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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$retI Elt1992 Eurocode2:
DgBnofconsetestrucnrtes
. Eurocode 2 (ECll applies to the deeign of buiHings and
ctuilnginedng works in plain, reinfurced ald ptEtrcssdconciete. EC2
cornes in several parts as follolt|r:
ENlggzPartl-2 &iBafdiiEtus--Sbstud,lt6{*xibnEN imz H 2 C@cdc
bddgE -d!S!i!d #amng ilbseru tggZ Part a Liqut rAarrim and
ontaillmrt 8lrudre
r fhe purpose ol design is to aehiare acceptable
probabilitiesthat . structure will not h@{rre IEEi fur it iAtended
use.That ls, that it will rd readr 5 limit 3tate.
t At an? way in which a stfirctut may ce-as !o b fit for U3will
constitute a lirnit stah a*d tie design aim is to avoidany such
ccndition being rcaded during the expected liia ofthe strueture
. Thre arc trvo prlncipal types of limit state:r lrltimate limit
state. SeMceability limit state
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t siE r sittlations of limit state
bl\*"n'*.nd.m$'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$g?ryNC?0!7
.1925.lo-.37
.,to45-so.55m
30tl?3_
24l5{17?a?9
.35t4tr!c4g'5'glqryqtqJsc75t67
turu3.1:WWlX2-]-)
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The chara.eristic strcngth of stcei reinforcement is
denotesbvf""Specified strengur for high yield reinforcment given in
EC2is in the range of zl{E
- 6fl) lrl/mm2.
Th most cornmonly uee in the UK is grade Sfi) and grade250 plain
bar is not nolr re@Snized and no longer availableforpneral used in
UKiligi yield (H) bars may be dassified as:r clas A : which is
normally .ssorirt d wlth mall diameter {< 12 mml. class B :
whidr b mosl roffinoillt ffid for reinbrcir baF.. cLsi c : blgh
ductllitywhHr ffiy b sed in rthquake desitn.
Partial safiett factor are irnportance value applied to
thestrength of rBateriab and to the astions as to tak intoaccourt
tft posslble mriation o{ cofftructional tolerance.The values
adopted are based on experience and simplifidcahutation and
considering *e probahility of reaching eachlimit itate.Partial
safEty ftctor of materials {yJ
rersiiiiiirl&.titg;eqtAEidental
r For t{re design of cross-sectioa, EC2 recommended the usedof
ideali*d stress-strain ctrue as shown in figure below:
lJla.cira e:is beein irith a paEbdic tortlooiig,Iq:a.{Ir!t t,.8
2,.:Iiba! slrrch pd{lrrt lhe*aio hffise -wtfde ths stffi rem
r Th uhimate design compressive strcss are given by;a f"
=4.8-s{" =s.s6tyoy* 1.5. The cofficint 0.85 tak$ 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
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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}
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. 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