ASTM D7205/D7205M-06(2011)
(Test Method)Standard Test Method for Tensile Properties of Fiber Reinforced Polymer Matrix Composite Bars
Standard Test Method for Tensile Properties of Fiber Reinforced Polymer Matrix Composite Bars
SIGNIFICANCE AND USE
This test method is designed to produce longitudinal tensile strength and elongation data. From a tension test, a variety of data are acquired that are needed for design purposes. Material-related factors that influence the tensile response of bars and should therefore be reported include the following: constituent materials, void content, volume percent reinforcement, methods of fabrication, and fiber reinforcement architecture. Similarly, test factors relevant to the measured tensile response of bars include specimen preparation, specimen conditioning, environment of testing, specimen alignment and gripping, and speed of testing. Properties, in the test direction, 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 elasticity, and
5.1.4 Stress-strain curve.
SCOPE
1.1 This test method determines the quasi-static longitudinal tensile strength and elongation properties of fiber reinforced polymer matrix (FRP) composite bars commonly used as tensile elements in reinforced, prestressed, or post-tensioned concrete.Note 1
Additional procedures for determining tensile properties of polymer matrix composites may be found in test methods D 3039/D 3039M and D 3916.
1.2 Linear elements used for reinforcing Portland cement concrete are referred to as bars, rebar, rods, or tendons, depending on the specific application. This test method is applicable to all such reinforcements within the limitations noted in the method. The test articles are referred to as bars in this test method. In general, bars have solid cross-sections and a regular pattern of surface undulations and/or a coating of bonded particles that promote mechanical interlock between the bar and concrete. The test method is also appropriate for use with linear segments cut from a grid. Specific details for preparing and testing of bars and grids are provided. In some cases, anchors may be necessary to prevent grip-induced damage to the ends of the bar or grid. Recommended details for the anchors are provided in .
1.3 The strength values provided by this method are short-term static strengths that do not account for sustained static or fatigue loading. Additional material characterization may be required, especially for bars that are to be used under high levels of sustained or repeated loading.
This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.
1.5 This annex describes the recommended anchor to facilitate gripping of FRP bar specimens for various types of tests performed under tensile loading. It also specifies preparation of the specimens. Other types of anchors may be used provided it is demonstrated that (a) failure of the bar occurs outside the anchors and (b) the anchors prevent excessive slip of the bar prior to tensile failure.
1.6 This annex provides recommendations for testing bars in conditions that are other than standard laboratory conditions. These conditions may include immersion in water or other aqueous solution and/or elevated temperature or moisture conditions.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7205/D7205M − 06(Reapproved 2011)
Standard Test Method for
Tensile Properties of Fiber Reinforced Polymer Matrix
Composite Bars
This standard is issued under the fixed designation D7205/D7205M; the number immediately following the designation indicates the
year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last
reapproval. A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.4.1 Within the text, the inch-pound units are shown in
brackets.
1.1 Thistestmethoddeterminesthequasi-staticlongitudinal
1.5 This standard does not purport to address all of the
tensile strength and elongation properties of fiber reinforced
safety concerns, if any, associated with its use. It is the
polymer matrix (FRP) composite bars commonly used as
responsibility of the user of this standard to establish appro-
tensile elements in reinforced, prestressed, or post-tensioned
priate safety and health practices and determine the applica-
concrete.
bility of regulatory limitations prior to use.
NOTE 1—Additional procedures for determining tensile properties of
polymermatrixcompositesmaybefoundintestmethodsD3039/D3039M
2. Referenced Documents
and D3916.
2.1 ASTM Standards:
1.2 Linear elements used for reinforcing Portland cement
A615/A615M SpecificationforDeformedandPlainCarbon-
concrete are referred to as bars, rebar, rods, or tendons,
Steel Bars for Concrete Reinforcement
depending on the specific application. This test method is
D792 Test Methods for Density and Specific Gravity (Rela-
applicable to all such reinforcements within the limitations
tive Density) of Plastics by Displacement
noted in the method. The test articles are referred to as bars in
D883 Terminology Relating to Plastics
this test method. In general, bars have solid cross-sections and
D3039/D3039M Test Method for Tensile Properties of Poly-
a regular pattern of surface undulations and/or a coating of
mer Matrix Composite Materials
bonded particles that promote mechanical interlock between
D3171 Test Methods for Constituent Content of Composite
the bar and concrete. The test method is also appropriate for
Materials
use with linear segments cut from a grid. Specific details for
D3878 Terminology for Composite Materials
preparing and testing of bars and grids are provided. In some
D3916 Test Method for Tensile Properties of Pultruded
cases, anchors may be necessary to prevent grip-induced
Glass-Fiber-Reinforced Plastic Rod
damagetotheendsofthebarorgrid.Recommendeddetailsfor
D5229/D5229M TestMethodforMoistureAbsorptionProp-
the anchors are provided in Annex A1.
erties and Equilibrium Conditioning of Polymer Matrix
1.3 The strength values provided by this method are short-
Composite Materials
term static strengths that do not account for sustained static or
E4 Practices for Force Verification of Testing Machines
fatigue loading. Additional material characterization may be
E6 Terminology Relating to Methods of Mechanical Testing
required, especially for bars that are to be used under high
E83 Practice for Verification and Classification of Exten-
levels of sustained or repeated loading.
someter Systems
E122 Practice for Calculating Sample Size to Estimate,With
1.4 The values stated in either SI units or inch-pound units
Specified Precision, the Average for a Characteristic of a
are to be regarded separately as standard. The values stated in
Lot or Process
each system may not be exact equivalents; therefore, each
E456 Terminology Relating to Quality and Statistics
system shall be used independently of the other. Combining
E1012 Practice for Verification of Testing Frame and Speci-
values from the two systems may result in non-conformance
men Alignment Under Tensile and Compressive Axial
with the standard.
Force Application
E1309 Guide for Identification of Fiber-Reinforced
This test method is under the jurisidiction of ASTM Committee D30 on
Composite Materials and is the direct responsibility of Subcommittee D30.10 on
Composites for Civil Structures. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2011. Published December 2011. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2006. Last previous edition approved in 2006 as D7205/D7205M–06. Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D7205_D7205M-06R11. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7205/D7205M − 06 (2011)
Polymer-Matrix Composite Materials in Databases
A = nominal cross-sectional area of a bar.
E1434 Guide for Recording Mechanical Test Data of Fiber-
CV = sample coefficient of variation, in percent.
Reinforced Composite Materials in Databases
d = effective bar diameter
E1471 Guide for Identification of Fibers, Fillers, and Core E = chord modulus of elasticity in the test direction.
chord
F = ultimate tensile strength.
Materials in Computerized Material Property Databases
tu
L = free length of specimen (length between anchors).
L = anchor length.
a
3. Terminology
L = extensometer gage length.
g
3.1 Terminology in D3878 defines terms relating to high-
n = number of specimens.
modulus fibers and their composites. Terminology in D883
P = force carried by specimen.
defines terms relating to plastics. Terminology in E6 defines
P = maximum load carried by a test coupon before
max
terms relating to mechanical testing. Terminology in E456 and
failure.
in Practice E122 define terms relating to statistics and the S = sample standard deviation.
n–1
selection of sample sizes. In the event of a conflict between x = measured or derived property.
i
x¯ = sample mean (average).
terms, Terminology in D3878 shall have precedence over the
δ = extensional displacement.
other terminology standards.
ε = indicated normal strain from strain transducer.
3.2 Definitions of Terms Specific to This Standard:
σ = normal stress.
3.2.1 anchor, n—a protective device placed on each end of
a bar, between the bar and the grips of the tensile testing
4. Summary of Test Method
machine, to prevent grip-induced damage. Usually used on
4.1 A fiber reinforced polymer (FRP) bar, preferably fitted
bars with irregular surfaces, as opposed to flat strips where
with anchors, is mounted in a mechanical testing machine and
bonded tabs are more typical.
monotonically loaded in tension to failure while recording
3.2.2 bar, n—a linear element, often with surface undula-
force, longitudinal strain, and longitudinal displacement.
tions or a coating of particles that promote mechanical inter-
4.2 Anchors as described in Annex A1 are recommended
lock with concrete
but not required. Alternative methods for attaching the speci-
3.2.3 grid, n—a two-dimensional (planar) or three-
mens to the testing machine are acceptable, but must allow for
dimensional (spatial) rigid array of interconnected FRP bars
the full strength of the bar to be developed and for the failure
that form a contiguous lattice that can be used to reinforce
of the specimens to occur away from the attachments.
concrete. The lattice can be manufactured with integrally
connected bars or constructed of mechanically connected
5. Significance and Use
individual bars. The grid bar elements have transverse dimen-
5.1 This test method is designed to produce longitudinal
sions typically greater than 3 mm [0.125 in.].
tensile strength and elongation data. From a tension test, a
3.2.4 effective diameter, n—a geometric value representing
variety of data are acquired that are needed for design
the diameter of a circle which has an enclosed area equal to the
purposes. Material-related factors that influence the tensile
nominal cross-sectional area of a bar.
response of bars and should therefore be reported include the
following: constituent materials, void content, volume percent
3.2.5 nominal cross-sectional area, n—a measure of cross-
reinforcement, methods of fabrication, and fiber reinforcement
sectional area of a bar, determined over at least one represen-
architecture. Similarly, test factors relevant to the measured
tative length, used to calculate stress.
tensile response of bars include specimen preparation, speci-
3.2.6 nominal value, n—a value, existing in name only,
men conditioning, environment of testing, specimen alignment
assigned to a measurable property for the purpose of conve-
and gripping, and speed of testing. Properties, in the test
nient designation. Tolerances may be applied to a nominal
direction, that may be obtained from this test method include:
value to define an acceptable range for the property.
5.1.1 Ultimate tensile strength,
3.2.7 representative length, n—the minimum length of a bar
5.1.2 Ultimate tensile strain,
that contains a repeating geometric pattern that, placed end-to-
5.1.3 Tensile chord modulus of elasticity, and
end, reproduces the geometric pattern of a continuous bar
5.1.4 Stress-strain curve.
(usually used in reference to bars having surface undulations
for enhancing interlock with concrete). 6. Interferences
6.1 The results from the procedures presented are limited to
3.2.8 standard cross-sectional area, n—the cross-sectional
area of a standard numbered steel concrete reinforcing bar as the material and test factors listed in Section 5.
given in ASTM A615/A615M, Table 1.
6.2 Gripping—The method of gripping has been known to
3.2.9 surface undulation, n—variation in the area, cause premature tensile failures in bars. Anchors, if used,
orientation, or shape of cross-section of a bar along its length, should be designed in such a way that the full tensile capacity
intended to enhance mechanical interlock between a bar and can be achieved without slip throughout the length of the
concrete, made by any of a number of processes such as, for anchor during the test.
example, indentation, addition of extra materials, and twisting.
6.3 System Alignment—Excessive bending may cause pre-
3.3 Symbols: mature failure, as well as a highly inaccurate modulus of
D7205/D7205M − 06 (2011)
elasticity determination. Every effort should be made to elimi- 7.3 Anchors—Use of a rigid pipe-shaped anchor as an
nate bending from the test system. Bending may occur due to interface between the bar and the grips or loading head of the
misalignment of the bar within anchors or grips or associated testing machine is recommended to prevent stress concentra-
fixturing, or from the specimen itself if improperly installed in tions and consequent downward biasing of measured strength.
the grips or if it is out-of-tolerance due to poor specimen
Details of recommended anchors are provided in Annex A1.
preparation. See ASTM E1012 for verification of specimen
7.3.1 Attachment of anchors to loading heads shall be by
alignment under tensile loading.
threaded connectors between the anchors and loading head or
by grips. Details of this attachment are shown in Fig. A1.3.
6.4 Measurement of Cross-Sectional Area—The nominal
cross-sectional area of the bar is measured by immersing a
7.4 Strain-Indicating Device—Longitudinal strain shall be
prescribed length of the specimen in water to determine its
measured by an appropriate strain transducer as long as
buoyant weight. Bar configurations that trap air during immer-
attachmentofthisdevicedoesnotcausedamagetothebar(see
sion (aside from minor porosity) cannot be assessed using this
Note 3).
method.This method may not be appropriate for bars that have
large variations in cross-sectional area along the length of the NOTE 3—For most bars the application of surface-bonded strain gages
is impractical due to surface undulations (for example, braided, twisted,
bar.
and indented bars). Strain gages of a suitable gage length can be used if
7. Apparatus
the surface of the bar can be smoothed with a polymer resin such as epoxy
to provide a suitable bonding surface so that measurements are equivalent
7.1 Micrometers—The micrometer(s) shall use a suitable
to those provided by an extensometer meeting the requirements of section
size diameter ball-interface on irregular surfaces and a flat
7.4.1.
anvil interface on machined edges or very-smooth tooled
7.4.1 Extensometers—Extensometers shall satisfy, at a
surfaces. The accuracy of the instruments shall be suitable for
minimum, Practice E83, Class B-2 requirements for the strain
reading to within 1 % of the intended measurement.
range of interest, and shall be calibrated over that strain range
7.2 Testing Machine—The testing machine shall be in con-
in accordance with Practice E83. The extensometer shall be
formance with Practice E4, and shall satisfy the following
essentially free of inertia-lag at the specified speed of testing.
requirements:
The gage length of the extensometer, L , shall be not less than
g
7.2.1 Testing Machine Heads—The testing machine shall
eight times the effective bar diameter, nor less than one
have both an essentially stationary head and a movable head.
representative length. The extensometer shall be centered on
7.2.2 Drive Mechanism—The testing machine drive mecha-
the mid-length position of the bar, not less than eight effective
nism shall be capable of imparting to the movable head a
bar diameters from either anchor
controlled displacement rate with respect to the stationary
7.4.1.1 Temperature compensation is recommended when
head. The displacement rate of the movable head shall be
not testing at Standard Laboratory Atmosphere. When
capable of being regulated as specified in 11.3.
appropriate, use either (a) a traveler specimen (dummy speci-
7.2.3 Force Indicator—The testing machine force-sensing
men) with identical bar material and extensometer(s) or (b) an
device shall be capable of indicating the total force being
extensometer calibrated for temperature changes.
carried by the specimen. This device shall be essentially free
from inertia-lag at the specified rate of testing and shall
7.5 Environmental Test Chamber—Anenvironmentalcham-
indicate the force with an accuracy over the load range(s) of ber is required for conditioning and test environments other
interest of within 6 1 % of the indicated value, as specified by
than ambient laboratory conditions. These chambers shall be
Practices E4. The force range(s) of interest may be fairly low capable of maintaining the required relative temperature to
formodulusevaluation,muchhigherforstrengthevaluation,or
within 63°C [65°F] and the required relative humidity level
both, as required. to within 65 %RH. In addition, the chambers may have to be
capable of maintaining environmental conditions such as fluid
NOTE 2—Obtaining precision force
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.