IT{TBOI'UCTION TOCOIIC* TE DE|SIGITI

TO EUBOCIODE

. Rc ls one of the prtncipal materiels useerEirerintr applicatior.

many ciuil

Civil Eng. Application :. co6struthn of bltildrg; tltaldrg ffitls, bsn&lons, ffiter

rctilntls strudures, hEhura, and kidtEc

It b a cornposit m*Brial, coasistirEof steel reinforcing bar$ernbedded in a hardcned oierete matrix.

These tro mabdals have cgmplemefttary pmperti*.

ooclrrnert that gives recornmendation for the design andconstructlon of stru*sn*.

It containa detalled requirerrent regardlng actions, suesses,design principal and method of achieving the

requird performarre of compleEd structure.

Th deiign prgcedures, d$ribed in this course conform to&e iotlowing Eurocode {EC} published by EuropeanCoffinitte {or Standardzation.

Concrete i. Highly in compressive strEfig$ butweak in tensile

strength.

Rsinforcement (ste6l) :. Hrghly in tensile strengtfi butweak in oonrpreeslve

strength.

By providing staal bars in the zones within aconcrete member which will eubjected to tonsilestresses, an econilnicd structural material ean beproduced through ils composite action.

r ln addition, the concrcte gwides cororion protectior andfire rerisance to th embeddd steel reinftrcing bas.

ffit EN199O Eurorode& Ba*sofskucirrrald*kat EN1S91 Eurocodcl: Astontslstrus$retI Elt1992 Eurocode2: DgBnofconsetestrucnrtes

. Eurocode 2 (ECll applies to the deeign of buiHings and ctuilnginedng works in plain, reinfurced ald ptEtrcssdconciete. EC2 cornes in several parts as follolt|r:

ENlggzPartl-2 &iBafdiiEtus--Sbstud,lt6{*xibnEN imz H 2 C@cdc bddgE -d!S!i!d #amng ilbseru tggZ Part a Liqut rAarrim and ontaillmrt 8lrudre

r fhe purpose ol design is to aehiare acceptable probabilitiesthat . structure will not h@{rre IEEi fur it iAtended use.That ls, that it will rd readr 5 limit 3tate.

t At an? way in which a stfirctut may ce-as !o b fit for U3will constitute a lirnit stah a*d tie design aim is to avoidany such ccndition being rcaded during the expected liia ofthe strueture

. Thre arc trvo prlncipal types of limit state:r lrltimate limit state. SeMceability limit state

t siE r sittlations of limit state

bl\*"n'*.nd.m$'kAtridentelqrirlLf^

OeslSn rfhrat on dudnt a Fedod of the emedder s dlc deCan mrldnt llh o, the rtructure.ieprcsrtsrmleHSn edar durerg a p.rbd eurdr CErt rdun tl* dc{n rcrldng lite ot the stn ctu r,c.& dudi( *Gllt!o!. o{ reFlrDedln Cluatlon imMnt erccptional condltlonsfor structurc. e,& aire, Gxplclon, imp3cl e&Defitn situ.tion imMng dceptlonrl ronditions!o. structre during *iffiic eEnt.

. For prsistent and transir* design situ*isr onder the $TRlimlt state, the Euruode defines threa possible ombinationas follows;

L S.&!ffi6:4a5.t&d6edhb&Me2. tuTdElelq*cqGt&.roe@ea?dBe

.!r,{@turdBc&G&dt!&rr-Ltg- rd-l.G rs-,$#llffiG#i@ttq -8tuffi6*c@ E-o.6

Condition in which th strucare is damaged and uns{itable6or its intend purposes causirg dis.omfort to thc occupants.Genenllythe most importafi servkeahility limit state are:r Defieftion fhe ,poctreno. ct efEdency of Ery prrt of the

structsrc mr.st llot h advefsely afMed bydenectkri.

r CBddng foal de[Ese Are to cddng and spalllng mltstnot effEct ilre ap?eaancs, e-fffdmcv or durabiftyof the stEEllB

other limlt statEs whlch Imy be nrached includedconsideration of durability, vibration and fire resistance ofstiuctores.

The charactsristic srength /* is the 28 days qdinderstiolrgth.

Table halour shows the characEristic cylinder strength ofrarlous classes of consete recomrnended for use inreinforced and prestresed o* lete design.

Clasr C2O/2$ for orample, reier to rylinder/cub strength o,20ltUmrn2and 25 N/mnP rcspecively. '

. Consrte sfi?ilgth classes and MOE

The conditions that Jififi&lre must be able to withstan4with an adeguate fector of safety of load for which it isdesignd to ens$re tlre safety of the building occupants andsuucture iBlf against eolhpse, or,ertuming or buckling.The ult*rat limit state are divided into the followingcatgories;. ECIU lo$ o, equilibrium of dre structue.

'fR krmliaihreoreEffiitEdettrmatiorolthestn cEretrstrockrElrcmber

r GEO Failure due to excessive deformation of the $oundr ilT FatitueiailurcoftlEriructmorstruciunlmemb6rs

The strergth ot maedds upon wbicb design is based is suchstre4tft below wlich results unlikely to fall.These are call dpracteristic strengths.It is assumed ftat for a gien rnaterial, the variation ofstmsth will have a nonnal dirtribfiion as shorn in figuebelow.

. The rharactedstic strength is talten as that value, belowwhich it is unlikely tlEt more thsn 5 % of the rsutts rnillfrils. Thtls statistically,

Choaeter*tic Sragrt

It

MeM sb%grh -

1.61 (St&ndcnl*vlat*n)f^- 1.64s

CGlhtstEgBr.h*

Cl*6f*tridheyftiht srrq$r

f- illlirtil.)-Ckancie*tLed6 afir,&

t-,.,l!ilh6P1Ittort&*d:tt'qe*yf-

s?c$g?ryNC?0!7

.1925.lo-.37

.,to45-so.55m

30tl?3_

24l5{17?a?9

.35t4tr!c4g'5'glqryqtqJsc75t67

turu3.1:WWlX2-]-)

The chara.eristic strcngth of stcei reinforcement is denotesbvf""Specified strengur for high yield reinforcment given in EC2is in the range of zl{E

- 6fl) lrl/mm2.

Th most cornmonly uee in the UK is grade Sfi) and grade250 plain bar is not nolr re@Snized and no longer availableforpneral used in UKiligi yield (H) bars may be dassified as:r clas A : which is normally .ssorirt d wlth mall diameter {< 12 mml. class B : whidr b mosl roffinoillt ffid for reinbrcir baF.. cLsi c : blgh ductllitywhHr ffiy b sed in rthquake desitn.

Partial safiett factor are irnportance value applied to thestrength of rBateriab and to the astions as to tak intoaccourt tft posslble mriation o{ cofftructional tolerance.The values adopted are based on experience and simplifidcahutation and considering *e probahility of reaching eachlimit itate.Partial safEty ftctor of materials {yJ

rersiiiiiirl&.titg;eqtAEidental

r For t{re design of cross-sectioa, EC2 recommended the usedof ideali*d stress-strain ctrue as shown in figure below:

lJla.cira e:is beein irith a paEbdic tortlooiig,Iq:a.{Ir!t t,.8 2,.:Iiba! slrrch pd{lrrt lhe*aio hffise -wtfde ths stffi rem

r Th uhimate design compressive strcss are given by;a f"

=4.8-s{" =s.s6tyoy* 1.5. The cofficint 0.85 tak$ account of the difference between

bendifis strenSth and the cylinder crushing shngth af thacon0r&.

. lhe factor of 15 is the usual partial safuty factor for thestrengdr of conctete.

. Th ultimate sffain E u2 = 0,fi)35 is typical for classes ofcondete s c50/6o.

. Partial safetytactorof action,Tr

:.: ., I :rr..:r:.1io:1.1r:.r:r:1,:&,e:TdtLn1.2 &il,4: N EN IN

Concrete used mostly in rompeseion, it comprcs.rive st?es6-strain curve is o, prlmary iilportance.Typi6l stress-strain cure of sncrete ir shown in fi8urebelow:

El . * @e:r lii"nr if.G*.ilriuEllha-ss sf.. bdr*;,.::::'..:i::t:.r'r:,:it:,:.. :' .'g ile orve *1*a tncn t6 ffie to

r steel is high tenslle strength materlal.. The typical stress-rtftlin cunre for hot mlled stel are shown

in figure below:

tu:Fiw3.fo): BWI9Z-H

. For design purpose EC2 recommendsd the us of idealizedcurve shown in figure below:

Eilce@hs

tu Ftgw 3.2: LE BN 1992-1-)

Swe ftse3.3: W EN 192-lJ

The behavior of the steel is identical in tension andcompression, being linear in the elastic range up to thedesign yield sress.Design yield tensile stress can be given as;

!r-=$=owt*r^ 1.15

Where;

fvx =

. ls the selfweight of the structsr, weiEht of finishes, ceilingand services. Examples of weight of materiats as given in fC1are shorirn in table below.

Characteristic yild stressPartial sarety factor of reinforcing steel

tifhMighl @ftreNomd rei8it @ffie

5@l

3.O-m'74.4-25.Og.o * 23!3.5

-108{.t-7,LO-nn

. n.b-7a.5

10.0

tu@:Tdbll-As:BN!9qI 1I

Action is the E2 terminology for loads and imposeddeformations.The cbaracteristic actions ar the actual loads that thestructure is designed to carry.These are normally thought of as a maximum loads whichwill not he exceeded during tie lifu of structure.The characteristic actions used in design and defined in EC2are as follows;r Characteristic permanent action, Gk. Characteristic variable artion, Qk. Characteristicwind action, Wk

, For each variable actions there are four representative values:. ChaEcterktic value, lQk) - an upper value wieh an inte\ded probdhility

of Dat beiaE qceeded or d lowr vdlw with on intehded prcbabilv ofheing achievet durhE some tpecifE rctqew period

. Combination value, (PoQk, -

vdl@ inteoded to tol@ q&Nnt of drcduced Frobabilw oI the simrttoa@us wurenre ol two or morewidue adiore.

t Freqlent value, { ylQk) - w lw flch thot it should be exee ded only lor ashoft pertod of time and is Bed primotw for the s"Nicfibitity limitstdtes and olfi qmideilal limit nota

r quasi-permanent value, {PrQl) - valw moy be weded lor acoreiderEbte pertod qf timet altenativeb it may be @nsideted as dadverqge looding ovq rime. t is wd ls d lhg km atfec,s dt the SLS andolso occideDtql qnd seismic ULS.

. Cause by people, furnitur, equipment etc, Which variation inmagnitude with time is considered,

. Example of variable action as giyn in ECl ar shown in tablebelow:

rrtgBbdffid#ftjs !r 16

turMd&4d#des**WWwiq

@ajrEtuersql!ffi&*Ed**.

hl*jq,rtu

ftnB*

!.F4Sr.Fmb+@ ribl

ln order to account for variation in Loads due to.. Errors in the analysis and tlesign. Constructional inaccuracies. Possible load increases

The characteristic loads Fo {Gk Qk Wk} are multiplied by theappropriate partial safety factor for loads 1I. to give thedesign action acting on the structure,

Fo = FrxT'

Value of11 are given in EN 19lX): Annex A1

t The first function in design is the planning carried out by tharchitect to determine the anangeme[t and layout of thbuilding to meet the client's rEquirements.

r The structural engineer theil determines the best structuratsystem or forms to bring th architect's concept into being.

. Construction in different mderials and with differentarangemnts and systems may require investigation todetermine the most economical ansrer.

I Architect and ngineer should work together at thisconceptual design stage.

Remmmended Elues for P action for buildint

F: u66e w, rt&ideardeb. loliI

g: @f (K Eh- 1991-l-l: aLIliai loada oa brlldis (re lds LtiJ: :i0:)

iEl}niligrctr+Eli1t l-l-it'Se.lk ]IS E{ 1C91-l.l! (t Er. J^t,:(l}

. ome the building ,orm and surxtural arngefient harrebeen firalied the design prollem consists of th fo$on iry!. lde*lizEtion of the structura trto loadbearirg frarres and

elemenB branalyeir and design. ertim*io*ofaction*, anatFis to determine de maximum moments and shears

for design. design of sctions and rieinfortement amngpmentsior

dabs, beams, columns and foundatioff using the resultsfrorn abane

. production of arrangeme!* and detail drawingp and batschedules