detect and correct structural deterioration. Hidden pile defectsproduced during installation can occur even if the piledesign maacturestallaion and ictina be flawless Davissonet al. 1983).Proper inspection duringdence of unforeseen defects. The design of the foundation manufacture and installation however can reduce the inci-pilinstalltsholdecrativefotbwenth system. preparation of the secifications and inspection ofstructural and geotechnical engineers.
pile installati is yond the oe f this rert althugh A detaileddiscussion of the procedures for monitoringdetermining the installation inspection procedures are noted some items that the engineer might want to consider inthroughout the text.For more detailed information on moni-cnces on pile inspection Davisson 1972b; Fuller 1983). toringpilstallntaesfdtral
suhsoil and the interaction of the pile-soil system under In the designof any pile foundation.the nature of theservice loads Factors I through 3）usually control the designto Factos4and5recovered inhater8although some andaredisussedinChatrs3and4.Considerationsrelatingguidancn these factorsas well asFactor 6isoffeedin Chapters 3 4 and 6 in connecti with the preparaton ofadeqateicalscifcWihfFaailefouatnfquralacityTdi specifcemmendsare giveninChaptr4nprovidingprocedurcnddaasednstivl obtained from theoretical considerations research data andgeneraldiscussnofsme golehicalandstrturl experiene withinservice erfomanceChaptr5pesentsdesign considerations that canbeimortant when piles areused in regions of high scismicity.
Apilccanbestrctrallydesignedadcnstrutdaflydt ered tohave achieved is required bearing capacity until it is
properlyinstalled and functioning as a part of an adequate pile-soil system.Thsin adition to its rquired designsqcapable of beinginstalled to their requird bearing capacity This necessitates having one set of structural considerationsfor driving and another fromal srvice.Usuallunderthe most severe stress conditions a pile will endure occur during driving.
defined:thefirst wo re strcturl innaturewhreas the Three limits to the load-bearing capacity of apile canbepileirsttilrivingstssescaxe os third depends on the ability of the subsoil to support thewill damage the pile This in tum limits the driving forceof the piagainst the soilandthreforetdvlopmn of the soil's capacity to support the pile. Second piles aredesigned to meet structural requirements under applicable loading conditions and codes with consideration given tothelatrldiidbil soilsholdbltsthpilladswithnauto failure it ssuallyeoil that giveswayand allw th with tolerle displacemets.I static pile load tests cadcan also occur. All three of these limits should be satisfied in pil toptratntthrond; pilshf fwee a proper pile design.
CHAPTER2-NOTATIONANDDEFINITIONS
2.1-Notation
A = pilecross-sectional area in.2 (mm²)A area of concrete(including prestressing stl） in=A-A forreinforced cncrete pilesin.(mm²) (mm²)A.. = area of core of section to outside diameter of the spiral stee in2 (mm²)A = grossarea of pile in.2 (mm²)Aa areafowintrveinfmet out-o-out of the renforcement in² (mm)Ap Ap =area of prestressing steel in.²(m²) = area of steel pipe or tube in.3 (mm)As = total area of transverse reinforcement in directionA are of spiralrtiebar in²(m) considered in.2 (mm²)As b = total area of longitdinal reinforcement in.2 (mm²) width of section in direction considerod in. (mm)de D datrftintsidf silinm） = stel shell diameter in. (mm)E =modulus of elasticity for pile material. psi (MPa =EI = flexural stiffnes of the pile Ib-in.2 (N-mm²) N/mm)s specife cmressi strength of concrtpsi (MPa) d=stress in prestressed reinforcement at nominal= yield stress of nonprestressed reinforcemen psi strength of member psi (MPa)fa = yield stress of transverse spiral or tie reinforce- (MPa)ment psi (MPa)f yield stress of steel pipe or tube psi (MPa)
f = yield stress of stee shll psi (MPa)( d o s = acceleration of gravity in/s (m/s)cross-setional dimension of pil core centr-to- center of hoop reinforcement.in.(mm)1 moment of inrtia of the pile section. in.(m)K 1 =moment of ineia of the gross pile section in (mm) horizontal subgrade modulus for cohesive sois. psiK = coefcie for determining effective pile length (N/mm²)L depth below grond surface topo of fixity.in (mm) = pile length in. (mm)=length of pile above ground surface in. (mm)= effective pile length = KZ in. (mm) = unsupported structural pile length in. (mm)M (N）= s = pile moment in.-Ilb (N-mm) standard penetration test N-vale scaled to a standardseoie d oa= coeficient of horizontal subgrade modulus Ibin.3 ffctive-vebunden pressureof 1 /t(96 kPa)P = axial test load on pile Ib (N) (U/N)P = allowable axial pression service capacity. IbPa allowable axial tension service capacity Ib (N) (N)R P. = factored axial load on pile Ib (N) radius of gyration of gross area of pile in. (mm)R = relative stiffessfactor for preladed clayin. mm5 s spacing of tie sets along lengh of mmbr in (m) = undrainedshear strength of soil In(kPa = kN/m)50 = spacing of hoops or pitch of spiral along length of member in. (mm)T = relative stiffnes factor for normally loaded clay. granular soils silt and peat in. (m)=walthiknes of stel shell.in(m）p = ratio of volume of spiral reinforcement to total volume of core (out-to-out of spiral) strength reduction factor = strength reduction factor in pression0. 0. = strength reduction factor in pure flexure flexurebined with tension or pure tension
2.2-Definitions
ACI provides a prchensive list of definitions throughan online resource “ACI Concrete Terminology” (hnp:/terminology.).
CHAPTER3GEOTECHNICALDESIGN CONSIDERATIONS
3.1General
In the design of any pile foundation the nature of thesubsoil the installation means and methods and the inter-action of the pile-soil system under service loads usually control theallwable pilodcapcityThispordestcover in detail the principles of soil mechanics and behavior as they can affect pilefoundation performance. This chapterdoes include however a general discussion of the moreimportant geotechnical considerations related to the proper
designof pilefoundatonsFormoredetailednfatinn geoechiclconsidertionsreferonralreferenensoilmechanics and pile design (ASCE/SEI 7-05;NAVFACctal. 1996). 1982: Peck et al. 1974; Prakash and Sharma 1990 Terzaghi
3.2-Subsurface conditions
the pile-foundation design and installation is eential.This Knowledge of subsurface conditions and theireffet onkowledgecanbainedfrmrioussouesnluingd existingfoundations under similar conditionskowledgeofgeologicalfomations gological maps soilprofls exposedin open cuts and exploratory borings with orwithout detiledsoiltests.Fromsuchinfmionlongwith knowledge of the structure to be supported and the character and magnitude of loading for examplecolumnchoice of pile type(s) lngth(s) and pile design oad(s) loadand pacing)it isoften possibl tomakea relimnry
On some projctsexisting subsurface data and priortin design with piledriving proceeding on the basis ofpenetration resistance depth ofembedmentor both.On other projects extensive exploration and design-stage piletesting can be required to develop final desig and installatin
Subsurface exploration cannot remove all uncertaintyabou susrface nditions on projcts with pile foundations Additional data on the actual extent of vertical and hori-zontal suboilvariations at a particular site canbebaind from fieldobservations during prodction pile istallation.Subsurface information collected by the desiger for useoften inadequate. in developing the design and monitoring pile installation is
pile-tip elevations that fall below the depth of the deepest Amnresult finadequate suburfaceexplorationisdatio wasntconsiderd whenexploratinstartedWhrasdeeper exploration will not prevent problems from devel-such explorations can be valuable in determining corrective oping duringconstructioninallcasesinformation fromadditional costf deeperexplorationuringthdsigntae options for solving those problems that do develop.Theis trivial pared with the costof a construction delayto base a decision. required toobtain additional subsoilinfomation on which
develophdecisioneapilefoatmd Inadequuburfcexloatifthdodd early in the design process. In such cases there often is abearingstramwhileobtainingnlyliteddanhevein is deimetal becausedesign paramterssuch as neativeskinfritiardedenteprpift lying strataFurthrmorea shortageoffomationn thdesignrandttactwaseinginsllon problemsassociadwithpenetrating theoverlyingstrata
andevalingttyefreactisytmmstcil for performing static load tests.
Test bringsshouldbemadeatoughlocatonsndtoa sufficient depth below the anticipatedtip levation of the piles to provide adequate infomation on all materials thatThe results of the borings and soils tests taken into consid- will affect the foundation construction and performance.deteing tpcinndlgthf pil tht sh eration with thefuctin f thepiles in service will ast inbe used and how the piles will be classified (for example types). end-bearing pile friction piles or a bination of both
po piso oq ues d yad q-g Ithe load is primarily transmitted to the soil at or close to material of high resistance to further penetration so thatthe bearing capacityof th soilrrockunderlying thepils the pil tip. The capacity of end-bearing pile depends nand the structural capacity of he pile shaft.etlment fbeneath the pil tips. piles is controlled primarily by the pression of materials
support fom the surounding soil primarily through the 32.2FrictiberingpilesAfrictionpilederivesisdevelopment of shearing resistance along the sides of the pile with negligible shaft loads remaining at the tip. Theshearing resstance canbe developed throughfrictionasimplied or it may actually consist of adhesion. The load capacityffrictinpiedpendsnthe abilityf theildistribute pil lads to thesoilbencath thepilgroup within the tolerblimits ofsetlemet f the sppredstctue.
32.3Combid friconndend-bearilCoidfictionandend-baingpildisbtpilds oithhrefldrestananntsf on the ilt the pil ipI this lficatnth te tive magnitude that one of them cannot be ignoed.
3.3Bearing capacity of individualpiles
thatheyare designed to carry the design service load with an Afundamnal dsignrqurement fall pilfoundatonsisadquate factorof safety against abearing capacity file. Usually.desigers deermine the factor ofsafey againsta bearing capacity flure that is nquired fo a particularproject alng with the foundatin loads pile type(s) and size(s） to be usedandan etimate of the pile lngthslikeyto be required. Design should consider the behavior of thetions thatshould be onsideed beyond the bearingcaacity entire pile foundation over the life of the structureCondiof an individul pile during the relatively sho-term instal- lation process are group bhavior lng-tem behavior andsettlement.
deqddsrequiremetsinstalltion procedures for individual pile.or both to conrol the actual construction of the foundations. Therfore dring constrction of the pile foundation designerenralyexercisesconolhsednthlod capacity of individual piles as installed.
the pile excoeds both the ultimate shcaring resistance of the An individual pile fails in bearing when the applied lad onsoil along the sides of the pile and the ultimate resistance ofthe soil nemath thpilepTheultimatbearing capaity of an individual pilecan be etermined most reliablyby staticload testing to filure.
Commonly used methods to evaluate the bcaring capacityof the pile-soil system inchude static pile load testing.static-resistance analyses. The resistance-to-penetrationmethods include dynamic driving formulas analyses based on the ne-dimensional wave equation and analyses thatuse measurements of dynamic strain and acceleration earthe pile head during installation. Careful judgment of an engineerqualified in the design and installation of pil foun-two ormoreof thesemethods areused to evaluate bearing dations is required when using these methods. Frequently capacity of individual pile dring design and cnstruction. For cxample static load tests to failure or proof-load tststo some multiple of the design load) may be performed ononly afewpileswith the remaning prodcton pileseng evaluated on the basis of a resistance-to-penetration method.calibratdginst th statld str
The design factorof safety against bearing capacityfailreof individul piles for apaticlar prjct epends nmanyvariables such as:
The type of structure and the implications of failure ofan individual pile on the behavior of the foundation. Buiking code provisions conceming the load reductionsapplied (for example loaded areas in determining theallowed for wind and earthquake conditions. structural lads applid to thefoundations or verloadThe reliability ofmethodsused to evaluate bearing capacity.The reliability ofmethods used to ealuatepile serviceThe construction control applied during installtion. loads.The changes in subsoil conditions that can occur with the passage of time.The maner in which soil-impod lads suchas negative skin friction are introduced into the factor of safetycalculations.Effects of pilelocation tolerances on pile service load. The variability of the subsoil coditions at the site.
capacity failure should not be less than 2. Consideration In generalthe design factor f safety against a bearingof the previously stated variables could lead to the use of ahigher factor of safety. When the pile capacity is based on analysis and not proven by static load tests the design factorfsed psnqnoaeso to static load tests.
3.3.1Lod testingStatic pile load testsremain themostreliable lforthegeotechical dsignof pilefoundation qdsddation desig incojction with the actual il fouatican be used to develop site-specific parameters for finaldesign criteria; make economical and technical parisons
of various pile types and design loads; verify preliminary design asumptionsincluding parisns or topof-pilemovements measured in the tests with those predicted bythe structuralanalyss;valuatespcilinstallaionmethd required toreach the dsired bearing strata and capacity: anddevelop installation criteria.
ddddintended eriffnal dsignasumionsstablishstlqualitynrlfthntlltipnbtdatf latin critriaatisfybuildingcodeeqremntsdevlevaluating unanticipated or unusual installation behavior.
Piles that are statically tested in conjunction with actualpile construction to meet building code requirements andfor quality control are gnerallyprof-loadedto two times the design service load. Where practical particularly fortests performed before final design pile load tests should be carried to soil-bearing failure so that the true ultimatetested canad asaferrmoreeconmicaedeignWithbrate other analytical tools used to evaluate individual pile- known failure loads the test results can be used to calibearingcapacitnotherareasof theprojcsite wheestaic load tests have no been perfomed.Futhermore knowledeof the failure loads aids evaluation of driving equipmentchanges and any changes in installtion or design criteria that can be required during construction.
dislose dissimilarities between soil conditions at the test-pile q pss locations and other areas where piles are to be driven. Theresults of a load test on an individual pile can be applied toprovided that the piles are of the same type and size and are installed using the same or equivalent equipment. methods andcriteria as that stalshed by thepile test.Fora pjt sitewithnrllysimilailndinughshldbe pefomed to establish thevariabilityincapacitycrosthesite. If a construction site contains dissimilar soil cooditions pile tests should be conducted within each area of generallyif the engineer can make this distinction. similar subsoil conditions or in the least favrable locatins
The results of a load test on anindividual pileare strictlyapplicalenlyat thetimef tht nduner dis of the test. Several aspects of pile-soil behavior can causefrom that observed during a load test on an individual pile. the soil-ile interaction in the pleted structure to differSome of these considerations are discussed in Sections 33.5through 3.3.8 3.4 through 3.7 and 3.10. On some projcts special testing procedures might be warranted to obtainmorecmprehensive dataforsenadressingtheinfuene of these considerations on the pile performance under load. e sd s
Isolangthil shafthung slssothat the pilcapacity is detemined wihin the baingInstrumenting the pile with strain rods (teltales) or material.gageso demine th disributinof load along th pile shaft.
