1、Designation: D 7205/D 7205M 06Standard Test Method forTensile Properties of Fiber Reinforced Polymer MatrixComposite Bars1This standard is issued under the fixed designation D 7205/D 7205M; the number immediately following the designation indicates theyear of original adoption or, in the case of rev
2、ision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method determines the quasi-static longitudinaltensile strength and elongation propertie
3、s of fiber reinforcedpolymer matrix (FRP) composite bars commonly used astensile elements in reinforced, prestressed, or post-tensionedconcrete.NOTE 1Additional procedures for determining tensile properties ofpolymer matrix composites may be found in test methods D 3039/D 3039M and D 3916.1.2 Linear
4、 elements used for reinforcing Portland cementconcrete are referred to as bars, rebar, rods, or tendons,depending on the specific application. This test method isapplicable to all such reinforcements within the limitationsnoted in the method. The test articles are referred to as bars inthis test met
5、hod. In general, bars have solid cross-sections anda regular pattern of surface undulations and/or a coating ofbonded particles that promote mechanical interlock betweenthe bar and concrete. The test method is also appropriate foruse with linear segments cut from a grid. Specific details forpreparin
6、g and testing of bars and grids are provided. In somecases, anchors may be necessary to prevent grip-induceddamage to the ends of the bar or grid. Recommended details forthe anchors are provided in Annex A1.1.3 The strength values provided by this method are short-term static strengths that do not a
7、ccount for sustained static orfatigue loading. Additional material characterization may berequired, especially for bars that are to be used under highlevels of sustained or repeated loading.1.4 This standard does not purport to address all of thesafety problems, if any, associated with its use. It i
8、s theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. Within the text, thein
9、ch-pound units are shown in brackets. The values stated ineach system are not exact equivalents; therefore, each systemmust be used independently of the other. Combining valuesfrom the two systems may result in nonconformance with thestandard.2. Referenced Documents2.1 ASTM Standards:2A 615/A 615M S
10、pecification for Deformed and PlainCarbon-Steel Bars for Concrete ReinforcementD 792 Test Methods for Density and Specific Gravity (Rela-tive Density) of Plastics by DisplacementD 883 Terminology Relating to PlasticsD 3039/D 3039M Test Method for Tensile Properties ofPolymer Matrix Composite Materia
11、lsD 3171 Test Methods for Constituent Content of CompositeMaterialsD 3878 Terminology for Composite MaterialsD 3916 Test Method for Tensile Properties of PultrudedGlass-Fiber-Reinforced Plastic RodD 5229/D 5229M Test Method for Moisture AbsorptionProperties and Equilibrium Conditioning of Polymer Ma
12、-trix Composite MaterialsE4 Practices for Force Verification of Testing MachinesE6 Terminology Relating to Methods of Mechanical Test-ingE83 Practice for Verification and Classification of Exten-someter SystemE 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerable Error, th
13、e Average for aCharacteristic of a Lot or ProcessE 456 Terminology Relating to Quality and StatisticsE 1012 Practice for Verification of Test Frame and Speci-men Alignment Under Tensile and Compressive AxialForce ApplicationE 1309 Guide for Identification of Fiber-ReinforcedPolymer-Matrix Composite
14、Materials in DatabasesE 1434 Guide for Recording Mechanical Test Data of Fiber-Reinforced Composite Materials in DatabasesE 1471 Guide for Identification of Fibers, Fillers, and Core1This test method is under the jurisidiction of ASTM Committee D30 onComposite Materials and is the direct responsibil
15、ity of Subcommittee D30.05 onStructural Test Methods.Current edition approved March 15, 2006. Published April 2006.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to t
16、he standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Materials in Computerized Material Property Databases3. Terminology3.1 Terminology in D 3878 defines terms relating to high-modulus
17、 fibers and their composites. Terminology in D 883defines terms relating to plastics. Terminology in E6definesterms relating to mechanical testing. Terminology in E 456 andin Practice E 122 define terms relating to statistics and theselection of sample sizes. In the event of a conflict betweenterms,
18、 Terminology in D 3878 shall have precedence over theother terminology standards.3.2 Definitions of Terms Specific to This Standard:3.2.1 anchor, na protective device placed on each end ofa bar, between the bar and the grips of the tensile testingmachine, to prevent grip-induced damage. Usually used
19、 onbars with irregular surfaces, as opposed to flat strips wherebonded tabs are more typical.3.2.2 bar, na linear element, often with surface undula-tions or a coating of particles that promote mechanical inter-lock with concrete3.2.3 grid, na two-dimensional (planar) or three-dimensional (spatial)
20、rigid array of interconnected FRP barsthat form a contiguous lattice that can be used to reinforceconcrete. The lattice can be manufactured with integrallyconnected bars or constructed of mechanically connectedindividual bars. The grid bar elements have transverse dimen-sions typically greater than
21、3 mm 0.125 in.3.2.4 effective diameter, na geometric value representingthe diameter of a circle which has an enclosed area equal to thenominal cross-sectional area of a bar.3.2.5 nominal cross-sectional area, na measure of cross-sectional area of a bar, determined over at least one represen-tative l
22、ength, used to calculate stress.3.2.6 nominal value, na value, existing in name only,assigned to a measurable property for the purpose of conve-nient designation. Tolerances may be applied to a nominalvalue to define an acceptable range for the property.3.2.7 representative length, nthe minimum leng
23、th of a barthat contains a repeating geometric pattern that, placed end-to-end, reproduces the geometric pattern of a continuous bar(usually used in reference to bars having surface undulationsfor enhancing interlock with concrete).3.2.8 standard cross-sectional area, nthe cross-sectionalarea of a s
24、tandard numbered steel concrete reinforcing bar asgiven in ASTM A 615/A 615M, Table 1.3.2.9 surface undulation, nvariation in the area, orienta-tion, or shape of cross-section of a bar along its length,intended to enhance mechanical interlock between a bar andconcrete, made by any of a number of pro
25、cesses such as, forexample, indentation, addition of extra materials, and twisting.3.3 Symbols:A = nominal cross-sectional area of a bar.CV = sample coefficient of variation, in percent.d = effective bar diameterEchord= chord modulus of elasticity in the test direction.Ftu= ultimate tensile strength
26、.L = free length of specimen (length between an-chors).La= anchor length.Lg= extensometer gage length.n = number of specimens.P = force carried by specimen.Pmax= maximum load carried by a test coupon beforefailure.Sn1= sample standard deviation.xi= measured or derived property.x = sample mean (avera
27、ge).d = extensional displacement.e = indicated normal strain from strain transducer.s = normal stress.4. Summary of Test Method4.1 A fiber reinforced polymer (FRP) bar, preferably fittedwith anchors, is mounted in a mechanical testing machine andmonotonically loaded in tension to failure while recor
28、dingforce, longitudinal strain, and longitudinal displacement.4.2 Anchors as described in Annex A1 are recommendedbut not required. Alternative methods for attaching the speci-mens to the testing machine are acceptable, but must allow forthe full strength of the bar to be developed and for the failu
29、reof the specimens to occur away from the attachments.5. Significance and Use5.1 This test method is designed to produce longitudinaltensile strength and elongation data. From a tension test, avariety of data are acquired that are needed for designpurposes. Material-related factors that influence th
30、e tensileresponse of bars and should therefore be reported include thefollowing: constituent materials, void content, volume percentreinforcement, methods of fabrication, and fiber reinforcementarchitecture. Similarly, test factors relevant to the measuredtensile response of bars include specimen pr
31、eparation, speci-men conditioning, environment of testing, specimen alignmentand gripping, and speed of testing. Properties, in the testdirection, that may be obtained from this test method include:5.1.1 Ultimate tensile strength,5.1.2 Ultimate tensile strain,5.1.3 Tensile chord modulus of elasticit
32、y, and5.1.4 Stress-strain curve.6. Interferences6.1 The results from the procedures presented are limited tothe material and test factors listed in Section 5.6.2 GrippingThe method of gripping has been known tocause premature tensile failures in bars. Anchors, if used,should be designed in such a wa
33、y that the full tensile capacitycan be achieved without slip throughout the length of theanchor during the test.6.3 System AlignmentExcessive bending may cause pre-mature failure, as well as a highly inaccurate modulus ofelasticity determination. Every effort should be made to elimi-nate bending fro
34、m the test system. Bending may occur due tomisalignment of the bar within anchors or grips or associatedfixturing, or from the specimen itself if improperly installed inthe grips or if it is out-of-tolerance due to poor specimenD 7205/D 7205M 062preparation. See ASTM E 1012 for verification of speci
35、menalignment under tensile loading.6.4 Measurement of Cross-Sectional AreaThe nominalcross-sectional area of the bar is measured by immersing aprescribed length of the specimen in water to determine itsbuoyant weight. Bar configurations that trap air during immer-sion (aside from minor porosity) can
36、not be assessed using thismethod. This method may not be appropriate for bars that havelarge variations in cross-sectional area along the length of thebar.7. Apparatus7.1 MicrometersThe micrometer(s) shall use a suitablesize diameter ball-interface on irregular surfaces and a flatanvil interface on
37、machined edges or very-smooth tooledsurfaces. The accuracy of the instruments shall be suitable forreading to within 1 % of the intended measurement.7.2 Testing MachineThe testing machine shall be inconformance with Practice E4, and shall satisfy the followingrequirements:7.2.1 Testing Machine Heads
38、The testing machine shallhave both an essentially stationary head and a movable head.7.2.2 Drive MechanismThe testing machine drive mecha-nism shall be capable of imparting to the movable head acontrolled displacement rate with respect to the stationaryhead. The displacement rate of the movable head
39、 shall becapable of being regulated as specified in 11.3.7.2.3 Force IndicatorThe testing machine force-sensingdevice shall be capable of indicating the total force beingcarried by the specimen. This device shall be essentially freefrom inertia-lag at the specified rate of testing and shallindicate
40、the force with an accuracy over the load range(s) ofinterest of within 6 1 % of the indicated value, as specified byPractices E4. The force range(s) of interest may be fairly lowfor modulus evaluation, much higher for strength evaluation, orboth, as required.NOTE 2Obtaining precision force data over
41、 a large range of interest inthe same test, such as when both elastic modulus and ultimate force arebeing determined, place extreme requirements on the force transducer andits calibration. For some equipment a special calibration may be required.For some combinations of material and force transducer
42、, simultaneousprecision measurement of both elastic modulus and ultimate strength maynot be possible, and measurement of modulus and strength may have to beperformed in separate tests using a different force transducer range foreach test.7.2.4 GripsIf grips are used, each head of the testingmachine
43、shall carry one grip for holding the specimen so thatthe loading direction is coincident with the longitudinal axis ofthe specimen. The grips shall apply sufficient lateral pressure toprevent slippage between the grip face and the specimen oranchor. It is highly desirable to use grips that are rotat
44、ionallyself-aligning to minimize bending stresses in the specimen.The grips shall be aligned in accordance with ASTM E 1012and shall not bias failure location in the bar.7.3 AnchorsUse of a rigid pipe-shaped anchor as aninterface between the bar and the grips or loading head of thetesting machine is
45、 recommended to prevent stress concentra-tions and consequent downward biasing of measured strength.Details of recommended anchors are provided in Annex A1.7.3.1 Attachment of anchors to loading heads shall be bythreaded connectors between the anchors and loading head orby grips. Details of this att
46、achment are shown in Fig. A1.3.7.4 Strain-Indicating DeviceLongitudinal strain shall bemeasured by an appropriate strain transducer as long asattachment of this device does not cause damage to the bar (seeNote 3).NOTE 3For most bars the application of surface-bonded strain gagesis impractical due to
47、 surface undulations (for example, braided, twisted,and indented bars). Strain gages of a suitable gage length can be used ifthe surface of the bar can be smoothed with a polymer resin such as epoxyto provide a suitable bonding surface so that measurements are equivalentto those provided by an exten
48、someter meeting the requirements of section7.4.1.7.4.1 ExtensometersExtensometers shall satisfy, at aminimum, Practice E83, Class B-2 requirements for the strainrange of interest, and shall be calibrated over that strain rangein accordance with Practice E83. The extensometer shall beessentially free
49、 of inertia-lag at the specified speed of testing.The gage length of the extensometer, Lg, shall be not less thaneight times the effective bar diameter, nor less than onerepresentative length. The extensometer shall be centered onthe mid-length position of the bar, not less than eight effectivebar diameters from either anchor7.4.1.1 Temperature compensation is recommended whennot testing at Standard Laboratory Atmosphere. When appro-priate, use either (a) a traveler specimen (dummy specimen)with identical bar material and extensometer(s) or (b) anextensomet
