Reinforced Concrete - KFUPM

1 Inthepast, , , ,reinforcedconcreteismorecommonlyusedinc onstructingbuildings,bridges, )Al)Whyconcretealoneisnotabletosupportlo adandformastructure?Becauseconcreteiswea kin tensionanditwillcracksoitneedsanotherpar tnertocarrythetensionforcewhichitselfcan ' , ) Whyweneedsteelinreinforcedconcrete?A2) Weneeditso ) Howonewouldquantifystrengthofmaterialint ensionorcompression?A3) Prepareaspecimenorreasonabledimensionsan dapplytensionorcompressionandincreasethe forceuntilitfails, =force (Norlb)A=Area (m2orin2)f=stress (Paorpsi)Q4) Whyconcretestructurewoulddeteriorate?A4) Concretestructureswoulddeterioratefortwo maincauses:1) Externallybytheeffectofharshenvironmentw herehighhumidity,temperatureandsalinityi ntheairwouldpromotecorrosionofreinforcem entespeciallyifconcreteispoorandcan' ) notusingsweetwater- usingpollutedsandoraggregate- employingpoorqualityofcementAI-Gadhib/CE 315/CE323Q5)A5)Giventhebendingmomentdiag ramfor aparticularsegmentofstructure,showproper locationofsteelalongandacrossthedepthoft hebeam.

2 (Notethatpositivemovementmeanstensionint hebottomandcompressionmeanstensionontopa ndviceversa.).erialsusedforbuildingsarew ood,steel,andcedconcreteincluding1condui tsprincipallywithdesignandinvestigations (analysis)ofreinforcedconcretememberssub jectedto:axialforce, Nbendingmoment, Mshearforce, Vtorsion, )The )Manystructuresarebuiltofreinforbridgesr etainingwallviaductstunnelsbuildingstank s3)ReinforcedconcreteisdealingAI-Gadhib/ CE315/CE323 CONCRETEP lainconcrete=cement+aggregate+water+admi xturesStrengthofconcretedependson twomajorfactors:oneistheproportionofingr edientsandtheotheristheconditionoftemper atureandmoistureunderwhichitisplacedandc ured.(1)Cement:Cementisamaterial,whichha sadhesiveandcohesiveproperty,andcomposed ofsilicates,aluminate, "hydration"andthecementitselfiscalled"hy drauliccement".

3 Thecementusedinnormalconcreteiscalled"Po rtlandCement" (concretewithcontactwithsoil)IIIH ighearlystrengthfor theremovalofformworksoonIVLowheatofhydra tionformassiveconcreteconstructionVSever esulfateresistance(2)Aggregates:Thereare twotypesofaggregate;oneisfineaggregate(s and) sieve[ or(5mm)].Coarseaggregatethosewhicharelar gerthan6/16in(5mm).Aggregateshouldbeclea n,hard,andwellgraded(containdifferentsiz es).Thequantityofaggregateisveryimportan tsincetheymakeup60-75% :1)lightweightconcrete (70-115pcf)2)normalconcrete (145pcf)3)heavyweightconcrete (250pcf)Normalconcreteismadeusingsandand stonesbutlightweightconcretecanbemadeusi ngindustrialby-productssuchasexpandedsla gor [145pcf(lb/ft)or2320kg/m3]whereaslightwe ightconcreteconformingtoASTMC330has aunitweight[70-115pcfor1120-1840kg/m3].

4 :Thoseareusedforconcreteexposedtofreeze- thawcycles. Billionsoftinyairbubblesof1mmor smallerin :Throughtheuseoftheseagents, (by-productsoftheburningofcoal) , :Theyaretoslowdownthesettingtimeespecial lyforlargemassesofconcretewhereconcreten eedtostayinplasticstateforlongtimeso asnottoformwhatiscalled"coldjoint"wheret wopatchesofconcretemayarriveat "calciumchloride".AI-Gadhib/CE315/CE323 CompressiveStrengthThestrengthofconcrete iscontrolledbytheproportioningofcement,c oarseandfineaggregates,water, (12"inheightand6"indiameter) , ' 'ofcylinder= 83%(f,'of cubeof200)= 80%(f,'ofcubeof150)Thesinglemostimportan tindicatorofstrengthistheratioofwateruse dcomparedtocementbyweight[itiscalled(wat er-cementratio)].Thehigherthew/cratiothe lowerthestrength, :4-0 ,0006,0005,0004,000E0U3,000AI-Gadhib/CE3 15/CE3234 5 6 7 8 Water-cementratio,gallonsper bagt- i ,by to2%trappedairfornon-air-entrainedconcre te,andNoMoreThan5to6%AirforAir-Entrained Concrete ( , ).

5 AAgoodindicatorofwatercontentofthemix(or workability)isobtainedbyhavinga"standard slumptest".Mostconcretemixeshaveslumpsof 2 ( )Strain, (mm/mm)Oneimportantpointisthatthelowerth estrength,thegreatertheductility(ordefor mability)..Themaximumstressisreachedatas trainrange( 5). * Ithasbeenfoundfromexperimentsthatmodulus ofelasticity(theinitialslopeofthestress- straincurve)isafunctionofconcretestrengt handitsunitweightaccordingtothefollowing :E,~=33( fC'whichforconcreteofw=145p4givesE,= 57000fc'or E~=4700f~'or Ec=15000f~' :isthepropertyofconcreteby whichitcontinuetodeformwithtimeata constantload. , Standardcreepcoefficientvariationwithdur ationofloading( ,40%relativehumidity,moistcured,andloadi ngageof7days). !CYCLNAI-Gadhib/CE315/CE323Es"= (Esn) ( )'I I i n I I I I100200300400500600 Timeaftermoistcuring, Standardshrinkagestrainvariationwithtime aftermoistcuring( ,40% ,after7daysmoistcured).)

6 Esh= (Esn) Changeinstrainofaloadedanddryingspecimen ;toisthetimeofapplicationof ,weldedwirefabric,or wires. , Deformedreinforcingbars.(CourtesyofConcr eteReinforcingSteelInstitute.)WN(a)Typic alreinforcingbarAccordingtoASTM(American SteelTestingMaterials)barsaredenotedbynu mbersand--- ) :2) ,theyare:3) #13.#3hasdiameterof3/8in#7hasdiameterof7 /8in#8hasdiameterof8/8=1in#9-area=1in2#1 0-area=11/8in2-#11-area=1'/4in24) #14and# 18 areequaltosquareofsize1% StandardReinforcingBarDimensionsandWeigh ts(BarsinInch-PoundUnitsAccordingtoASTMA 615[ ,A616[ ,A617[ , )AI-Gadhib/CE315/CE323 BARNUMBERNOMINALDIAMETER(in.)(mm)DIMENSI ONSAREA(sqin.)(cm')WEIGHT(lb/ft)(kg/m) ,forexample:Steelgrade40hasayieldstress= 40ksiSteelgrade60hasayieldstress= as#3and#4whichareusedas (WWF) isaweldedwirefabricmeshthathas 6"spacinginonedirectionand8"spacinginthe , '' '' -- -'.]]]

7 ~..^ .. ~~~e-/~.--/ou'----+*e*------'~~~-Mod---A 44~/~~c-4"a---is 74------ko,,,~An-,n4---4!~O0-U/0400)sz~~ " ,W ---54k~ro-i~%V4U= + (1AD+ + )U= + ( + + ( ) + ( )EU= + + + + + + ( + + )U=1 .4(D+T) , , ' , ` :flexure,compression,shear, (a)isometricFLATPLATE(b)sectionFLATSLABW ITHSHEARHEADSFLATSLABWITHBEAMS(a)isometr icT_HFunctionalityGoodforshortspansandli ghtloadingsuchasapartmentsand (in) (ft)SpanSlabthickness(in)Totalthicknesso f (ft) ( (~ SpanSlabTotal ~ (ft)ThicknesThicknesss25312ca,i5emctrlcc b>section3031535419 Twowaysoftransferringshearto40529columnV ONEWAYSLABThe \temperatureandshrinkageisplaceinperpend iculardirection.(a) (a) systemwhereasforresidentialspaceswithsho rtspanandlightload, isveryessentialthatthedesignershouldbeaw areofthecoordinationofthe- structuralsystem- circulationsystem- mechanicalsystem.))