GB/T 14370-1993 Anchors, clamps and connectors for prestressed tendons GB/T14370-93
Some standard content:
Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
GB/T 14370—93
Anchorage, grip and coupler
for prestressing tendons
Published on May 3, 1993
Implemented on December 1, 1993
State Bureau of Technical Supervision
W Engineering Construction Standard Full-text Information System
National Standard of the People's Republic of China
Anchorage, grip and coupler
for prestressing tendons tendons
1 Subject content and scope of application
GB/T14370-93
This standard specifies the product classification, technical requirements, test methods, inspection rules, marking, packaging, transportation, storage, etc. of anchors, clamps and connectors for prestressed tendons. This standard applies to anchors, clamps and connectors used in prestressed concrete structures. When the project has special requirements for the product, special regulations must be followed.
2 Reference standards
GBJ132 Basic terms and general symbols for engineering structure design GB1804 Tolerances and fits - Limit deviations of dimensions without tolerances GB197 Tolerances and fits for ordinary threads (diameter 1~355mm) JJ11 General technical conditions for forging of construction machinery JJ13 General technical conditions for heat treatment of construction machinery JJ14 General technical conditions for processing of construction machinery JJ17 General technical conditions for packaging of construction machinery 3 Terms and symbols
3.1 Terms
3.1.1 Anchorage: In post-tensioned structures or components, a permanent fixing device is used to maintain the tension of prestressed tendons and transfer it to the concrete.
3.1.2 Grip: A temporary anchoring device used to maintain the tension of the prestressed tendons and fix them on the tensioning pedestal (or equipment) during the construction of pre-tensioned structures or components; a temporary anchoring device (also known as a tool anchor) that can transfer the tension of the jack (or other tensioning equipment) to the prestressed tendons during the construction of post-tensioned structures or components. 3.1.3 Coupler: A device used to connect prestressed tendons. 3.1.4 Prestressed steel: A general term for various steel wires, steel strands and steel bars for prestressed concrete. 3.1.5 Prestressed tendons: A single or bundled prestressed steel wire, steel strand or steel bar used to establish prestress in prestressed structures.
3.1.6 Prestressed tendon anchor assembly: A force-bearing unit assembled from prestressed tendons and anchors.
3.1.7 Prestressing tendon-gripassembly: a load-bearing unit formed by the combination of prestressing tendons and clamps. wwW.bzxz.Net
3.1.8 Prestressing tendon connector assembly: a load-bearing unit formed by the combination of prestressing tendons and connectors. Approved by the State Administration of Technical Supervision on May 3, 1993 and implemented on December 1, 1993
W.bzsoso.con Engineering Construction Standard Full Text Information System
3.1.9 Draw-in: the shrinkage value of the prestressed tendon caused by the relative displacement and local plastic deformation between the various parts of the anchor and between the anchor and the prestressed tendon during the anchoring process of the prestressed tendon. 3.1.10 Ultimate tensile force often on-anchorage assembly: the maximum tensile force reached by the anchor assembly during the static load test. 3.1.11 Ultimate tensile force often on-grip assembly: the maximum tensile force reached by the clamp assembly during the static load test. 3.1.12 Stressed length: the length of the prestressed tendon between two anchors or clamps or between an anchor and a connector during the anchor, clamp, or connector test. 3.2 Symbols
Fspu——measured ultimate tensile force of the prestressed tendon anchor assembly; Fu——the sum of the calculated ultimate tensile force of each prestressed steel in the prestressed tendon anchor assembly; Fgpu——measured ultimate tensile force of the prestressed tendon clamp assembly; Fpu—the sum of the calculated ultimate tensile force of each prestressed steel in the prestressed tendon clamp assembly; Eapu
total strain of the prestressed tendon anchor assembly when the measured ultimate tensile force is reached; A, the total cross-sectional area of each prestressed steel in the prestressed tendon anchor and clamp assembly; fpm—the residual strain of a specimen extracted from the prestressed steel =The average yield strength of the sample when the stress reaches 0.2%; fptm
-The average ultimate tensile strength of the sample extracted from the prestressed steel;-The average strain of the sample extracted from the prestressed steel when the stress reaches the yield strength;-The average ultimate strain of the sample extracted from the prestressed steel when the stress reaches the ultimate tensile strength;-The average cross-sectional area of the sample extracted from the prestressed steel; αm-The average strength ratio of the sample extracted from the prestressed steel;-The standard deviation of the ultimate strain of the sample extracted from the prestressed steel; Se
6.-The coefficient of variation of the ultimate strain of the sample extracted from the prestressed steel;-The efficiency coefficient of the prestressed tendon anchor assembly measured by the static load test; na
ns-The efficiency coefficient of the prestressed tendon clamp assembly measured by the static load test;-The efficiency coefficient of the prestressed tendon.
4 Product classification, model and marking
4.1 Product classification
According to the different anchoring methods, anchors, clamps and connectors can be divided into four types: clip type, support type, cone plug type and grip type. According to the different anchoring performances, anchors can be divided into two types: Class I and Class II.
4.2 Model and marking
The model of anchors, clamps and connectors can be represented by two Chinese pinyin letters. The first letter is the code of the prestressed system, which is selected by the research and development unit. If there is no research and development unit, it can be omitted. The second letter is the code of the anchor, clamp or connector, see Table 1. Table 1
Anchoring method codes of anchors, clamps and connectors, see Table 2. Clamp
Connector
Engineering Construction Standard Full-text Information System
Anchoring method
Clip type
Support type
Cone plug type
Grip type
The marking of anchors, clamps and connectors consists of four parts: model, prestressed steel diameter, number of prestressed steel roots and anchoring method: Anchor, clamp or
Connector code
Prestressed system code
Prestressed steel
Diameter (mm)
Number of prestressed steel
Anchoring method
For example: The head anchor for anchoring 21 5mm diameter prestressed concrete steel wires is marked as M5-21D. 5 Technical requirements
5.1 Usage requirements
5.1.1 Anchors, clamps and connectors should have reliable anchoring performance and sufficient bearing capacity to ensure that the strength of the prestressed tendons is fully utilized.
5.1.2 According to the use requirements, the anchoring performance of anchors is divided into two categories: a. Class I anchors are suitable for prestressed concrete structures subjected to dynamic and static loads; b. Class I anchors are only used in areas where the stress of prestressed tendons in bonded prestressed concrete structures does not change much. 5.2 Basic characteristics
5.2.1 The static load anchoring performance of the anchor shall be determined by the anchor efficiency coefficient measured by the static load test of the prestressed tendon anchor assembly and the total strain eapa when the measured ultimate tensile force is reached. The anchor efficiency coefficient na is calculated as follows:
The sum of the calculated ultimate tensile forces of each prestressed steel in the prestressed tendon anchor assembly Fap is calculated as follows: Fapu=fptmApm
% is used: For the type inspection of the manufacturer, it should be determined according to Appendix A of this standard; for the factory inspection of the manufacturer, when the prestressed tendons are steel wires, steel strands or heat-treated steel bars, 0.97 is taken, and when the prestressed tendons are cold-drawn I, III, IV grade steel bars, % is taken as 1.00. The static load anchoring performance of the anchor shall also meet the following requirements: Class I anchor ma>0.95, eapu≥2.0%
Class I anchor na0.90, eapu≥1.7%
5.2.2 When the prestressed tendon anchor assembly reaches the measured ultimate tensile force, all parts should not have visible cracks or damage 5.2.3 Fatigue load performance
The prestressed tendon anchor assembly of Class I anchor must meet the fatigue performance test with a cycle number of 2 million times in addition to the static load anchoring performance:
When the prestressed steel is steel wire, steel strand or heat-treated steel bar, the upper limit of the test stress is 65% of the standard value of the tensile strength of the prestressed steel, and the stress amplitude is 80MPa.
When the prestressed steel is cold-drawn Class I, Class II and Class III steel bars, the upper limit of the test stress is 80% of the standard value of the tensile strength of the prestressed steel, and the stress amplitude is 80MPa.
After the specimen is subjected to 2 million cycles of load, the area of fatigue damage of the prestressed tendon due to the influence of the anchor should not be greater than 5% of the total cross-sectional area of the specimen.
5.2.4 Cyclic load performance
Anchors used in earthquake-resistant structures should also meet the requirements of 50 cycles of cyclic load tests: When the prestressed steel is steel wire, steel strand or heat-treated steel bar, the upper limit of the test stress is 80% of the standard value of the tensile strength of the prestressed steel, and the lower limit is 40% of the standard value of the tensile strength of the prestressed steel. When the prestressed steel is cold-drawn Grade I, Grade II or Grade IV steel bar, the upper limit of the test stress is the standard value of the tensile strength of the prestressed steel, and the lower limit is 40% of the standard value of the tensile strength of the prestressed steel.
The prestressed tendons should not break after 50 cycles of loading. 5.2.5 Anchors should meet the requirements of graded tensioning, supplementary tensioning and relaxation of prestressed tendons. 5.2.6 Grouting holes should be set on the anchor or its accessories, and the grouting holes should have a cross-sectional area to ensure smooth flow of slurry. 5.2.7 The static load anchoring performance of the clamp shall be determined by the clamp efficiency coefficient n measured by the static load anchoring test of the prestressed tendon clamp assembly: Fpe
ns npPspe
The static load anchoring performance of the clamp shall meet n>0.95. **o*****0（3）
% is taken as follows: When the prestressed tendon is steel wire, steel strand or heat-treated steel bar, % is taken as 0.97; when the prestressed tendon is cold-drawn Grade I, II, IV steel bar, % is taken as 1.00.
5.2.8 When the prestressed tendon clamp assembly reaches the measured ultimate tensile force, all parts should not have visible cracks or damage; they should have good self-anchoring performance and loosening performance. Clamps that need to be knocked to loosen must ensure that they have no effect on the anchoring of the prestressed tendon and do not pose a danger to the safety of operators.
5.2.9 Connectors used for post-tensioning must meet the performance requirements of Class 1 anchors, and connectors used for pre-tensioning must meet the performance requirements of clamps.
5.3 Material requirements
The materials used in the product must meet the design requirements and have certificates of mechanical properties and chemical composition, quality assurance or acceptance test reports.
5.4 Manufacturing process requirements
5.4.1 The machining of parts shall comply with the relevant provisions of JJ14. 5.4.2 The unfilled accuracy grade of the thread shall not be lower than 7H/8g in GB197. 5.4.3 The tolerance grade of the unfilled tolerance size shall not be lower than IT14 in GB1804. 5.4.4 The forging of rough parts shall comply with the relevant provisions of JJ11. Forgings shall not have defects such as forging cracks, overburning, folding and local coarse grains.
5.4.5 The parts shall be heat treated according to the drawings and shall comply with the relevant provisions of J13. Cracks, overburning and decarburization shall not occur. The heat treatment process adopted shall ensure that the metallographic structure and surface hardness of the tested surface and the working surface of the parts are consistent. 6 Test Methods
6.1 General Provisions
6.1.1 The prestressed tendon anchor, clamp or connector assembly used for the test shall be assembled from all parts and prestressed tendons. During assembly, no material that affects the anchoring performance, such as corundum, graphite, etc. (except those specified in the design) shall be added to the anchoring parts. The prestressed tendons in the bundle shall be equal in length and parallel, and their stress-bearing length shall not be less than 3m. Note: The stress-bearing length of the test piece of a single prestressed tendon shall not be less than 0.6m. 6.1.2 The test pieces used for type inspection and new product testing of the manufacturer shall be prestressed steel of the highest strength level of the same variety and specification. Anchors, clamps or connectors used for multiple varieties of prestressed steel should be tested for each variety. 6.1.3 The uncertainty of the force measuring system used for the test shall not be greater than 2%; the uncertainty of the gauge length of the measuring tool used to measure the total strain shall not be greater than 0.2% of the standard cabinet, and the uncertainty of the indicated strain shall not be greater than 0.1% of the gauge length. The test equipment and instruments shall be calibrated at least once a year. 6.2 Static load test
6.2.1 For the prestressed system in which anchors, clamps or connectors are installed first and then the prestressed tendons are tensioned, the test machine or test bench can be used for loading directly. The loading steps are as follows: 4 levels of uniform loading according to the standard value of the tensile strength of the prestressed steel of 20%, 40%, 60%, and 80%. The loading speed should be 100MPa per minute. After reaching 80%, the load is maintained for 1h, and then gradually loaded to failure. 6.2.2 For the prestressed system that prestresses the tendons before anchoring, the construction tensioning equipment should be used to tension the prestressed steel at 20%, 40%, 60%, and 80% of the standard value of the tensile strength of the prestressed steel at 4 levels at a constant speed until 80% is reached, then anchor, hold the load for 1 hour, and then use the test equipment to gradually load until failure.
If it can be proved that anchoring the prestressed steel after tensioning has no effect on the static load performance, it can also be loaded according to the method of Article 6.2.1. 6.2.3 The observation and measurement items during the test should include: a. a. Relative displacement between each prestressed tendon and anchor, clamp or connector; b. Relative displacement between various parts of anchor, clamp or connector; c.
Measured ultimate tensile force of the specimen Fape
Total strain when reaching the measured ultimate tensile force eapese.
f. Failure location and form of the specimen.
All test results should be recorded and the anchoring efficiency coefficient n or ns of the anchor, clamp or connector should be calculated accordingly. 6.3 Fatigue test
6.3.1 When the fatigue testing machine is not capable enough, as long as the test results are representative, the number of steel bars can be appropriately reduced, or a smaller specimen can be used without changing the stress of each prestressed steel bar in the specimen, but it must not be less than 1/10 of the actual number of prestressed steel bars.6.3.2 Load to the lower limit of the test stress at a speed of 100MPa/min, and then adjust the stress amplitude to reach the specified value, and start recording the number of cycles.
6.3.3 The pulse frequency of the fatigue testing machine shall not exceed 500 times per minute. 6.4 Cyclic load test
Load to the upper limit of the test stress at a speed of about 100MPa/min, and then unload to the lower limit of the test stress for the first cycle, and then the load returns from the lower limit through the upper limit to the lower limit for one cycle, and repeat 50 cycles. 6.5 Auxiliary tests
6.5.1 For new anchors, clamps and connectors, auxiliary tests shall be carried out in accordance with 6.5.2, 6.5.3 and 6.5.4. 6.5.2 Shrinkage test of anchors and clamps
The tension force of the test is the maximum tension control stress specified in the relevant design specifications. The shrinkage can be calculated based on the difference in tension of the prestressed tendons before and after anchoring; it can also be directly measured by measuring the relative displacement of the prestressed tendons at the anchorage. There shall be no less than 3 test specimens used for the test, and the average value shall be taken. 6.5.3 Friction loss test of anchor mouth
The tension force of the test is the maximum tension control stress specified in the relevant design specifications. Measure the difference in prestress before and after the anchor. There shall be no less than 3 test specimens used for the test, and the average value shall be taken.
6.5.4 Tensioning and anchoring process test
Use prestressing tensioning equipment to tension the anchor or connector used for post-tensioning in 4 levels to tension the prestressed tendons to the maximum tensioning control stress specified in the relevant design specifications. Anchor once for each tensioning level. After tensioning, relax the stress. Through the tensioning and anchoring process test, observe:
a. The possibility of temporary anchoring due to staged tensioning or reversal of the tensioning equipment; b. The uniformity of the force on each prestressed steel in the prestressed tendon after multiple tensioning and anchoring; c. The possibility of completely relaxing the prestressed tendons when a tensioning failure occurs. 7 Inspection rules
7.1 Inspection classification
The inspection of anchors, clamps and connectors is divided into factory inspection and type inspection. Factory inspection is an inspection that the manufacturer must conduct before delivering each batch of products. 7.1.1
Type inspection should generally be carried out in one of the following situations: trial production and identification of new products or old products transferred to the factory for production; after formal production, if there are major changes in structure, materials, and processes that may affect product performance; during normal production, inspection should be carried out regularly or every 2 to 3 years after accumulating a certain amount of output; d.
When the product is resumed after a long period of suspension; when the factory inspection results are significantly different from the last type inspection; when the national quality supervision and rectification agency proposes the requirement for type inspection. Type inspection should be carried out by the quality inspection agency designated by the state. 7.2 Inspection items
The inspection items for factory inspection and type inspection should comply with the provisions of Table 3. Table 3
Factory inspection items
Class I anchors and connectors for
post-tensioning
Class 1 anchors
Clamps and connectors for
pre-tensioning
7.3 Product batching and sampling method
Static load test
Static load test
Static load test
Type inspection items
Static load test
Fatigue test
Cyclic load test
Auxiliary test
Static load test
Auxiliary test
The quantity of each batch of products refers to the quantity of the same type of products, the same batch of raw materials, and the same process produced at one time. Each batch shall not exceed 1000 sets. 10% of the samples shall be sampled for appearance inspection, and no less than 10 sets. 5% of the samples shall be sampled for hardness inspection, and no less than 5 sets shall be sampled for hardness inspection. For the clips of the multi-hole clip-type anchor, at least 5 clips shall be sampled for each set. For the static load anchoring capacity inspection, fatigue load inspection and cyclic load inspection, 3 sets of test pieces of anchors, clamps or connectors shall be sampled for each set. 7.4 Determination of inspection results
If there are no cracks on the surface and the size meets the design requirements, it shall be judged as qualified; if there is a set with cracks on the surface or exceeds the allowable deviation, W Engineering Construction Standard Full Text Information System
shall take double the number of parts for re-inspection. If there is still one set that does not meet the requirements, they shall be inspected one by one. Only qualified ones can be used. For hardness inspection, each part shall be tested at 3 points. When the hardness value meets the design requirements, it shall be judged as qualified. If there is one part that fails, double the number of parts shall be taken for re-inspection. If there is still one part that fails, they shall be inspected one by one. Only qualified ones can be used. The static load anchoring capacity test, fatigue load test and cyclic load test shall be judged as qualified if they meet the requirements of the technical requirements of Chapter 5; if one test piece fails to meet the requirements, double the number shall be taken for retesting. If one test piece still fails, the batch shall be considered as unqualified. 8 Marking, packaging, transportation, purchase and storage
8.1 Marking
Anchors, clamps and connectors shall have the manufacturer's name, product name, product model or mark, manufacturing date or production batch number. Anchor parts that are easy to confuse and difficult to distinguish (such as clips) shall have identification marks. 8.2 Packaging
Anchors, clamps and connectors shall be packed in boxes when leaving the factory and shall comply with the relevant provisions of JJ17. The packaging box must be accompanied by a product certificate, packing list and product manual.
The content of the product certificate includes:
Model and specification;
Applicable prestressed steel type, specification, strength grade; c.
Anchoring performance category;
Product batch number:
Factory date;
Quality seal;
Factory name and address.
8.3 Transportation and storage
Anchors, clamps and connectors should be kept by designated personnel. They should be well protected during storage and transportation to avoid rust, contamination, mechanical damage or loss. Temporary protection measures should not affect the effect of installation operations and the implementation of permanent anti-rust measures. W.bzsosO.coI Engineering Construction Standard Full Text Information System
Appendix A
Calculation of efficiency coefficient of prestressed tendons
(Supplement)
Before testing the prestressed anchor, clamp or connector assembly, a tensile test of a single prestressed steel must be carried out. The tensile test specimens should be drawn from the prestressed steel of the assembly, and the same batch of steel with the same diameter is a batch, and 10 to 30 specimens are randomly drawn from each batch as specimens.
During the tensile test, the following parameters should be calculated: Apm
average cross-sectional area of prestressed steel sample specimens; average yield strength of prestressed steel sample specimens at a residual strain of 0.2%; average ultimate strength of prestressed steel sample specimens; average strain of prestressed steel sample specimens when the stress reaches the yield strength; average ultimate strain of prestressed steel sample specimens; standard deviation of ultimate strain of prestressed steel sample specimens; coefficient of variation of ultimate strain of prestressed steel sample specimens. The coefficient of variation of ultimate strain of prestressed steel can be calculated by the following formula: Oept
where: to.g
-the bilateral quantile value of t distribution, with a confidence level of 0.9; j——the number of specimens,
k4—the confidence coefficient of the standard deviation. When calculating
, k and ta.s/ can be taken according to Appendix A1. The efficiency coefficient of prestressed tendons can be obtained by the following formula: =2m+(1-m)Pgm(1-1. 640,)-8m8ptm-8pym
The average yield strength ratio of prestressed steel specimens can be obtained by the following formula: 2
W. (A1)
Engineering Construction Standard Full Text Information System
Additional Notes:
This standard is proposed by the Ministry of Construction of the People's Republic of China. Continued Table A1
This standard is under the jurisdiction of the China Academy of Building Research, the technical authority for construction engineering standards of the Ministry of Construction. k4
This standard was drafted by the China Academy of Building Research, China Highway and Bridge Construction Corporation, Beijing Municipal Engineering Design Institute, Tianjin Municipal Engineering Survey and Design Institute, Ministry of Railways Scientific Research Institute, Siping Construction Machinery Factory, and Liuzhou Construction Machinery Factory. The main responsible drafters of this standard are Ding Fangru, Zhuang, Chen Zhong, Lu Jing, Zhang Qingjie, Kong Fanrui, Luo Baoheng, Qian Yongling, Zhuang Junsheng, Yang Fu, and Huang Shiyong.
This standard is entrusted to the China Academy of Building Research for interpretation. w.bzsoso：com1 Marking
Anchors, clamps and connectors shall have the manufacturer's name, product name, product model or mark, manufacturing date or production batch number. For anchor parts that are easy to confuse and difficult to distinguish (such as clips), identification marks shall be provided. 8.2 Packaging
Anchors, clamps and connectors shall be packed in boxes when leaving the factory and shall comply with the relevant provisions of JJ17. The packaging box must be accompanied by a product certificate, packing list and product manual.
The content of the product certificate includes:
Model and specification;
Applicable prestressed steel type, specification and strength grade; c.
Anchoring performance category;
Product batch number:
Factory date;
Quality seal;
Factory name and address.
8.3 Transportation and storage
Anchors, clamps and connectors shall be kept by a designated person. Storage and transportation should be well protected to avoid rust, pollution, mechanical damage or loss. Temporary protection measures should not affect the effect of installation operation and the implementation of permanent anti-rust measures. W.bzsosO.coI Engineering Construction Standard Full Text Information System
Appendix A
Calculation of efficiency coefficient of prestressed tendons
(Supplement)
Before testing the prestressed anchor, clamp or connector assembly, a tensile test of a single prestressed steel must be carried out. The tensile test specimens should be drawn from the prestressed steel of the assembly. The same batch of steel with the same diameter is a batch, and 10 to 30 specimens are randomly drawn from each batch as specimens.
During the tensile test, the following parameters should be calculated: Apm
average cross-sectional area of prestressed steel sample specimens; average yield strength of prestressed steel sample specimens at a residual strain of 0.2%; average ultimate strength of prestressed steel sample specimens; average strain of prestressed steel sample specimens when the stress reaches the yield strength; average ultimate strain of prestressed steel sample specimens; standard deviation of ultimate strain of prestressed steel sample specimens; coefficient of variation of ultimate strain of prestressed steel sample specimens. The coefficient of variation of ultimate strain of prestressed steel can be calculated by the following formula: Oept
where: to.g
-the bilateral quantile value of t distribution, with a confidence level of 0.9; j——the number of specimens,
k4—the confidence coefficient of the standard deviation. When calculating
, k and ta.s/ can be taken according to Appendix A1. The efficiency coefficient of prestressed tendons can be obtained by the following formula: =2m+(1-m)Pgm(1-1. 640,)-8m8ptm-8pym
The average yield strength ratio of prestressed steel specimens can be obtained by the following formula: 2
W. (A1)
Engineering Construction Standard Full Text Information System
Additional Notes:
This standard is proposed by the Ministry of Construction of the People's Republic of China. Continued Table A1
This standard is under the jurisdiction of the China Academy of Building Research, the technical authority for construction engineering standards of the Ministry of Construction. k4
This standard was drafted by the China Academy of Building Research, China Highway and Bridge Construction Corporation, Beijing Municipal Engineering Design Institute, Tianjin Municipal Engineering Survey and Design Institute, Ministry of Railways Scientific Research Institute, Siping Construction Machinery Factory, and Liuzhou Construction Machinery Factory. The main responsible drafters of this standard are Ding Fangru, Zhuang, Chen Zhong, Lu Jing, Zhang Qingjie, Kong Fanrui, Luo Baoheng, Qian Yongling, Zhuang Junsheng, Yang Fu, and Huang Shiyong.
This standard is entrusted to the China Academy of Building Research for interpretation. w.bzsoso：com1 Marking
Anchors, clamps and connectors shall have the manufacturer's name, product name, product model or mark, manufacturing date or production batch number. For anchor parts that are easy to confuse and difficult to distinguish (such as clips), identification marks shall be provided. 8.2 Packaging
Anchors, clamps and connectors shall be packed in boxes when leaving the factory and shall comply with the relevant provisions of JJ17. The packaging box must be accompanied by a product certificate, packing list and product manual.
The content of the product certificate includes:
Model and specification;
Applicable prestressed steel type, specification and strength grade; c.
Anchoring performance category;
Product batch number:
Factory date;
Quality seal;
Factory name and address.
8.3 Transportation and storage
Anchors, clamps and connectors shall be kept by a designated person. Storage and transportation should be well protected to avoid rust, pollution, mechanical damage or loss. Temporary protection measures should not affect the effect of installation operation and the implementation of permanent anti-rust measures. W.bzsosO.coI Engineering Construction Standard Full Text Information System
Appendix A
Calculation of efficiency coefficient of prestressed tendons
(Supplement)
Before testing the prestressed anchor, clamp or connector assembly, a tensile test of a single prestressed steel must be carried out. The tensile test specimens should be drawn from the prestressed steel of the assembly. The same batch of steel with the same diameter is a batch, and 10 to 30 specimens are randomly drawn from each batch as specimens.
During the tensile test, the following parameters should be calculated: Apm
average cross-sectional area of prestressed steel sample specimens; average yield strength of prestressed steel sample specimens at a residual strain of 0.2%; average ultimate strength of prestressed steel sample specimens; average strain of prestressed steel sample specimens when the stress reaches the yield strength; average ultimate strain of prestressed steel sample specimens; standard deviation of ultimate strain of prestressed steel sample specimens; coefficient of variation of ultimate strain of prestressed steel sample specimens. The coefficient of variation of ultimate strain of prestressed steel can be calculated by the following formula: Oept
where: to.g
-the bilateral quantile value of t distribution, with a confidence level of 0.9; j——the number of specimens,
k4—the confidence coefficient of the standard deviation. When calculating
, k and ta.s/ can be taken according to Appendix A1. The efficiency coefficient of prestressed tendons can be obtained by the following formula: =2m+(1-m)Pgm(1-1. 640,)-8m8ptm-8pym
The average yield strength ratio of prestressed steel specimens can be obtained by the following formula: 2
W. (A1)
Engineering Construction Standard Full Text Information System
Additional Notes:
This standard is proposed by the Ministry of Construction of the People's Republic of China. Continued Table A1
This standard is under the jurisdiction of the China Academy of Building Research, the technical authority for construction engineering standards of the Ministry of Construction. k4
This standard was drafted by the China Academy of Building Research, China Highway and Bridge Construction Corporation, Beijing Municipal Engineering Design Institute, Tianjin Municipal Engineering Survey and Design Institute, Ministry of Railways Scientific Research Institute, Siping Construction Machinery Factory, and Liuzhou Construction Machinery Factory. The main responsible drafters of this standard are Ding Fangru, Zhuang, Chen Zhong, Lu Jing, Zhang Qingjie, Kong Fanrui, Luo Baoheng, Qian Yongling, Zhuang Junsheng, Yang Fu, and Huang Shiyong.
This standard is entrusted to the China Academy of Building Research for interpretation. w.bzsoso：com
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