Chapter 1 Part 2 Substructures

8/18/2019 Chapter 1 Part 2 Substructures

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CHAPTER 1: SUBSTRUCTURECHAPTER 1: SUBSTRUCTURE1.2 Building foundation: types and

functions

1.2.1 Shallow Foundation - strip footings , pad footing, raftfoundation.1.2.2 Deep Pile/Foundation

- spun pile, icro pile, !a"au pile, !ore pileand pile cap1.# $olun stup, ground !ea and ground

sla!

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Wind load

Dead load

Wind load

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What is Substructure?What is Substructure?

FOUNDATION is a part ! SUBSTRUCTUREc"p#e#tsfoundation is the lowest portion of the !uilding

structure. %&tends fro the !earing surface to theain structure.'

(sually located !elow the ground le)el.

* foundation is a part of the structure which is indirect contact with the ground to which the loads aretransitted.

Foundations can !e located at+ !elow ground, at groundle)el, or a!o)e ground le)el.

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Shallow FoundationDeep Foundation

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Typical types of foundation

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Main functions of thefoundations

To supports the weight ofstructure and distribute theload of the structure over agreater area.

To transmit the loaduniformly under thestructure.

nchors the structure to the

earth! providing a "rm! leveland strong base over whichthe superstructure may beconstructed.

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Main functions of thefoundations

To avoid any settlement orother movement that cancause damage to any part ofthe building $a stable

foundation should bear theloads without sin%ing orsettling more than an inch atthe most&.

To increase the stability of the

structure by preventing itstilting or overturning againstwinds! earth'ua%es anduneven distribution of liveload $(ateral )tability&.

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Selection Criteria

(oading of the building!big load need bigfoundation such as raftfoundation or piling.

Types of soil such as peatsoil prefer piling or deepfoundation

+ost economical but

capable to supportnumbers of building orstorey $pad footing orpilling,&

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Selection Criteria The loads that must be transferred from the structure

to the soil strata supporting it. This also shouldevaluate the ability of the soil to support the ultimateloads.

The capability of the structure that will safelytransfer the loads from the superstructure to thefoundation bed.

The possibility and etent of settlement of the soildue to the presence of mines and 'uarries in the

vicinity. The possibility of the underground water has sulfates

or other salts that can degrade the foundationmaterials.

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Factors That Need To BeConsidered in the Foundation

Design)oil /nvestigation $)./& is needed to determine thesubsoil includes the soil type! strength! soilstructure! moisture conditions and the presence ofroots.

0urpose of )./determine the bearing capacity!seasonal volume changes and other possibleground movements.

ommon methods obtaining soil samplestrial pits!boreholes!window sampling anddynamic probe test.

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Designor more safety precaution use factor ofsafety FOS = 3

/ncrease number of bore hole or

sucient number of borehole so that theresult of the report is more accurate.hoose the critical point load for boreholevery end of the building

)upervise the )./ properly ma%e sure nomista%e

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Designor the safety of the foundation design usethe lowest of bearing capacity value.

The engineer must have good enough datafor the )./ such as previous soil report!cutting or "lling area.

ngineer also must ma%e sure the originalground level and purposed level orformation level while designing thefoundation.

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Design The correct parameter isimportant to prevent fromfoundation failure that may

occur causing building collapse./t will cause a big loss ofmaterial and even peoples life.

Shanghai-China

Highland Towers-

Malaysia

Overturning

residential building15


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Soil Quality Is The Key uilding rely on soil beneath to stay put. /f the soil under the house moves up!

down! or sideway! the house is in trouble. The soil pro"le may be varies as we move across from side to side! and when

we dig deeper downward. )trong soil wea% soil type range from

The following are the di8erent types of soils on which foundations are constructed9 Soft soils This soil is compressible and yields when loaded. amples are

clayey soil and loam. )mall buildings or ordinary structures can be built onthese types of soils.

Sreading soils These are noncohesive soils. amples of this type of soilare sand and gravel.

!ard or roc"y soils These are incompressible and strong soils. They canwithstand heavy loads without yielding. +ultistoried buildings and waterreservoirs are designed on such soils.

Bedroc-gravel-course sand-!ine sand-clay-silt-organic "aterial#STRONG WEAK

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Types of oundation

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SH$%%OW

FO&'D$T(O'S

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)trip oundation +ost suitable! economical type of

foundation for small building oncompact soil.

)trip foundation should bebuild:construct on soil with highbearing capacity.

This type of foundation is also %nownas wall foundation or continues spreadfooting foundation.

onsist of continuous strip of steelreinforced concrete! from centrally

under load bearing walls. The continuous strip serves as a level

base on which the wall is build and thewidth is design to capable to supportthe load without undue compaction.

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)trip oundationThe greater the bearing capacity of the

subsoil, the less the width of thefoundation.

;idth of strip foundations depends on

the bearing capacity of the subsoil andthe load on the foundations.


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haracteristic of )pread:)tripootings

(ow ostase of constructionor smallmedium si=e structures with

moderategood soil.or large structures with eceptionally goodsoil or shallow bedroc%.

)pread:strip footing may be built in di8erentshapes and si=es to accommodate individualneeds.

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Tyes of sread footings #ased onsi$e and shae

No Types of Spread Footings Applicable

1 Square for a single centrally-located column

2 Rectangular when large moment load are present

3 Circular for light standards, flagpoles etc

4 Continuous for bearing walls

!wall"strip footings#

$ Combined when columns are close together

% Ring for walls of abo&e-ground circular storage tan's

( Strap !cantile&er footing# when &ery close to a property line"other structure

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In both

situations shown

the thickness (T)

of the foundation

should be eualto ! o" #$%&&'

whichee" is

"eate"

T*! o" #$%&&

(whichee"

"eate") Foundation width

should not be less than

the appropriate

di"ension in Table )#*

Foundation width should benot less than the

appropriate di"ensions in

Table )#* plus o!!set

di"ensions $+ and $*

T T

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The !oundation !ails

where tension is

e,erted on the concrete

(! is greater than T. then the

!oundation "ay shear at /01

reducing the width o! the

!oundation and bearing area#

Following the shear !ailure. theload is concentrated on a s"aller

area. the ground "ay consolidate

under the increased load

Shear !ailure angle

/01

T

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ST%&&IN' ST(I&FO)ND*TIONS

;hen strip foundationused in sloping sitesstepped the foundation.

The full thic%ness of theupper foundation shouldoverlap twice twice theheight of the step$>?2T&! or 3-- mmwhichever is greater.

The bric%wor% andbloc%wor% on the top ofthe foundation should tiein at the step to avoid theneeds of cutting

bric%s:bloc%s and to avoidthe possibility of reducingthe stability of the wall.

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+ID% ST(I& FO)ND*TIONS

;ide strip foundations distribute loads over a larger

area and reducing the load per unit area on the ground.;ider strip foundation is most suitable for subsoil with

poor bearing capacity such as soft sandy clays.;idening and deepening the concrete foundation $to

ensure the foundation does not shear& @ uneconomical.lternativelyform a strip of steelreinforce concrete for

safeeconomical wide strip foundation $"gure #&.

Fiu"e +2 Wide Strip

Foundation

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N*((O+ ST(I&FO)ND*TIONS

lso %nown as trench "ll:deep stripfoundation.

)uitable for good bearing soil withseasonal volume change soil:clay e.g9sti8 clay.

The base of narrow:deep strip will

etend up to a depth where the clay soilis una8ected by seasonal changes inmoisture content.

5-mm thic% compressible sheetmaterial may needed to prevent lateralpressure to the sides of the foundation$saturated and dries out condition causeepansion and contraction of soil at theeternal face of the foundation&

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(ectangular SreadFootings

/t have plan dimension of B x L! where L is the longestdimension.

These are useful when obstructions prevent construction ofa s'uare footing with a suciently large base area andwhen large moment loads are present.

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Circular Sread Footings

This foundation areround in plan view.

These are morefre'uently used asfoundation for lightstandard! Aagpoles! andpower transmission line.

/f these foundation

etend to a large depth!they may be have moreli%e a deep foundation.

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Continuous SreadFootings This type of foundation is also %nown as wall

foundation or strip foundation.

/t uses is to support bearing wall.

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(ing Sread Footings

This footing are continuousfooting that been wrappedinto a circle.

This type of footing is

commonly used to support thewalls of aboveground circularstorage tan%s.

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orces pushingdown must e'ualthe forces pushingup %Q)I,IB(I)M

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Beave

)ubside

/f the forces pushing up isgreater than the forcespushing down the building will

be pushed upwards @ !%*-%

/f forces pushing down isgreater than the forces

pushing up the building willsin% @ S)BSID%NC%

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0roblems if the rules arenot followed

$0CT&

The load spreads atabout 4-- through thefoundation

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,oads *cting on the


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,oads *cting on the

Foundation The foundation has to bear more than Dustthe load of the superstructure.

load can be de"ned as anything! whicheerts pressure or thrust on a structure.

The following are the di8erent types ofloads that act on the building foundation9

,i.e ,oad /Q" 0 live load or imposedload is a movable! temporary ortransferable load. This can includemoving vehicles! people wal%ing orchildren Dumping.

Dead ,oad /'" 01 This load is permanentand immovable. /t is the non transferableload of the structure itself.

+ind ,oad /+" 0 This load is applicablewhen the structure is tall.

Sno2 ,oad This load is consideredwhen the structure is situated in snowy!hilly areas.

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3oc or soil Typical bearing value4'5"*6

Massive igneousbedroc

Sandstone

Shales and "udstone

7ravel. sand and gravel.co"pact

Mediu" dense sand

%oose !ine sand

Hard clay

Mediu" clay

So!t Clay

+8.888

*.888 to /.888

988 to *.888

988

+88 to )88

%ess than +88

)88 to 988+88 to )88

%ess than :0

Typical allowable bearing values37


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&*DFO)ND*TIONFOOTIN'

)imilar to continuousfootings accept for they areusually lain under a singlepier:column.

0ad foundation spread theload out $in a s'uare& withthe column:pier sitting inthe middle of the s'uare.

an also be designed forloads of the walls and thebuildings are transferred

through ground beams thatrest on the pad foundations. The pad foundations the will

transfer the loads to a lowerlevel where soil of sucientload bearing strata eist.

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onstruction se'uence of pad foundation

Mared out and e,cavate

ground to correct level#

;,cavation level should up

to good load bearing

strata#

The clean and leveled

ground then poured with08"" thicness lean

concrete#

For"wor !or the !ooting

installed at the correct

position

(nstall rein!orce"ent according

to construction detailing

$!ter pad !ooting detailing

inspected and approved than

concrete can be poured and

leave the !oundation to dry

4curing process6

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&*DFO)ND*TIONFOOTIN'

The advantage of thissystem of foundation isthat poc%ets of tippedstone or bric% and

concrete rubble that wouldobstruct bored pile may beremoved as the pits areecavated.

The nature of subsoil alsomay be eamined as thepits are dug to select alevel of sound subsoil.

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S4uare Footings

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Co5#ined FootingFoundation

/n this type! the two wallsor columns of asuperstructure are providedwith a single combined

footing. This is designed so that the

center of gravity of thesupporting area is inproportion to the center of

gravity of the tow columnloads.

These can be rectangular ortrape=oidal in shape.

These are usefull whencolumns are located tooclose together for each tohave its own footing.

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(*FT FO)ND*TION

Eepending on its positionraft foundation also %nownas +at foundation inAoating position.

)ometimes also called as

loating oundation.Fsed where heavilyconstructed loads are to bedistributed over a largesurface area.

/t is used where the soil ismarshy! clayey or soft!with wea% bearingcapacity.

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This consists ofreinforced concrete

slabs covering theentire area ofconstruction! li%e aAoor.

lways made ofreinforcedconcrete.

SI,!-E RAFT FO.N/ATION

RAFT FO.N/ATION

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(*FT FO)ND*TION

/f groundpressures areli%ely to be

ecessive atdi8erent seasons!reinforcementmay be re'uiredthis is %nown asfa#ric when in

sheet mesh form.

REINFOR0E/ RAFT FO.N/ATION

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0onditions fo" Raft1,at Foundations-Structural loads re


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D%%P F(D*

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DEEP FOUNDATIONDEEP FOUNDATION

0easons why Deep Foundation

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ain $oponents of Deep Foundation

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DEEP FOUNDATIONPiles are long and slender e!ers which transfer

the load to deeper soil or roc" of high !earingcapacity a)oiding shallow soil of low !earingcapacity.

he ain types of aterials used for deep pilesare wood, steel and concrete.

Piles ade fro these aterials are dri)en, drilledor 3ac"ed into the ground and connected to pilecaps.

ain functions of a pile+i. to transit a foundation load to a solid ground

ii. to resist )ertical, lateral and uplift load

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Factors (n!luencing


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g

The Choice o! ile

%ocation and

Type o! Structures7round Conditions Durability Cost

7round containing

Boulders-

clay with

ground heave

%oose water

bearing sand

Concrete

Steel

Ti"ber

(nstallation costOver water

On %and

'ot causing vibration

to e,isting5nearby

Structures-

Heavy Structure

;,isting Structure

&nder-rea"ed bases

"aterials

ti"e

Test load

Supervision

Organi>ation.

overhead and etc#53


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Factors nfluencing the $hoice of Pile

$cati# a#% t&pe ! structures

For structures o)er water, such as whar)es and 3etties,dri)en piles or dri)en cast-in-place piles 4in which theshell reains in place' are the ost suita!le.

n land, dri)en cast-in-place types are usually thecheapest for oderate loadings.t is necessary for piles to !e installed without causing

any significant ground hea)e or )i!rations !ecause oftheir pro&iity to e&isting structures, the !ored cast-

in-place pile is the ost suita!le.For hea)y structures e&erting large foundation loads,large-diaeter !ored piles are usually the osteconoical.

5ac"ed piles are suita!le for underpinning e&isting

structures.54


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'ru#% c#%iti#s

Dri)en piles cannot !e used econoically in groundcontaining !oulders 4large roc"s', or in clays when

ground hea)e would !e detriental.Bored piles would not !e suita!le in loose water-

!earing sand, and under-reaed !ases cannot !eused in cohesion less soils since they are suscepti!leto collapse !efore the concrete can !e placed.

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Durabi(it&

ost iportant criteria especially in the choice ofaterial. For e&aple, concrete piles are usually

used in arine conditions since steel piles aresuscepti!le to corrosion in arine conditions .

ti!er piles is not the ost suita!le type underarine conditions !ecause it can !e attac"ed !y

!oring olluscs .n land, concrete piles are not the !est choice,

especially where the soil contains sulphates or otherharful su!stances.

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$ost

$onsidera!le iportant decision o)er the choice of pile.

he o)erall cost of installing piles includes: the actual cost of the aterial,the ties re6uired for piling in the construction plan,test loading,cost of the engineer to o)ersee installation and

loadingcost of organisation and o)erheads incurred !etween

the tie of initial site clearance and the tie whenconstruction of the superstructure can proceed.

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$lassification of Pile 7ith 0espect to 8oadransission and Functional Beha)ior

nd bearingpiles $point

bearing piles&riction piles

$cohesion piles &ombination of

friction andcohesion piles

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%D B%*09 P8%

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%nd !earing piles ypical end-!earing piles are dri)en

through )ery soft soil, such as a loose silt-!earing stratu underlying !ycopressi!le strata.

his pile acts on the !asic concept ofdigging through the top soil 4relati)elywea"' to an underlying firer roc" toanchor the foundation.

he piles transfer their load on to a firstratu located at a considera!le depth!elow the !ase of the structure.

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%nd !earing piles

his pile !eha)es as an ordinary colun. n wea" soil, this pile will

not fail !y !uc"ling

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%nd !earing piles-cast in place

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%nd !earing piles - dri)en or 3ac"ing40.$ or Steel Pile'

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Piling 0ig

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Pile Dri)ing65


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F0$ P8%

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Friction piles

Friction piles, also "nown asfloating pile foundations, $oonly used in

construction to pro)ideunderground support for!uildings, !ridges, doc"sand other structures.

hey are often used whenend-!earing piles are notsuita!le.

Friction piles relyspecifically on the frictioncreated !etween the soiland the surface of the pile

aterial in order to pro)idesta!ility. he co!ination of friction

and adhesion with the soilcauses the to stay inplace.

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F i ti il


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Friction piles

he load is transferred tothe ad3oining soil !y friction!etween the pile and thesurrounding soil.

he load is transferreddownward and laterally tothe soil.

n order for friction pilesto !e effecti)e, the soilsurrounding the area ust!e fairly unifor in typeand density.

For ore cople&situations, construction

copanies soeties relyon a co!ination of frictionand end-!earing piles.

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Friction Pile ypes

0ast2in2situ

/"ien

lace"ent

o! pile

(nstallation

o! ile3epetition

process

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SP( P8%

7-

S Pil


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Spun PileStandard $haracteristics Pre-stressed concrete spun pile 4cast in the factory' and deli)er

to site for installation. Si;e : 2, ? and 12 4ypical'

Structural $apacity : @


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Spun Pile

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Spun Piles Es. 0$ S6uare Piles

Spun Piles ha)e Better Bending 0esistanceigher *&ial $apacity Better anufacturing Guality *!le to Sustain igher Dri)ing

Stressesigher ensile $apacity %asier to $hec" ntegrity of Pile

Siilar cost as 0$ S6uare Piles withhigher pile integrity

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d A D d f P l


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*d)antages A Disad)antages of Spun Pile

No Advantages Disadvantages

1 Best suited for use as friction piles that Expensive to splice and cut

don't meet refusal during driving

(refusal: pile can't be driven any further so

it becomes necessary to cut off the portion!

" Best suited for toe#bearing piles $here the Difficult to cut

re%uired length is uniform and predictable

& ess expensive than steel piles usceptible to damage during handling

or driving

) *ave a large load capacity Not suited for hard driving conditions

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B0% P8%

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d l


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Bored pilesH Foundation structure ade of

reinforced concrete on site.H (sed to carry hea)y loads !ytransitting the load to a sta!le soilstrata.

H Earies in diaeter and depth.H Diension )aries fro @


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Bored Pile $onstruction

H Bored piles is constructed!y first drilling a hole inthe ground until acopetent load !earinglayer is reached.

H nce achie)ed, areinforceent steel cageis lowered into the drilledhole and the hole is filledwith concrete.

H t is also "nown as cast inplace piles)

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B d il


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Bored piles igh fle&i!ility and are widely used in

deep foundation for :- high rise !uildings, 3etties, !ridge foundation and as )ertical retaining structures li"e a

retaining wall or sheet piles wall. 4n thiscase the !ored piles is "nown ascontiguous !ored pile wall'.

Designed either as a point !earing pilesor friction piles.

f copetent load !earing layer li"e!ed roc" is present, then the !oredpiles will !e designed as an end-!earingpile. his eans that the load carrying

capacity of the piles is ainly deri)edfro the !earing capacity of the roc"layer at the toe of the pile.

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Bored Piles


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Bored Piles

Bored pile-single pile - pile groups.

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can !e inclined to a certain angle.*ngle !ored piles also "nown asra"ed piles 4found in structures thatre6uires resistance to hori;ontalload li"e in a retaining wall or !ridgeand piers foundation'.

7hen !ored piles are

constructed close to oneanother or o)erlapping slightly,this is "nown as contiguous!ored piles wall or secant pileswall.

#-

Sta#%ar% Bre% Pi(es Characteristics

Si @


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Si;e : @


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#2


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#3


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#4


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#5


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#6


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#7


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##


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#*


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*-


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*1

*d t A Di d t


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*d)antages A Disad)antagesBore Pile

No Adantaes /isadantaes

# -ess costs of &obili3in and de&obili3in a d"ill "i /e4endent on cont"acto"5s skills

6 -ess noise and ib"ation -owe" unit end bea"in ca4acit7

8 Soils e9caated can be obse"ed and classified E94ensie fo" full2scale load test

du"in d"illin

: Si3e of shafts can easil7 be chaned du"in const;

$ 0an 4enet"ate soils with cobbles' boulde"s and

&an7 t74es of bed"ock

< !ossible to su44o"t each colu&n with one la"e

shaft (no 4ile ca4)

*2


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$0P8%

*3

icropiles

Si;e : 1== to #


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Si;e : 1== to #


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icropiles

icropiles also "nown ini piles.*pplication also for foundations of a wide )ariety ofconstruction pro3ects such as highways, !ridges ande)en transission towers.

$an !e installed at )arying angles i.e. fro )ertical to

o!tuse 4angle !etween ?=-1= degree incline'.ighly capa!le of resisting !oth lateral and a&ial loadsdue to the fact that they are ade of steel with)arying diaeters of !etween I= to 2== .

Sheer a!ility to pro)ide a co!ination of !oth tensile

and copressi)e resistance, icropiles tend to !e6uite useful where there is a need for resistance touplift.

Eery little or no )i!ration at all.

*5

echnological process of carrying


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g p y gout icropiles

2a& reali=ation ofa boreholewith the rotarytechnology

2b& pulling outdrilling toolsand "lling the

hole with grout2c& setting areinforcementthic%walledsteel pipe

2d& grouting ofthe micropile

root part2e& "nished

micropile

Pressure+,rute% "icrpi(es c#structi#

*6


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E9a&4les of unde"4innins of e9istin

st"uctu"es with the use of &ic"o4ile s4ace4ie"s o" indiidual &ic"o4iles

Secu"in oe"bu"dens of unde""ound wo"ks

(tunnels' alle"ies) with the use of a

&ic"o4ile u&b"ella

Carrying out pipe "icropiles to protect the driven

tunnel calotte. the 'ew Connection in rague*7


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*#

ast insitu micropile


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as s u c op econstruction

**

! /B " P l


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i!er/Ba"au Pile

i!er is a hugely capa!le ci)ilengineering aterial, with theadditional ad)antage of !eingsustaina!le.

rees, in particular conifers, a"enatural piles.

i!er foundations ay !e particularlysuita!le for countryside structuressuch as !ridges, forest chalets andacti)ity centres, as well as post-and-!ea ti!er !uildings in waterfront or

flood prone locations. Preser)ati)e treated softwood or

dura!le hardwood ti!er can !e usedfor the construction of retaining walls,!an" seats, and for foundation padsand footings.1--

! /B " P l


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i!er/Ba"au Pile For any structures, ti!er piles are a highly suita!le choice of

foundation, gi)en appropriate ground conditions. hey are econoical, easy to transport, handle, cut to length and

wor" with on site+ and particularly suited for locations with accessdifficulties, or where e&ca)ations and the deli)ery of concretewould pose pro!les.

Short, dri)en ti!er piles can !e the solution for foundations inground with a high water ta!le, and where fir strata e&ists !elowsurface aterial of loose sand, soft clays, or organic soils.

1-1

i ! /B " Pil


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i!er/Ba"au Pile n deep silt deposits, where the capacity of the pile is deterined

!y shaft friction, ti!er piles are especially suita!le !eing taperedand easy to splice.

i!er piles are suita!le to !e used !elow the water ta!le, wherethey ha)e pro)ed practically in)ulnera!le to decay, and e&tended tothe surface using concrete sections.

hey are resistant to acidic and al"aline soils, and soils with highsulphate or free car!on dio&ide content.

i!er piles can also !e dri)en for ground ipro)eent, to densityloose granular soils.

For the decay reason-treated with preser)ati)es such as creosote

oil which ipregnated into the wood 4pre)enting dry-rotting andagainst daage fro ost anial and plant attac"'

1-2

i ! /B " Pil


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i!er/Ba"au Pile he installation of ti!er piles is a process that in)ol)es dropping a

weight on top of the pile in order to dri)e the pile into the ground. i!er piles ha)e !een used for centuries to support an-ade

structures. he e6uipent that is used to install ti!er piles includes a crane,

a !oo, a set of leads, a haer, a helet, a pile gate, pile on"ey,

and pile 4see Figure'.

1-3

*d)antages A Disad)antages


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g gBa"au pile

No Advantages Disadvantages

1 Low construction cost Medium axial loads 1!! " #!! $N%

& 'sed as waterfront structures Susceptible to decay

( For lig)t driving conditions Susceptible to damage w)en driving

in loose sands and soft to medium clays%

1-4

Pili h i


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Piling echni6ues

Eamage during driving can becontrolled by using propertechni'ue.

mong the soultions are9GFsing lightweight hammersGFsing steel bands near butt

GFsing a steel shoe on the toeG0redrilling

1-5

D ill d % i t


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Drilled %6uipents

Dri((i#, Ri,sruc"-ounted

drilling rigFor usual

shaft,dJ.2@

Speciali;edrigs

*-ShapedFrae 0igs

1-6


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Dri((i#, T(s

he heli&-shaped flight auger4ost coon used') %ffecti)e in ost sols and

soft roc"s *ugers with hardened teeth

and pilot stingers

) %ffecti)e in hardpan oroderately hard roc"

Spiral-shaped rooting tools) elp loosen co!!les and

!oulders

1-7


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Buc"et augers) o collect cuttings in a cylindrical

!uc"et) (sed in running sands

Belling !uc"ets) o enlarge the !otto of the shaft

4!ells or under reas' $ore !arrels

) o cut a circular slot creating areo)a!le core

) (sed in hard roc" ulti-roller percussion !its

) o cut through hard roc" $leanout !uc"ets

) o reo)e final cuttings fro hole

Belling bucet

Bucet augers

1-#

D ill d h i


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Drilled echni6ues

Erilling in irm )oilsFsing dry method $openhole method&+ost common used9 simple! economy and

good reability

)teps9Boles usually advance using conventional Aightauger

Boles remain open without any special supporthec% the open hole for cleanliness and

alignment/nsert steel reinforcing cage0our the concrete

1-*


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11-


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Drilling in $a)ing 4$a)e-in' or S6uee;ing Soils

$a)ing:he side of a hole which is collapse !efore or during concrete

placeent.(sually in clean sands !elow the groundwater ta!le.

S6uee;ing:

he sides of hole !ulging inward during or after drilling(sually in soft clays and silts or highly organic soils.

ost coon techni6ues:(sing casingDrilling fluid 4slurry ethod' using !entonite clay or

attapulgite clay.

111


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P8% $*P

112

P8% $*P


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Pi(e Cap 4BS ==@', Ka pile cap is

defined as a concrete !loc" cast onthe head of a pile, or a group of piles,to transit the load fro thestructure to the pile or group ofpilesL.

H Pile cap transfers the load for thestructures to a pile / pile group, thenthe load further transfers to frosoil.

HPile caps are thus incorporated in

order to tie the pile heads together sothat indi)idual pile o)eent andsettleent is greatly reduced. hesta!ility of the pile group is greatlyincreased.

P8% $*P

113


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114

Foundations relying on dri)en


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Foundations relying on dri)enpiles often ha)e groups of pilesconnected !y a pi(e cap 4a

large concrete !loc" into whichthe heads of the piles aree!edded' to distri!ute loadswhich are larger than one pilecan !ear.

Pile caps and isolated piles aretypically connected with ,ra%ebea"s to tie the foundationeleents together+ lighterstructural eleents !ear on

the grade !eas while hea)iereleents !ear directly on thepile cap.

115

Pile *rrangeent !elow pile cap


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Pile *rrangeent !elow pile cap

116

Pile cap


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Pile cap

Function:o distri!ute the structural loads to the piles.o tie the piles together so they can act as a unit.

o laterally sta!ilise indi)idual piles thus increasing o)erallsta!ility of the group

o pro)ide the necessary co!ined resistance to stresses setup !y the superstructure and/or ground o)eent

117


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$8( S(P

11#

$olun Stup


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$olun Stup he stup is the siplest and ost failiar

footing used for the )ertical support and thetransfer of !uilding loads to the foundation. Stups are used to support ti!er-fraed

houses for which they are currently the ostcost effecti)e.

hree types of aterials are coonly used forstups: ti!er concrete steel.

Stups ust ha)e a concrete or ti!er footingplaced underneath the !ase of the stup. his isto spread the load transferred to the stup

fro the !uilding. his support !eneath thestup is called a MpadM or MsoleplateM. (sually concrete stups are pro)ided with

concrete pads poured i# situ on the site. i!erstups are pro)ided with ti!er soleplates.

11*


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90(D B%*

12-

2 1 90(D B%* *D S8*B


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2.1 90(D B%* *D S8*B Beas and sla! are norally naed !y

its location. 9round !ea refers to the structure of

!ea located on the ground. 9round Beas are designed to support

!ric"/!loc"wor" or to for a peranent

shutter to the edge of in-situ concretefloor sla!.

he aount of reinforceentintroduced into the design will !e usedto suit specific loading re6uireents

and the !eas can !e designed towithstand any hea)e forces with the useof )oid foring or copressi!leaterials.

121

rdinary 9round Bea


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rdinary 9round Bea

his type of ground !ea is the ostused in !uilding construction.

t is the !ea which !oth its ends aretied up at the colun and lying !etween

the two colun. he !ea fi&es and holds fitly the

coluns in order to sta!ili;e it. n addition, it also acts to !ear all the

loads coe fro the wall which

constructed parallel with the !ea.

122

0D*0N 90(D B%*


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0D*0N 90(D B%*

123

* ground !ea norallyshould consist of followingites+0einforceents,$oncrete,8in"ers

he reinforceents can !eplaced at center of that!ea.

he si;es of ainreinforceent playiportant role in deterinethe strength of a !ea.

9round !ea usually doesnot ha)e secondary !ea,only has priary !ea.

0D*0N 90(D B%*


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0D*0N 90(D B%*

124

90(D $*8%E%0 B%*


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90(D $*8%E%0 B%*

125

he functions of groundcantile)er !ea are alost sae!ut it cannot !ear the loadingsuch the ordinary !ea. his is!ecause, one end of that !eais not holding !y any structure.*s a result, it does not achie)esthe strength li"e the ordinary!ea

?he cantile)er !ea is sae as the !ea e&plained !efore !ut onlyone end of cantile)er !ea is tied up at the colun stup. heother end is free without 3oint with any colun.?he cantile)er !ea usually used for e&ternal structure such as!ea for corridor and also partition wall outside the !uilding.

Bea $onstruction ethod


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Bea $onstruction ethod

126

he ground !ea construction will !e started after acolun stup has finish. 4*fter the colun stup hasingrained in foundation and has corpulent on le)el aswanted'.

Bea forwor" will put and pointed sta"e set in theground with tidy so that loo" tough and strength.

Strength of forwor" is iportant to ensure thatforwor" not e&pand when a concrete will instill. fforwor" not good, its will gi)e a pro!le and theconstruction wor" ha)e uch tie.

*fter that, lin" concrete is lain out on ground surfaceinto the forwor". he reinforceents will !e putted

with spacer !loc" on !elow and !eside reinforceent.Purpose that putted the spacer !loc" is to protect thereinforceent for a)oid fro rust


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127

R)C) BEA- CONSTRUCTION PROCESS

9round Bea


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9round Beahe ground !ea construction procedure 41= steps'+

1. clearing the ground.2. he span !etween the coluns or piers is raed and copacted.#. * !linding layer is done with 6uarry dust.@. he colun or pier reinforceents should !e left a foot high to 3oin

with the !ea.. nce ready, they are carried and laid o)er the coluns and !linding.I. he reinforceent is laid straight with spacer !loc"s put at the

!otto.. nce the !ea steel is in place, for wor" is erected to the sides.

hese ust !e fired into the ground and ade )ery tight. his willpre)ent the escape of the ceent slurry when )i!rating.

?.*fter the for wor" is coplete, concrete is prepared and pouredinto the fors. he process continues while )i!rating to ensure theconcrete is well !onded with the steel.

1=.he top is taped to !e sooth. he fors are reo)ed after se)endays while curing.

12#


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90(D S8*B

12*

9round Sla!


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9round Sla!

13-

n construction, sla! can !e design in two conditions.

N#+suspe#%e%s(ab

Suspe#%e% s(ab

9round Sla!


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9round Sla!

131

9round Sla!


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9round Sla! Function of ground sla!:

o support colun and stupo recei)ed the load fro the !uilding o reduce the pressure on the colun and stup he ain !ase of construction to ensure that the

construction will done well$reate the easier 3o! on floor finishes

he construction of a solid ground sla! floorshould includes:

ardcoreBinding$oncrete !ed or sla!

132

9round Sla!


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9round Sla!

ardcore he purpose of hardcore is to fill in any sall poc"ets that ha)e

for during o)er site e&ca)ation, to pro)ide fir !ase on which toplace a concrete !ad and to help spread any point loads o)er the

greater area. t also acts against capillary action of oisture withinthe soil. ardcore is usually laid in 1==-1


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9round Sla!

Binding his is used to e)en off the surface of hardcore if a dap-

proof e!rane 4DP' is to !e place under the concrete !edor if a reinforced concrete !ed is specified.

First, it will pre)ent the dap-proof e!rane fro !eingpunctured !y the hardcore and, second, it will pro)ide a truesurface fro which the reinforceent can !e positioned.

Blinding generally consists of a layer of sand 2


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9round Sla!

$oncrete !ed (nreinforced or plain in-situ concrete, 1==-1


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136

$oncrete 0einforceent esh

9round Sla!


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9round Sla!

137

41' Dap Proof e!rane 4DP'7ater penetration is a prie cause of deterioration in

!uilding structures and aterials and the presence ofe&cess oisture encourages the growth of oulds and woodrotting fungi. Because of this, !uilding regulations re6uirethat !uildings are so designed that water neither daagesthe fa!ric nor penetrates to the interior where it ayconstitute a health ha;ard as well as spoiling decorations.

ther aterials needed for ground sla!:

9round Sla!


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9round Sla!ther aterials needed for ground sla!:

42' Dap Proof $ourse 4DP$'DP$ is a physical !arrier inserted into the fa!ric of a !uilding

to stop water passing fro one place to another. his can !e on

a hori;ontal plane, stopping water rising up fro the ground !y!eing suc"ed up !y the dry asonry a!o)e, or )ertically to stopwater passing fro the outside of a !uilding, though theasonry, to the inside. DP$Ms ha)e ta"en any fors throughthe ages and one of the earliest fors was to use a layer ofslate in the construction. Slate is still used !ut the lesse&pensi)e plastic )ersion 4 !elow right ' is now ore widelyused.

13#


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%D F $*P%0 1

Than% you

Chapter 1 Part 2 Substructures

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Transcript of Chapter 1 Part 2 Substructures