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1、 E21TABLE OF CONTENTSPreface, p. E2-2Chapter 1Introduction, p. E2-21.1DefinitionsChapter 2Structural concrete: Plain, reinforced, and prestressed, p. E2-32.1Plain concrete2.2Reinforced concrete2.2.1Bending and bending stresses in reinforced concrete members2.2.2Other reinforcement applications 2.3Pr

2、estressed concrete2.3.1Bending and bending stresses in prestressed concrete members2.3.2Advantages of prestressed concrete2.3.3Pretensioned and post-tensioned concrete2.4Other prestressing applicationsChapter 3Reinforcing materials, p. E2-63.1Steel reinforcement3.1.1Deformed steel bars3.1.2Threaded

3、steel bars3.1.3Welded wire fabric3.2Fiber-reinforced polymer (FRP) bars3.2.1FRP materials3.3Fiber reinforcement3.3.1Applications3.3.2Steel fibers3.3.3Synthetic fibers3.4Materials for repair and strengthening of structural concrete members3.4.1External steel reinforcement3.4.2FRP plates, sheets, and

4、jacketsChapter 4Prestressing materials, p. E2-124.1Steel 4.1.1Seven-wire strand4.1.2Wire4.1.3Bars4.2FRP 4.2.1Strength4.2.2Applied loadsChapter 5Corrosion-resistant reinforcement, p. E2-145.1Epoxy coating5.2Galvanizing5.3Stainless steel 5.4Chemical and mineral corrosion protection systemsREINFORCEMEN

5、T FOR CONCRETEMATERIALS AND APPLICATIONSACI Education Bulletin E2-00ACI Education Bulletin E2-00.Copyright 2000, American Concrete Institute.All rights reserved including rights of reproduction and use in any form or by anymeans, including the making of copies by any photo process, or by electronic

6、ormechanical device, printed, written, or oral, or recording for sound or visual reproduc-tion or for use in any knowledge or retrieval system or device, unless permission in writ-ing is obtained from the copyright proprietors. Printed in the United States of America.The Institute is not responsible

7、 for the statements oropinions expressed in its publications. Institute publica-tions are not able to nor intended to supplant individualtraining, responsibility, or judgment of the user, or the sup-plier of the information presented.Developed by Committee E-701,Materials for Concrete ConstructionCh

8、arles K. Nmai, Chairman David M. Suchorski, SecretaryLeonard W. Bell Tarek S. Khan Kenneth B. RearRichard P. Bohan Paul D. Krauss Raymundo Rivera-VillarrealDavid A. Burg Colin L. Lobo Jere H. RoseDarrell F. Elliot Stella Lucie Marusin Paul J. TikalskyJames Ernzen Patrick L. McDowell Mark E. VincentJ

9、ames A. Farny Gerald R. Murphy Christopher H. WrightJose Pablo Garcia Anthony C. Powers* Kari L. YuersMorris Huffman Robert C. Zellers*Subcommittee Chairman.E22 ACI EDUCATION BULLETINChapter 6Storage and handling, p. E2-156.1Uncoated steel reinforcement6.2Epoxy-coated steel reinforcement6.3FRP6.4Fib

10、er reinforcementChapter 7References, p. E2-15PREFACEThis document is an introductory document on the topic ofcommonly used materials for reinforcement of concrete. Thisprimer describes the basic properties and uses of these materi-als. It is targeted at those in the concrete industry not involvedin

11、designing with or specifying these materials. Students,craftsman, inspectors, and contractors may find this a valu-able introduction to a complex topic. The document is notintended to be a state-of-the-art report, users guide, or a tech-nical discussion of past and present research findings on thesu

12、bject. More detailed information is available in ACI Com-mittee Reports listed in Chapter 7, References.CHAPTER 1INTRODUCTIONNearly everyone involved in construction knows that rein-forcement is often used in concrete. However, why it is usedand how it is used are not always well understood.This bul

13、letin provides some of the information important tounderstanding why reinforcement is placed in concrete. Mostconcrete used for construction is a combination of concreteand reinforcement that is called reinforced concrete. Steel isthe most common material used as reinforcement, but othermaterials su

14、ch as fiber-reinforced polymer (FRP) are alsoused. The reinforcement must be of the right kind, of the rightamount, and in the right place in order for the concrete struc-ture to meet its requirements for strength and serviceability.In this document, frequent references are made to stan-dards of the

15、 American Society for Testing and Materials(ASTM). These include test methods, definitions, classifica-tions, and specifications that have been formally adopted byASTM. New editions of the ASTM Book of Standards areissued annually and all references to these standards in thisbulletin refer to the mo

16、st recent edition. Other agencies havesimilar or additional standards that may be applicable.1.1DefinitionsCertain terms will be used throughout this bulletin withwhich familiarity is important. A few of the more commonand most frequently used are listed in this section. Precisetechnical definitions

17、 may be found in ACI 116R, Cementand Concrete Terminology.Bar size numberA number used to designate the barsize. Reinforcing bars are manufactured in both Interna-tional System (SIcommonly known as metricmeasuredin millimeters), and U.S. customary (in.-lb) sizes. The barnumber for metric bar sizes d

18、enotes the approximate diame-ter of the bar in millimeters. For example, a No. 13 bar isabout 13 mm in diameter (actually 12.7 mm). U.S. custom-ary bar sizes No. 3 through No. 8 have similar designations,the bar number denoting the approximate diameter ineighths of an inch (for example, a No. 5 bar

19、is about 5/8 in.in diameter).Bent bar A reinforcing bar bent to a prescribed shape,such as a straight bar with a hooked end.Compression A state in which an object is subject toloads that tend to crush or shorten it.Compression barA reinforcing bar used to resist com-pression forces.Compressive stren

20、gthA measure of the ability of theconcrete to withstand crushing loads.Elastic limitThe limit to which a material can be stressed(stretched or shortened axially) and still return to its originallength when unloaded Loads below the elastic limit result inthe material being deformed in proportion to t

21、he load. Mate-rial stretched beyond the elastic limit will continue to deformunder a constant, or even declining, load.Fibrillated fibersSynthetic fibers used to reinforceconcrete that are bundled in a mesh resembling a miniaturefish net.FRP reinforcementReinforcing bars, wires or strandmade from fi

22、ber-reinforced polymer (FRP). (Originally, the“p” in FRP stood for “plastic,” but “polymer” is now thepreferred term to avoid confusion.) Monofilament fibersDiscrete individual fibers used toreinforce concrete.Post-tensioningA method of prestressing in which thetendons are tensioned after the concre

23、te is hardened.Prestressed concreteStructural concrete in whichinternal stresses (usually compressive stresses) have beenintroduced to reduce potential tensile stresses in the con-crete resulting from loads. This introduction of internalstresses is referred to as prestressing and is usually accom-pl

24、ished through the use of tendons that are tensioned orpulled tight prior to being anchored to the concrete.PretensioningA method of prestressing in which thetendons are tensioned before concrete is hardened.RebarAn abbreviated term for reinforcing bar. Reinforced concreteStructural concrete with at

25、least acode-prescribed minimum amount of prestressed or nonpre-stressed reinforcement. Fiber-reinforced concrete is not con-sidered reinforced concrete according to this definition. Secondary reinforcementNonstructural reinforcementsuch as welded wire fabric, fibers, or bars to minimize crackwidths

26、that are caused by thermal expansion and contraction,or shrinkage. Secondary reinforcement is reinforcement usedto hold the concrete together after it cracks. Structural con-crete with only secondary reinforcement is not consideredreinforced concrete.Steel fibersCarbon or stainless steel fibers used

27、 in fi-ber-reinforced concrete meeting the requirements of ASTMA 820.Structural concreteAll concrete used for structural pur-poses including plain and reinforced concrete. TendonA wire, cable, bar, rod, or strand, or a bundle ofsuch elements, used to impart prestress to concrete. Tendonsare usually

28、made from high-strength steel, but can also bemade from such materials as FRP.E23REINFORCEMENT FOR CONCRETETensile strengthA measure of the ability of a material(for example, concrete or reinforcement) to withstand ten-sion. Tension in both the concrete and reinforcement resultswhen reinforced concr

29、ete bends under loading.TensionA state in which a material is subject to loadsthat tend to stretch or lengthen it. Yield strengthThe stress required to stretch a materialto its elastic limit. CHAPTER 2STRUCTURAL CONCRETE: PLAIN, REINFORCED, AND PRESTRESSEDThe design and construction of structural co

30、ncrete, bothplain and reinforced (including nonprestressed and pre-stressed concrete) is covered by ACI 318, Building CodeRequirements for Structural Concrete, and ACI 301, Stan-dards Specification for Structural Concrete. 2.1Plain concretePlain concrete is structural concrete without reinforcemento

31、r with less than the minimum amount required by ACI 318for reinforced concrete. It is sometimes used in slabs-on-grade, pavement, basement walls, small foundations, andcurb-and-gutter.2.2Reinforced concretePlain concrete (Fig. 2.2) has compressive strengththeability to resist crushing loads; however

32、, its tensile strengthis only about 10% of its compressive strength. Its tensilestrength is so low that it is nearly disregarded in design ofmost concrete structures. Reinforced concrete is a combina-tion of adequate reinforcement (usually steel bars withraised lugs called deformations) and concrete

33、 designed towork together to resist applied loads (Fig. 2.2). Properlyplaced reinforcement in concrete improves its compressiveand tensile strength. 2.2.1 Bending and bending stresses in reinforced concretemembersMany structural members are required to carryloads that cause bending stresses. An exam

34、ple is a simply-supported beam, in which the top of the member is subjectedto compression lengthwise while the bottom is subjected totension lengthwise (Fig. 2.2.1(a). This is referred to as beamaction and can be illustrated by supporting a board at eachend and breaking it by applying a heavy load t

35、o the center. Ifthe board is loaded at each end and supported in the middle,as in a cantilevered beam, the top of the board over the sup-port is in tension and the bottom is in compression (Fig.2.2.1(b). Unreinforced concrete structural members have lit-tle capacity for beam action because concretes

36、 low tensilestrength provides little resistance to the tensile stress in thetension side of the member. This is one of the most importantfunctions of reinforcement in concrete membersto resistthe tension in these members due to beam action (Fig.2.2.1(c). Steel is remarkably well- suited for concrete

37、 rein-forcement because it has high tensile strength, and thereforerelatively small amounts are required. Also, concrete bonds tosteel, and both expand and contract to about the same degreewith temperature changes. The good bond between concreteFig. 2.2Examples of plain and reinforced concrete: plai

38、ncurb and gutter (left) and reinforced concrete T-beam(right).Fig. 2.2.1(a)A simple beam loaded in the middle and sup-ported at the ends will tend to deflect or bend down in themiddle, causing tensile stress in the bottom of the beam andtending to pull it apart. That is, the bottom of the beam is in

39、tension. Reinforcing steel near the bottom of the beam willresist this tension and hold it together.Fig. 2.2.1(b)If the beam is supported in the middle andthe ends are loaded (as in a cantilever beam, such as a bal-cony), the top of the beam over the support is in tension andwill pull apart or crack

40、 if there is no reinforcing steel nearthe top of the beam.Fig. 2.2.1(c)Properly placed reinforcement in this canti-lever beam will resist tension and control cracking.Fig. 2.2.1(d)Incorrectly placed or missing reinforcementis not effective in resisting tension and will allow uncon-trolled cracking i

41、n the beam.E24 ACI EDUCATION BULLETINand steel allows an effective transfer of stress or load betweenthe steel and concrete so both materials act together in resist-ing beam action. For these reasons, steel is the most commonmaterial used to reinforce concrete. However, other materialssuch as FRP ar

42、e also used for reinforcement.Many structural members must perform like a beam to ful-fill their function in the structure. Among such concretestructural members are beams, girders, joists, structuralslabs of all kinds, some columns, walls that must resist lat-eral loads, and more complex members su

43、ch as foldedplates, arches, barrels, and domes. In addition to uninten-tional omission of part or all of the reinforcement, improperplacement of the reinforcement designed to resist tension isone of the most common causes of structural concrete fail-ures (Fig. 2.2.1(d). If the tensile steel is not p

44、roperly placedin the tension zone of a structural member, it will not beeffective in resisting tension, and failure may occur.2.2.2 Other reinforcement applicationsIn addition toits use to resist tension in structural members, reinforce-ment is used in concrete construction for other reasons,such as

45、: To resist a portion of the compression force in a mem-ber. The compressive strength of steel reinforcement isabout 20 times greater than that of normal-strengthconcrete. In a column, steel is sometimes used toreduce the size of the column or to increase the col-umns carrying capacity (Fig. 2.2.2(a

46、). Compressionsteel is sometimes used in beams for the same reasons.Fig. 2.2.2(a)Reinforcement in a concrete column (cour-tesy of HDR Engineering, Inc.).Fig. 2.2.2(b)Stirrups to resist shear in a concrete box girder bridge (courtesy HDR Engineering, Inc.).E25REINFORCEMENT FOR CONCRETE To resist diag

47、onal tension or shear in beams, walls, andcolumns. Reinforcement used to resist shear in beamsis commonly in the form of stirrups (Fig 2.2.2(b), butmay also consist of longitudinal reinforcement bent upat an angle near the ends of the beam, or welded wirefabric. In columns, shear reinforcement is ty

48、pically inthe form of ties, hoops, or spirals. To resist bursting stresses resulting from high compres-sive loads in columns or similar members, in whichspiral steel reinforcement, hoops (Fig. 2.2.2(c), or tiesare used. To resist internal pressures in round structures such ascircular tanks, pipes, a

49、nd bins. To minimize cracking, or more precisely, to promotenumerous small cracks in place of fewer large cracks,in concrete members and structures. To limit widths and control spacing of cracks due tostresses induced by temperature changes and shrinkage(shortening of the concrete due to drying over time) inslabs and pavement.2.3Prestressed concrete Prestressed concrete is structural concrete in which internalstresses have been introduced to reduce potential tensilestresses in the conc