PDF Actual Sample: JGJ 107-2016 (PDF-excerpt released/modified date: 2020-03-08/2020-03-08. Translated/reviewed by: Wayne Zheng et al.)
| Standard ID | JGJ 107-2016 (JGJ107-2016) |
| Description (Translated English) | Technical specification for mechanical splicing of steel reinforcing bars |
| Sector / Industry | Building & Construction Industry Standard |
| Classification of Chinese Standard | P25 |
| Classification of International Standard | 91.080.40 |
| Word Count Estimation | 63,669 |
| Date of Issue | 2016-02-22 |
| Date of Implementation | 2016-08-01 |
| Older Standard (superseded by this standard) | JGJ 107-2010 |
| Quoted Standard | GB 50010; GB/T 1220; GB 1499.1; GB 1499.2; GB/T 3075; GB/T 8170; GB 13014; GB/T 14975; JGJ 355; JG/T 163; YB/T 4362 |
| Drafting Organization | China Academy of Building Research |
| Administrative Organization | Housing and Urban-Rural Development |
| Regulation (derived from) | Ministry of Housing and Urban - Rural Development Notice No.1049 of 2016 |
| Summary | This standard is applicable to the design, construction and acceptance of steel mechanical connections in concrete structures. |
ENGLISH: JGJ 107-2016 (Translated) JGJ 107-2016
INDUSTRY STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
UDC
P JGJ 107-2016
Registration No. J 986-2016
Technical specification for mechanical splicing of
steel reinforcing bars
钢筋机械连接技术规程
ISSUED ON: FEBRUARY 22, 2016
IMPLEMENTED ON: AUGUST 01, 2016
Issued by: Ministry of Housing and Urban-Rural Development of PRC
Table of Contents
Foreword ... 4
1 General provisions ... 8
2 Terms and symbols ... 9
2.1 Terms ... 9
2.2 Symbols ... 10
3 Performance requirements of splices ... 11
4 Splice applications ... 13
5 Initial type testing of splices ... 15
6 Machining and installing of splices on site ... 17
6.1 General requirements ... 17
6.2 Machining of splices on site ... 17
6.3 Installing of splices on site ... 18
7 Inspecting and accepting of splices on site ... 20
Appendix A -- Test methods for splice samples ... 24
Appendix B -- Test report of initial type testing of splices ... 30
Explanation of wording in this specification ... 36
List of quoted standards ... 37
Descriptions of provisions ... 38
Technical specification for mechanical splicing of
steel reinforcing bars
1 General provisions
1.0.1 In order to standardize the application of rebar mechanical connection in
reinforced concrete structural engineering, so as to be safe, applicable,
advanced in technology, economical and reasonable, to ensure quality, this
specification was formulated.
1.0.2 This specification is applicable to the design, construction and acceptance
of rebar mechanical connection in reinforced concrete structures of construction
projects.
1.0.3 The steel reinforcing bars used for mechanical connection shall comply
with the current national standards “Steel for the reinforcement of concrete -
Part 2: Hot rolled ribbed bars” GB 1499.2, “Quenching and self-tempering
ribbed bars for the reinforcement of concrete” GB 13014, “Stainless steel bars
for the reinforcement of concrete” YB/T 4362, “Steel for the reinforcement of
concrete - Part 1: Hot rolled plain bars” GB 1499.1.
1.0.4 In addition to this specification, the rebar mechanical connection shall also
comply with the relevant national standards.
2 Terms and symbols
2.1 Terms
2.1.1 Rebar mechanical splicing
A connection method for transmitting a force in one reinforcing bar to another
reinforcing bar through mechanical occlusion of a reinforcing bar with a
connecting member or other intervening material or pressure bearing effect on
a reinforcing bar’s end face.
2.1.2 Splice
In a complete set of devices of rebar mechanical connection, a shorted name
of rebar mechanical connections.
2.1.3 Connectors of mechanical splicing
It connects the various components for reinforcing steel bar, including sleeves
and other components.
2.1.4 Coupler or sleeve
A steel sleeve used to transmit the axial tensile or compressive force of a
reinforcing steel bar.
2.1.5 Rebar threaded sector
A threaded section at the end of a reinforcing steel bar in a splice.
2.1.6 Length of mechanical splice
The length of the splice’s connector plus the length of the segment of the
variable cross-section of the reinforcing steel bar at both ends of the connector
of mechanical splicing. The exposed threaded head and upset transition
segment of the threaded sector belong to variable cross-sectional segments.
2.1.7 Tensile strength of splice
The maximum tensile stress value of the splice sample during the tensile test.
2.1.8 Residual deformation of splice
After the splice sample is loaded and unloaded according to the specified
loading system, the deformation measured within the specified gauge distance.
2.1.9 Total elongation of splice sample at maximum tensile force
4 Splice applications
4.0.1 The selection of splice grades shall meet the following requirements:
1 In the concrete structure, where the strength of the steel reinforcing bar is
required to be fully exerted or where high ductility is required, it shall select
the grade II or grade I splices; when the area percentage of the steel splices
in the same splicing segment is 100%, it shall select grade I splice.
2 In the location of the concrete structure where the steel reinforcing bar has
high stress but has low requirements for the ductility, it may select the grade
III splices.
4.0.2 The thickness of the concrete protective layer of the connector of
mechanical splicing should comply with the provisions of the current national
standard “Code for design of concrete structures” GB 50010, meanwhile it shall
not be less than 0.75 times the minimum protective layer thickness of steel
reinforcing bars and 15 mm, whichever is larger. If necessary, it may take anti-
rust measures for the connector of mechanical splicing.
4.0.3 The splices of longitudinally stressed steel reinforcing bars in structural
members should be staggered from each other. The length of the connecting
segment of the rebar mechanical splicing shall be calculated as 35d. When the
steel reinforcing bars with different diameters are connected, it should be
calculated based on the steel reinforcing bar of smaller diameter. The area
percentages of the rebar mechanical splicing located in the same connection
segment shall meet the following requirements:
1 The splice should be set at the place where the stress of the structural
member's tensile steel reinforcing bar is relatively small. When the splice is
set at the high stress part, the percentage of the splice area of the grade III
splice in the same connection segment shall not be greater than 25%; the
area percentage of the grade II splices shall be not more than 50%. Except
for the conditions as listed in item 2 and item 4 in this clause, the splice area
percentage of the grade I splices may be not limited otherwise.
2 Splices should avoid the beam-end and column-end stirrup-densified areas
of the frame which has seismic fortification requirements; when it cannot be
avoided, it shall use the grade II splices and grade I splices. Meanwhile the
splice area percentage shall be not greater than 50%.
3 The percentage of splice area can be unrestricted for areas with small tensile
stress of tensioned steel reinforcing bars or longitudinally compressed steel
reinforcing bars.
4 For structural members that are directly subjected to repeated loads, the
5 Initial type testing of splices
5.0.1 Type testing shall be performed in the following cases:
1 When determining the splice’s performance grade;
2 When the sleeve’s material, specifications and splice processing technology
are changed;
3 When the type testing report is over 4 years.
5.0.2 Splice’s type testing samples shall meet the following requirements:
1 For each type, grade, specification, material, and process of rebar mechanical
splicing, the number of samples for type testing shall not be less than 12; of
which, the number of samples for tensile strength test of the base metal shall
be not less than 3; the number of samples for unidirectional tensile test shall
be not less than 3; the number of samples for high-stress repeated tension-
compression shall be not less than 3; the number of samples for large-
deformation repeated tension-compression shall be not less than 3;
2 The steel reinforcing bars of all samples shall be cut from the same steel
reinforcing bar;
3 The splice sample shall be installed in accordance with the requirements of
clause 6.3 of this specification;
4 The samples for type testing shall not use the pre-drawn samples.
5.0.3 The type testing of the splices shall be carried out in accordance with the
provisions of Appendix A of this specification. When the test results meet the
following requirements, they shall be assessed as qualified:
1 Strength testing: The actual measured value of the strength of each splice
sample shall meet the strength requirements of the corresponding splice
grade in Table 3.0.5 of this specification;
2 Deformation testing: The average value of the measured values of the total
deformation of the three samples under the residual deformation and the
maximum force shall meet the requirements of Table 3.0.7 of this
specification.
5.0.4 Type testing shall record the parameters of the connectors of mechanical
splicing and splices in detail. It should issue a testing report and assessment
conclusion according to the format of Appendix B of this specification.
5.0.5 When the splice is used for components that are directly subjected to
6 Machining and installing of splices on site
6.1 General requirements
6.1.1 On-site processing of rebar threaded sector and installation of splices
shall be performed according to the processing and installation technical
requirements of the providers for splice technology. The operators shall go to
work after passing the professional training. The staff shall be stable.
6.1.2 Processing of rebar threaded sector and installation of splices shall be
carried out only after passing the technical testing.
6.2 Machining of splices on site
6.2.1 The processing of straight threaded rebar threaded sector shall meet the
following requirements:
1 The end of the steel reinforcing bar shall be leveled by a band saw, grinding
wheel saw or a special steel reinforcing bar cutting machine with a circular
blade;
2 The upsetting head shall not have a transverse crack perpendicular to the
axis of the steel reinforcing bar;
3 The length of the rebar threaded sector shall meet the product design
requirements; the limit deviation shall be 0 ~ 2.0p;
4 The rebar threaded sector should meet the grade 6f accuracy requirements.
It shall use a special straight thread gauge for inspection. The go-gauge shall
be able to screw in smoothly and reach the required screw-in length. The
screw-in of no-go-gauge must not exceed 3p. The number of self-tests for
each specification shall not be less than 10%; the inspection pass rate shall
not be less than 95%.
6.2.2 The processing of the conical threaded rebar threaded sector shall meet
the following requirements:
1 There must be no local bending at the end of the steel reinforcing bar that
affects thread processing;
2 The length of the rebar threaded sector shall meet the product design
requirements; the rebar threaded sectors after tightening must not contact
each other; the limit deviation of the processing length of the threaded sector
shall be -0.5p ~ -1.5p;
7 Inspecting and accepting of splices on site
7.0.1 When splices are used in engineering, the relevant technical data of
splices submitted by the splice technology provider shall be reviewed and
accepted, which shall include the following:
1 The valid type testing report of splices used in the project;
2 Relevant technical documents for product design of splices, processing and
installation of splices;
3 Certificate of qualification of splice products and quality certificate of raw
materials for connectors of mechanical splicing.
7.0.2 The splice process testing shall be carried out for the steel reinforcing
bars of different production plants. When the steel reinforcing bar plant or splice
technology provider is replaced during construction, it shall make additional
process testing, which shall meet the following requirements:
1 All types and models of splices shall be subject to process testing, which
includes unidirectional tensile ultimate tensile strength and residual
deformation;
2 There shall be not less than 3 samples of each type of steel splices;
3 After measuring the residual deformation of the splice sample, the ultimate
tensile strength test can be continued; meanwhile it should carry out the test
according to the unidirectional tensile loading system in Table A.1.3 of this
specification;
4 The ultimate tensile strength of each sample and the average value of the
residual deformation of the 3 splice samples shall meet the requirements of
Table 3.0.5 and Table 3.0.7 of this specification;
5 When the process testing fails, it shall adjust the process parameters. After
passing the test, it can use the finally determined process parameters the
splices can be processed in batches according to the final confirmed process
parameters.
7.0.3 The rebar threaded sector’s processing shall be subject to self-inspection
in accordance with the requirements of clause 6.2 of this specification. When
the supervision or quality inspection department disagrees with the processing
quality of rebar threaded sector on-site, it may randomly take 3 splice samples
for the testing of the ultimate tensile strength and unidirectional tensile residual
deformation. If the ultimate tensile strength of one sample or the average value
of the residual deformation values of three samples is unsatisfactory, it shall
2 For the sleeve extruded splices, it shall take 10% splices according to the
acceptance batch. The diameter of the indentation or the length of the sleeve
after extrusion shall meet the requirements of item 3 of clause 6.3.3 of this
specification; the depth of the steel reinforcing bar inserted into the sleeve
shall meet the product design requirements. When the number of unqualified
inspections exceeds 10%, it may take 3 samples from the unqualified splices
in appearance inspection in this batch to carry out the ultimate tensile
strength test; it is evaluated in accordance with clause 7.0.7 of this
specification.
7.0.7 For each acceptance batch of splices, it shall randomly cut 3 splice
samples from the engineering structure for ultimate tensile strength test. It is
evaluated according to the splice grade required by the design. When the
ultimate tensile strength of the three splice samples meets the strength
requirements of the corresponding grades in Table 3.0.5 of this specification,
the acceptance batch shall be evaluated as qualified. When the ultimate tensile
strength of only 1 sample does not meet the requirements, it shall take another
6 samples for re-inspection. In the re-inspection, if the ultimate tensile strength
of one sample still fails to meet the requirements, the acceptance batch shall
be rated as unqualified.
7.0.8 For closed ring rebar splices, rebar cage splices, buried sleeve splices for
underground diaphragm walls, stainless steel rebar splices, rebar splices
between prefabricated structural members, the splices with fatigue
performance requirements, it may perform witnessed sampling. From the
processed and qualified finished products of rebar threaded sectors, randomly
cut rebar samples; follow the requirements of clause 6.3 of this specification,
assemble them with the mobilized sleeves as randomly taken to form 3 splice
samples, to carry out the ultimate tensile strength test. It is evaluated according
to the splice grade as required by design. The conformity assessment of the
acceptance batch shall comply with the provisions of clause 7.0.7 of this
specification.
7.0.9 For the on-site inspection of the same splice type, same model, same
grade, same specification, if the one-time qualification rate of the tensile
strength tests of the samples from 10 consecutive acceptance batches is 100%,
the number of splices in the acceptance batch can be expanded to 1000. When
the number of splices in the acceptance batch is less than 200, it may randomly
take 2 samples according to the sampling requirements same as those in
clause 7.0.7 or clause 7.0.8 of this specification, to perform the ultimate tensile
strength test; when the ultimate tensile strength of the 2 samples meet the
strength requirements of clause 3.0.5 of this specification, it shall take another
4 samples for reinspection; if there is still 1 sample fails in the ultimate tensile
strength test, this acceptance batch shall be rated as unqualified.
7.0.10 For validly certified splice products, the number of acceptance batches
3 δ2 is the deformation value represented by the distance between the
intersection points of the parallel line of S and the abscissa at an unloading
force of 0.5fyk As and a reverse loading force of -0.25fyk As after 4 repeated
loading of 2εyk L1;
4 δ3 and δ4 are the deformation value obtained in the same way as δ1 and δ2
after 5εyk L1 is repeatedly loaded 4 times.
A.1.4 The load stress rate when measuring the residual deformation of the
splice sample should be 2N/mm2·s-1, which shall not exceed 10N/mm2·s-1.
When measuring the total elongation or ultimate tensile strength of the splice
sample under the maximum force, the separation rate of the tester chuck should
be 0.05Lc per minute, wherein Lc is distance between the chucks of the tester.
The relative error of the speed should not be greater than ± 20%.
A.1.5 The numerical rounding off and judgment of the test results shall comply
with the provisions of the current national standard “Rules of rounding off for
numerical values & expression and judgement of limiting values” GB/T 8170.
A.2 On-site inspection
A.2.1 The instrument layout, measurement gauge distance and loading rate of
splice deformation test for residual deformation inspection during on-site
process inspection shall meet the requirements of clauses A.1.1 and A.1.4 of
this specification. In the field process inspection, when the residual deformation
inspection of the splice is carried out according to the loading system in clause
A.1.3 of this specification, it may use a tensile force of not more than 0.012Asfyk
as the nominal zero load.
A.2.2 The ultimate tensile strength test of spot checked splice sample shall
adopt a one-time loading system from zero to failure.
A.3 Fatigue testing
A.3.1 The splice sample used for fatigue test shall be manufactured and
installed according to the relevant technical requirements of the splice
technology supplier. The bending angle of the sample after assembly shall not
exceed 1°; the length of the tested segment of the sample should not be less
than 400 mm.
A.3.2 The fatigue performance test of splice sample should be performed by
the use of a low frequency test machine; the stress cycle frequency should be
selected from 5Hz to 15Hz. When a high frequency fatigue test machine is used
for fatigue tests, the stress amplitude or test results should be corrected. During
the test, when the temperature of the sample exceeds 40 °C, it shall take
cooling measures. When the rebar splice is used in high and low temperature
environments, the splice’s fatigue test shall be performed under the
Table of Contents
1 General -------------------------------------------------------------------------------------- 42
2 Terms and symbols ---------------------------------------------------------------------- 43
2.1 Terms ------------------------------------------------------------------------------------------ 43
2.2 Symbols -------------------------------------------------------------------------------------- 44
3 Performance requirements of splices --------------------------------------------- 45
4 Splice applications ---------------------------------------------------------------------- 49
5 Initial type testing of splices --------------------------------------------------------- 51
6 Machining and installing of splices on site ------------------------------------- 53
6.1 General requirements ------------------------------------------------------------------- 53
6.2 Machining of splices on site ---------------------------------------------------------- 53
6.3 Installing of splices on site ------------------------------------------------------------ 54
7 Inspecting and accepting of splices on site ------------------------------------ 56
Appendix A -- Test method for splice samples ----------------------------------- 60
A.1 Type testing -------------------------------------------------------------------------------- 60
A.2 On-site inspection ------------------------------------------------------------------------ 60
A.3 Fatigue inspection ----------------------------------------------------------------------- 61
1 General
1.0.1, 1.0.2 This specification makes uniform requirements for the performance
requirements of rebar mechanical splicing in concrete structures of construction
projects, application of splices, on-site processing and installation of splices,
and on-site inspection and acceptance of splices, which is used in combination
with the current national standard “Code for design of concrete structures” GB
50010, to ensure the quality and reasonable application of various mechanical
splices. In addition to construction works, general structures (including towers
such as television towers, chimneys, containers, municipal public infrastructure,
etc.) and other engineering structures such as highway and railway bridges,
dams, nuclear power plants, may refer to this specification.
After the promulgation and implementation of this specification, all kinds of
rebar mechanical splices, such as sleeve extruded splices, tapered threaded
splices, straight threaded splices, etc. shall comply with the provisions of this
specification. Reinforced sleeve grouting splices have special requirements and
shall comply with the relevant provisions of the current industry standard
“Technical specification for grout sleeve splicing of rebars” JGJ 355.
1.0.3 This clause specifies the applicable standards for steel reinforcing bars
used for rebar mechanical splicing; adds relevant provisions for hot-rolled round
steel reinforcing bars, residual heat treated steel reinforcing bars, stainless
steel reinforcing bars. China's stainless steel rebar industry standards have
been promulgated and implemented. The stainless steel rebar mechanical
splicing had been applied in Hong Kong-Zhuhai-Macao Bridge and other
projects. Based on domestic experience in applying stainless steel rebars, this
specification has formulated relevant provisions for the use of stainless steel
rebars for mechanical splicing.
2 Terms and symbols
2.1 Terms
2.1.1 ~ 2.1.5 Introduce the definition of terms such as rebar mechanical splicing,
splices, splices, connectors of mechanical splicing, sleeves, rebar threaded
sectors, etc.
According to this definition, the commonly used types of rebar mechanical
splicing are as follows:
① Sleeve extruded splice: A splice formed by tight engagement between the
steel sleeve of the connector of mechanical splicing under the plastic
deformation due to extruding force and the ribbed steel reinforcing bar.
② Taper threaded splice: A splice formed through engagement by the special
taper thread of the steel reinforcing bar end and the taper thread of the
connector of mechanical splicing.
③ Upset straight threaded splice: A splice formed through engagement by the
straight thread produced by upsetting the end of the steel reinforcing bar and
the thread of the connector of mechanical splicing.
④ Rolled straight threaded splice: A splice formed through engagement by the
straight thread as produced by rolling directly at the end of the steel reinforcing
bar or rolling after stripping the rib and the thread of the connector of mechanical
splicing.
⑤ Sleeve grouting splice: A butt splice of steel reinforcing bar which realizes
force transmission through hardening the mixture after inserting a single ribbed
steel reinforcing bar and injecting grouting mix into a metal sleeve.
⑥ Molten metal filling splice: The splice formed by the filling of molten metal
which is produced by the reaction of the high-temperature agent in between the
steel reinforcing bar and the sleeve of the connector of mechanical splicing.
The latter two types of splices rely mainly on the ribs on the surface of the steel
reinforcing bar and the mechanical occlusion of the hardened cement slurry or
molten metal, which transmits the tensile force or pressure in the steel
reinforcing bar to the connector of mechanical splicing, then to the other steel
reinforcing bar through the connector of mechanical splicing.
Some connectors of mechanical splicing are composed of a sleeve and other
components in order to meet the different functions of the splice. The connector
of mechanical splicing is a general term for multiple components including the
sleeve.
The above-mentioned different types of splices can be divided into different
3 Performance requirements of splices
3.0.1 The splice shall meet the requirements of strength and deformation
performance. Its performance is graded based on this.
3.0.2 This clauses stipulates that the sleeve material shall comply with the
relevant provisions of the current industry standard “Couplers for rebar
mechanical splicing” JG/T 163. In recent years, the raw materials for connecting
sleeves are mostly No.45 cold-drawn or cold-rolled precision seamless steel
tubes, which is commonly known as bright tubes. The internal stress of this type
of processed steel tube is very large. If it is not annealed, its elongation is very
low. There are hidden dangers in quality, meanwhile the sleeve is also easy to
crack in engineering applications. The product standard “Couplers for rebar
mechanical splicing” JG/T 163 specifies that for the use of this type of tube
materials, in addition to be “annealed”, it shall also meet the requirements that
the strength is not more than 800 MPa and the elongation at break is not less
than 14%. This specification reiterates that the product standard requires that
such tubes shall be annealed to remind users to pay attention to the quality
control of such tubes.
3.0.3 The strength and deformation of a splice under uniaxial tension are the
basic properties of the splice. The high-stress repeated tension-compression
performance reflects the ability of the splice to withstand high stress repeated
tension-compression under wind loads and small earthquakes. The large-
deformation repeated tension-compression performance reflects the load-
bearing capacity of the splice in the plastic deformation stage of the structure
under the strong earthquake.
The above three performances are the basic inspection items for splice’s type
testing. The fatigue performance is a selective test item according to the
application of the splice.
On-site process inspection requires inspection of unidirectional tensile residual
deformation and ultimate tensile strength.
3.0.4 This clause stipulates that the splice shall be divided into three grades of
I, II, III according to the ultimate tensile strength, residual deformation, total
elongation at maximum force, repeated tension-compression performance
under high-stress and large-deformation conditions.
Grade I splice: The ultimate tensile strength of the connector of mechanical
splicing is greater than or equal to 1.1 times the standard value of the tensile
strength of the connected steel reinforcing bars. The residual deformation is
small; it has high ductility and repeated tension-compression performance.
Grade II splice: The ultimate tensile strength of the connector of mechanical
splicing is not less than the standard value of the ultimate tensile strength of the
requirements of relevant standards of United States, Japan, France as well as
ISO for the splice strength, most of the highest-grade splices are required to be
not less than the standard value of the ultimate tensile strength of steel
reinforcing bars. This revision makes the above adjustments. After the
adjustments, the grade I splices shall still reach 1.1 times the standard value of
the ultimate tensile strength of steel reinforcing bar even the connector of
mechanical splicing fails. The failure of the connector of mechanical splicing
includes: the sleeve breaks under tension, the sleeve is longitudinally cracked,
the steel reinforcing bar is pulled out from the sleeve, the failure of other
components in the assembled splice.
3.0.6 After the splice is subjected to repeated high-stress repeated tension-
compression and large-deformation, it shall still meet the requirements of not
less than the ultimate tensile strength of the steel reinforcing bar, to ensure that
the steel reinforcing bar can exert its ductility.
3.0.7 Rebar mechanical splices will produce additional plastic deformation
during tension and repeated tension-compression; it will form unrecoverable
residual deformation after unloading (also known as slip in foreign countries),
which will adversely affect the crack width of concrete structures. Therefore, it
is necessary to control the residual deformation performance of the splice. This
specification stipulates that the residual deformation is used as the splice
deformation control index during unidirectional tension and repeated tension-
compression.
This specification stipulates that the unidirectional tensile residual deformation
testing of the splice shall be carried out during the process inspection at the
construction site, thereby solving the disadvantages of the disconnection
between the type testing and the quality of the splice on the site to a certain
extent, which is of great value to improve the quality of the splice; on the other
hand, if the residual deformation index is too strict and the failure rate of on-site
inspection is too high, it will obviously affect the construction progress and
acceptance of the project. Considering the above factors and referring to the
comparison test results of the 6 reinforced splice beams and whole-reinforced
beams completed by the compilation team in recent years, the unidirectional
tensile residual deformation index in Table 3.0.7 was developed. Grade I splices
allow 100% connection in the same member’s cross-section, with the strictest
limit value of u0. For the grade II and III splices, 50% splice area percentage is
used; therefore, the limit value can be appropriately relaxed.
Repeated tension-compression tests under high-stress and large-deformation
conditions are inspection requirements for the stress conditions of rebar splices
under wind loads, light earthquakes, strong earthquakes. Under wind loads or
small earthquakes, when the steel reinforcing bar has not yet yielded, it shall
be able to withstand more than 20 times of high-stress repeated tension-
compression, meanwhile meet the strength and deformation requirements.
4 Splice applications
4.0.1 The grading of splices provides conditions for structural designers to
select different grades of splices according to the importance of the structure
and the application of the splice. This specification specifies a grade I splice of
the highest quality level based on the development of domestic rebar
mechanical splicing for steel reinforcing bars and previous design habits. If
necessary, this type of splice is allowed to be used in any part of the structure
except for the frame beam end and column end stirrup reinforcement areas
where seismic fortification is required, meanwhile the splice area percentage is
not limited. This requirement creates conditions for solving special occasions
that require the implementation of 100% rebar splicing on the same cross-
section, such as the connection of underground continuous walls and horizontal
steel reinforcing splicing; the connection of vertical members and horizontal
steel reinforcing bars in slipform or lifting form construction; the connection of
steel reinforcing bars at the splice of the fabricated structure; the butt joint of
reinforcement cages; the connection of steel reinforcing bars for segmented
construction or at the joint of new and old structures, etc.
Splice grading is beneficial to reduce the sleeve’s material consumption and
splice cost. It is also conducive to determining whether to downgrade according
to the application parts and splice area percentage limits of different grades of
splices when the spot check of splice at construction site is unqualified.
The grade I and grade II splices in this specification are high-quality splices;
they can be used in the structure without restriction, but the allowable splice
area percentages are different.
4.0.2 The thickness of the concrete protective layer of the splice stipulated in
this clause has been relaxed compared with the thickness of the stressed rebar
protective layer, changing from "shall" to "should". This is because the cross-
section of the splice in the rebar mechanical splicing is larger, which is generally
10% ~ 30% or more larger than the cross-sectional area of the steel reinforcing
bar. The connector of mechanical splicing is not as sensitive to the local
corrosion as the corrosion of steel reinforcing bar. In addition, because the
thickness of the protective layer of the splice is a local issue, excessively strict
requirements will affect the spacing of all the main stressed bars and the
thickness of the protective layer, which will cause certain difficulties
economically and practically. Therefore, it can be appropriately relaxed,
meanwhile the splice may also be subjected to anti-corrosion treatment.
Considering the different requirements for the thickness of the reinforced
concrete’s protective layer under different environmental conditions, this clause
was revised from "not less than 15 mm" in the “Technical specification for
mechanical splicing of steel reinforcing bars” JGJ 107-2010 to "not less than
0.75 times the minimum protective layer thickness of steel reinforcing bar and
15 mm, whichever is larger”. If necessary, anticorrosive treatment can be
5 Initial type testing of splices
5.0.1, 5.0.2 This clause specifies when and how to perform splice type testing.
Its main function is to grade various types of splices according to their
performance. After the grade is determined by type testing, it only needs to
perform on-site inspection at construction site. When there is a serious problem
with the quality of the on-site splices, the cause of which is unclear and there
are major doubts on the conclusion of the type testing, the superior authority or
the engineering quality supervision agency may request a re-type testing.
Because type testing is more complicated and expensive, for all types of steel
splices, such as rolled straight thread splices or upset straight thread splices,
only type testing of standard splices is required.
In addition, when the same type of straight threaded splice or tapered threaded
splice is used to connect steel reinforcing bars of different strength levels (such
as 500 MPa, 400 MPa), the steel reinforcing bars of higher strength can be
selected for type test of the splice sample. Under the condition that the size,
material, internal thread and on-site threaded sector processing technology of
the sleeve are unchanged, the type testing report of the 500 MPa grade rebar
splice can be used to substitute the type testing report of the 400 MPa grade
rebar splice, otherwise it is not allowed.
The strength test of the base metal of the steel reinforcing bar is used to judge
the properties of the base metal and the designation of the steel reinforcing bar
for the splice sample.
According to the feedback from the testing organization, the testing department
does not have the ability and function to supervise and manage the installation
of splices. This clause abolished the requirement that the type testing samples
shall be delivered to the testing organization in bulk. The type test sample shall
be ensured that it has not been pre-tensioned, because pre-tensioning can
eliminate most of the residual deformation. This clause requires the testing
organization to record in detail the parameters of the connector of mechanical
splicing and splice for the type testing sample with reference to the Appendix B
of this specification, in order to check and accept the rebar splice products at
the construction site.
5.0.3 The strength requirements of splices are compulsory clauses. The
strength qualification for type testing is that each test sample shall meet the
requirements of Table 3.0.5; the measurement value of total elongation and
residual deformation of the splice sample at maximum force are relatively
scattered. Use the average of the three samples as the basis for inspection and
evaluation.
5.0.5 The fatigue performance test of splices is an optional test item. When
6 Machining and installing of splices on site
This chapter specifies the quality requirements that various types of rebar
splices shall observe during processing and installation at the construction site.
Rebar splices have their particularities as products. Except for the connector of
mechanical splicing which is produced at factory, the rebar threaded sectors
are mostly processed at the construction site. The quality control of the rebar
splices depends largely on the processing and installation of the splices at the
construction site. The clauses in this chapter are the most important quality
control requirements based on the summary of years of domestic construction
experience of rebar mechanical splices at construction sites. The formulation of
the clauses in this chapter simplified the visual inspection requirements of
splices as much as possible. This is to consider:
1 There is no definite and quantifiable internal connection between the
appearance of the splice and the splice performance so it is difficult to
formulate specific inspection indicators scientifically;
2 The appearance of the products of each production plant is inconsistent, so it
is difficult to specify uniform requirements;
3 The number of on-site splices is tens of thousands, so requiring the quality
inspection department of the civil construction organization to perform a
visual inspection of the mechanical products will cause a lot of unnecessary
disputes and misjudgments;
4 It is more appropriate to include the content of visual inspection in the
standards of each enterprise for self-control.
6.1 General requirements
6.1.1 The technology provider refers to the contracting organization for the
purchasing and processing of splices, as well as the entrusting organization for
an effective type testing report on splice performance.
6.1.2 The process inspection of splices is an important step to check the
adaptability of the mobilized steel reinforcing bars and splice processing
technology at the construction site. It shall, after the splice passes the process
inspection, use the qualified process parameters to perform batch processing
of the steel reinforcing bar at site, to avoid loss due to blind processing in large
quantity.
6.2 Machining of splices on site
6.2.1 The straight-threaded rebar splices described include upset straight-
threaded rebar splices, ribbed rolled straight-threaded rebar splices, direct
rolled straight-threaded rebar splices. The processing of the rebar threaded
7 Inspecting and accepting of splices on site
7.0.1 This clause is an important step of strengthening construction
management. It is emphasized that the splice technology provider shall submit
a full set of technical documents, which shall include:
1 Valid type testing report of splices used in the project;
2 Relevant technical documents related to product design and splice
processing and installation requirements of connectors of mechanical
splicing; for example, the enterprise standards for rebar connections, the
enterprise standards for sleeve products, etc.;
3 Certificates of quality of splicing products and quality certificates of splicing
materials, etc. These are important links in the processing, installation and
quality control of rebar splices at the construction site.
The valid type testing report of the splice means that the technical parameters
such as the splice type, model, specification, steel reinforcing bar strength and
splice performance grade in the report shall be consistent with the splice
parameters used in the project, it shall especially check the consistency of the
parameters of the screw thread and the socket thread, as well as that the
validity period of the report shall cover the construction period.
The submission of the above documents is convenient for the quality
supervision department to check and verify the processing quality of the sleeve
products and threaded sector at any time. It includes checking the types of
sleeve raw materials used in the project; for sleeves made of No.45 cold-drawn
or cold-rolled precision seamless steel tubes (commonly known as bright tubes),
it shall verify whether the steel tube’s raw materials have been annealed and
meet the requirements of current industry standard “Couplers for rebar
mechanical splicing” JG/T 163 for the strength limit and elongation at breaking
of the steel tube (according to the current national standard "Cold-drawn or
cold-rolled precision seamless steel tube" GB/T 3639, wherein the δ5 in the this
standard shall be changed to A).
7.0.2 Before the start of the splicing project of steel reinforcing bar, it shall
perform process inspection of the splice of the mobilized steel reinforcing bar
from different steel plants. The main test is to check the splice types used by
the splice technology provider (such as ribbed and rolled straight threaded
splices, upset straight threaded splices), splice form (such as standard type,
reduced diameter type, etc.), whether the processing technology parameters
are compatible with the mobilized steel reinforcing bars in this project, in order
to improve the qualification rate of sample in the actual project, reduce the
economic loss caused by problems found after the application of the project.
During the construction process, if the steel reinforcing bar’s production plant is
The conditions for the same acceptance batch are as follows: 500 splices of the
same steel reinforcing bar production plant, same strength grade, same
specification, same type, same model is treated as one acceptance batch. If it
is less than this number, it will also be considered as a batch.
7.0.6 This clause specifies the inspection items and acceptance rules after the
splices are installed. For the threaded splice, it mainly inspects the tightening
torque; for the sleeve extruded splice, it mainly checks the diameter at the
indentation or the sleeve length after extrusion as well as the length of the steel
reinforcing bar inserted into the sleeve. This clause stipulates that when the
inspection of above-mentioned external dimension of the extruded splice of the
acceptance batch fails, the inspection of ultimate tensile strength of the
acceptance batch may be performed by taking the samples from the splices
that fail the above-mentioned external dimension inspection. Under normal
circumstances, sampling from the extruded splices that failed the appearance
inspection can improve the detection rate of unqualified splices and also help
to eliminate doubts about the quality of the splices.
7.0.7, 7.0.8 According to the specific conditions in the engineering practice,
under the principle of maintaining the representativeness and randomness of
spot check of on-site splices, the contents of clause 7.0.7 of the original
specifications are basically unchanged, but the mandatory provisions are
changed to general provisions. It adds clause 7.0.8 to make special provisions
for some cases where it is not suitable to randomly intercept splice samples in
the project. Witness sampling is allowed. Under the supervision of the on-site
supervision and quality inspector, from the processed and inspection-qualified
rebar threaded sector, it randomly cut rebar sample to assemble the connector
of the mechanical splicing which is randomly taken into splice sample, to avoid
the confusion that it is not appropriate to cut the sample on site in individual
cases.
This clause further clarifies that it allows for reinspection when “only” one
sample in the acceptance batch fails to meet the requirements of tensile
strength. When there are 2 or 3 samples failing in the tensile strength, it shall
directly judge that the group is unqualified and it does not allow reinspection.
7.0.9 This clause stipulates that when the one-time qualification rate of the
tensile strength test for the samples from 10 consecutive acceptance batches
is 100%, the number of splices in the acceptance batch can be increased to
1000; considering that the number of splices in the same acceptance batch in
most small and medium-sized projects is small, in this revision, it adds the rules
for spot check and acceptance when the number of the samples in the
acceptance batch is less than 200; it is reasonable to appropriately reduce the
spot check number of splices, which will not affect the effective evaluation of
the splice quality.
Appendix A -- Test method for splice samples
A.1 Type testing
A.1.1 In this clause, the gauge length of the residual unidirectional tensile
deformation in the original specification is changed from L1 = L + 4d to L1 = L +
βd, where β is 1 ~ 6, d is the nominal diameter of the reinforcing bar, whilst the
reducer splice d may take the average value. The modification is to minimize
the variation of the measurement gauge length, reduce the measurement error,
reduce the calibration work after the measurement instrument’s gauge length
changes. When measuring the unidirectional tensile residual deformation of the
splice sample, the stress level of the steel reinforcing bar is relatively low. The
steel reinforcing bars outside the range of the length of the rebar splice are in
the elastic range, so there will be no residual deformation. The change of the
gauge length will not affect the results of the residual deformation test. When
meeting the gauge length requirements of the deformation measurement, the
splice samples of different types and specifications should use the same
measurement gauge length. The deformation measurement of the repeated
tension-compression of splice in the type testing still uses L1 = L + 4d according
to the requirements of the original specification. When the rebar splice sample
is subjected to large-deformation repeated tension-compression, the steel
reinforcing bars have entered the stage of plastic deformation. The
measurement gauge length has a significant effect on the test results. The
measurement gauge length shall remain unchanged.
A.1.2 This clause specifies the method for measuring the total elongation Asgt
of the splice sample under the maximum force in the type testing. The connector
of mechanical splicing is not included in the gauge length of the deformation
measurement, which excludes the effect of different splice lengths on the test
results, so that the total elongation index Asgt of the splice sample under the
maximum force more objectively reflects the effect of the splice on the ductility
of the steel reinforcing bar, because the structure’s ductility mainly depends on
the ductility of the steel reinforcing bar outside the splice, not the ductility of the
splice itself. The modified Asgt definition and measurement method are basically
consistent with the relevant provisions of the international standard ISO/DIS
15835.
A.1.3 Appendix Table A.1.3 specifies the loading system during the type testing
of splice sample. Figure A.1.3-1 ~ Figure A.1.3-3 further uses force-deformation
relationship to explain the loading system and the meanings of the physical
quantities in Table 3.0.5 and Table 3.0.7 of this specification.
A.2 On-site inspection
A.2.1 This clause specifies the method for measuring the unidirectional tensile
residual deformation of splice sample during on-site process inspection. The
......
(Above excerpt released/modified date: 2020-03-08 / 2020-03-08. Translated/reviewed by: Wayne Zheng et al.)
https://www.chinesestandard.net/PDF.aspx/JGJ107-2016