ASTM D7914/D7914M-14

Standard Test Method for Strength of Fiber Reinforced Polymer (FRP) Bent Bars in Bend Locations

SIGNIFICANCE AND USE
5.1 This test method is intended to determine the bend strength developed at a standard twelve bar diameters of embedment and the strength reduction factors of FRP bent bars that are typically used as anchorages in concrete. From this 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, factors relevant to the measured tensile response of bars include specimen preparation, specimen conditioning, environment of testing, specimen alignment, and speed of testing. Properties, in the test direction, that may be obtained from this test method include:  
5.1.1 Ultimate bend strength of the FRP bent bar and  
5.1.2 Percentage of the guaranteed tensile strength of the straight portion of the bar that is retained in the bend location.  
5.2 The results may be used for material specifications, research and development, and structural design and analysis.  
Note 1: Two FRP bends are tested simultaneously in this test method, but in some cases only one bend may rupture. While resulting in a valid failure, notice should be taken that only one bend has been effectively measured and that the final compiled test results using this method could differ from those resulting from single FRP bend testing.
SCOPE
1.1 This test method determines the quasi-static ultimate strength of fiber reinforced polymer (FRP) composite bent bars commonly used as anchorages for stirrups in reinforced, prestressed, or post-tensioned concrete structures. This test method only applies to bars with a solid cross section.  
1.2 FRP bent bars are often used in reinforced concrete applications to shorten the development length of the bar or to act as a tie or a stirrup to resist shear forces. Bent bars can be produced with varying angles of bend in order to fit their intended purpose.  
1.3 For this test method, the FRP bars are bent at a 90 degree angle. In general, bars have a regular pattern of surface undulations, a coating of bonded particles, or both, that promote mechanical interlock between the bar and concrete.  
1.4 The strength values provided by this method are short-term, quasi-static tensile strengths that do not account for sustained static or cyclic loading. If bars are to be used under high levels of sustained or repeated loading, additional material characterization may be required.  
1.5 The characteristic values obtained from this test method are intended to represent the quasi-static ultimate strength of FRP bent bars with a tail length of twelve bar diameters.  
1.6 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
1.6.1 Within the text, the inch-pound units are shown in brackets.  
1.7 This standard does not purport to address all of the safety concerns, 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.

General Information

• Status: Historical
• Publication Date: 31-Jul-2014
• ICS: 83.120 - Reinforced plastics
• ICS: 91.080.40 - Concrete structures
• Technical Committee: D30 - Composite Materials
• Drafting Committee: D30.10 - Composites for Civil Structures

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: D7914/D7914M − 14
Standard Test Method for
Strength of Fiber Reinforced Polymer (FRP) Bent Bars in
1
Bend Locations
This standard is issued under the fixed designation D7914/D7914M; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method determines the quasi-static ultimate
strengthoffiberreinforcedpolymer(FRP)compositebentbars
2. Referenced Documents
commonly used as anchorages for stirrups in reinforced,
2
2.1 ASTM Standards:
prestressed, or post-tensioned concrete structures. This test
A615/A615MSpecificationforDeformedandPlainCarbon-
method only applies to bars with a solid cross section.
Steel Bars for Concrete Reinforcement
1.2 FRP bent bars are often used in reinforced concrete
C39/C39MTest Method for Compressive Strength of Cylin-
applications to shorten the development length of the bar or to
drical Concrete Specimens
act as a tie or a stirrup to resist shear forces. Bent bars can be
C143/C143MTest Method for Slump of Hydraulic-Cement
produced with varying angles of bend in order to fit their
Concrete
intended purpose.
C192/C192MPracticeforMakingandCuringConcreteTest
1.3 For this test method, the FRP bars are bent at a 90 Specimens in the Laboratory
degree angle. In general, bars have a regular pattern of surface D792Test Methods for Density and Specific Gravity (Rela-
undulations, a coating of bonded particles, or both, that tive Density) of Plastics by Displacement
promote mechanical interlock between the bar and concrete. D883Terminology Relating to Plastics
D3171Test Methods for Constituent Content of Composite
1.4 The strength values provided by this method are short-
Materials
term, quasi-static tensile strengths that do not account for
D3878Terminology for Composite Materials
sustained static or cyclic loading. If bars are to be used under
D5229/D5229MTestMethodforMoistureAbsorptionProp-
highlevelsofsustainedorrepeatedloading,additionalmaterial
erties and Equilibrium Conditioning of Polymer Matrix
characterization may be required.
Composite Materials
1.5 The characteristic values obtained from this test method
D7205/D7205MTest Method forTensile Properties of Fiber
are intended to represent the quasi-static ultimate strength of
Reinforced Polymer Matrix Composite Bars
FRP bent bars with a tail length of twelve bar diameters.
E4Practices for Force Verification of Testing Machines
1.6 The values stated in either SI units or inch-pound units E6Terminology Relating to Methods of Mechanical Testing
E122PracticeforCalculatingSampleSizetoEstimate,With
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each Specified Precision, the Average for a Characteristic of a
Lot or Process
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance E456Terminology Relating to Quality and Statistics
with the standard.
3. Terminology
1.6.1 Within the text, the inch-pound units are shown in
brackets. 3.1 Terminology in D3878 defines terms relating to high-
modulus fibers and their composites. Terminology in D883
1.7 This standard does not purport to address all of the
defines terms relating to plastics. Terminology in E6 defines
safety concerns, if any, associated with its use. It is the
terms relating to mechanical testing. Terminology in E456 and
responsibility of the user of this standard to establish appro-
in Practice E122 define terms relating to statistics and the
selection of sample sizes. In the event of a conflict between
1
This test method is under the jurisdiction of ASTM Committee D30 on
2
Composite Materials and is the direct responsibility of Subcommittee D30.10 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Composites for Civil Structures. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved Aug. 1, 2014. Published December 2014. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7914_D7914M-14. the ASTM website.
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D7914/D7914M − 14
terms, Terminology in D3878 shall have precedence over the 3.3.10 r—inside radius of the bent portion of an FRP bent
t
other terminology standards. bar, mm [in.]
3.3.11 S —sample standard deviation
3.2 Definitions:
n-1
3.2.1
...