Engineering Construction Standard Full-text Information System
Construction Industry Standard of the People's Republic of China JG300693
Steel strand and steelwire unbonded tendonsConstruction Standard
1993-08-31Promulgated
Ministry of Construction of the People's Republic of China
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1993-12-01Implementation
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Construction Industry Standard of the People's Republic of China Steel strand and steel wire unbonded tendonsSubject Content and Scope of Application
JG3006—93
This standard specifies the product classification, technical requirements, test methods, inspection rules, packaging, marking, storage and transportation of steel wire and steel wire unbonded tendons. Unbonded prestressed tendons are made of steel strands or carbon steel wire bundles with a special anti-corrosion grease (in accordance with "Special Anti-corrosion Grease for Unbonded Prestressed Reinforcements" JG3007) as a coating layer and polyethylene plastic as a sheath. This standard applies to unbonded prestressed tendons in post-tensioned prestressed concrete main structural components used under normal conditions. 2 Reference standards
Steel wire for prestressed concrete
Steel strand for prestressed concrete
General provisions for acceptance, packaging, marking and quality certification of steel wire 2103
Special anti-corrosion grease for unbonded prestressed tendons GB228Metallic tensile test methods
GB1845Nomenclature of polyethylene and ethylene copolymer materials 3
Classification, code and marking
Classification of unbonded prestressed tendons by type and diameter of steel bar Unbonded Prestressed steel strand: 1×7-012.0, 1×7-015.0 Unbonded prestressed carbon steel wire bundle: 705
3.2 Code and mark
The mark of unbonded prestressed tendons consists of three parts: the code of the product name, technical characteristics (including the type, specification and tensile strength standard value of prestressed steel) and the standard number: The Ministry of Construction of the People's Republic of China approved the engineering construction standard full text information system on 1993-08-31
199 3—12—01 implementation
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JG3006
Standard value of tensile strength (N/mm2)
Specification of prestressed steel (mm)
Type of prestressed steel
Stranded wire
W steel wire
Unbonded prestressed tendons
bZxz.netMarking example: The standard value of tensile strength is 1470N/mm2, 1×7-?15 .0mm steel strand unbonded prestressed tendons are marked as UTS--15-1470-JG3006; the standard value of tensile strength is 1570N/mm2, and the standard value of 7?5mm steel strand unbonded prestressed tendons are marked as UTW-7@5-1570-JG30064 Technical requirements
4.1 Prestressed high-strength steel
The steel wire or steel grain wire used to make unbonded prestressed tendons shall comply with GB5223 and GB regulations, and shall be accompanied by a quality assurance certificate.
4.2 Anti-corrosion lubricating coating
5224 regulations
The coating layer of unbonded prestressed tendons shall have good chemical stability, no invasive effect on surrounding materials, impermeable, non-hygroscopic, strong corrosion resistance; good lubrication performance, low friction resistance; no melting at high temperature, no brittleness at low temperature, and certain toughness within the specified temperature range. The coating layer shall comply with the requirements of JG3007. 4.3 Sheath material
The sheath material of unbonded prestressed tendons should preferably be high-density polyethylene. When there is reliable practical experience, polypropylene can be used. Polyvinyl chloride should not be used. The sheath material should have sufficient toughness, wear resistance and impact resistance, should not corrode the surrounding materials, should not be brittle at low temperatures within the specified temperature range, and should have good chemical stability at high temperatures. 4.4
Specifications and properties
Main specifications and properties shall comply with the requirements of Table 1: Table 1
Specifications and properties
Carbon steel wire
Bundle 785
Single force test:
Tensile strength N/m
Yield strength oa.2, N/mm, or service load, kN Elongation, %
Bending test:
The number of times shall not be less than
Bending radius R, mm
Elastic modulus, N/mm2
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1×7—012.0
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1000#Relaxation value, %
(Initial load is 70% of breaking load)||tt| |Not more than
Area, mm2
Quantity, kg/m
Weight of anti-corrosion grease, g/mMaximum
Thickness of high-density polyethylene sheath, mm
Friction test:
Seasonal friction coefficient u between unbonded prestressed tendons and wall
Considering the influence of local deviation of unbonded prestressed tendons and wall per meter length on friction coefficient K
Grade I relaxation
Grade + relaxation
Note: (1) * refers to the service load, which is 85% of the breaking load of the whole steel strand; Carbon steel wire
Bundle 785
Specifications and properties
Steel strand
1×
[email protected](2) Prestressed steels of other strengths and diameters can be supplied according to different uses and agreed upon by both parties. 4.5 Production of unbonded prestressed tendons
The coating of steel wire, wire bundle coating layer and sheath production should be completed at one time, and should preferably not be extruded using an extruder. After forming, the unbonded prestressed tendons shall meet the following requirements: 4.5.1
The coating layer of grease shall be sufficient and full, and continuous along the entire length of the prestressed tendons. The amount of grease per linear meter shall meet the requirements of Table 1 of Article 4.4 of this standard:
4.5.2 The sheath shall be uniform in thickness, and its thickness shall meet the requirements of Table 1 of Article 4.4 of this standard; 4.5.3 Unbonded prestressed tendons shall be produced continuously, and each steel wire in the steel strand or steel wire bundle shall consist of a whole steel wire, without joints and dead bends;
4.54 Unbonded prestressed tendons shall have good straightness, and the inner diameter of the coil shall not be less than 2000mm4.6
Appearance requirements
The sheath shall be smooth and free of cracks and obvious folds when leaving the factory. 5 Test methods and number of samples
5.1 Appearance requirements shall be inspected by naked eye, and the entire length shall be inspected. 5.2 Method for measuring the amount of grease in the coating layer
Each shift randomly selects three samples from the finished product. For each sample, take a 1m long unbonded prestressed tendon and weigh it with a balance with an accuracy of 1.0g (W). Then remove the grease on the sheath and steel strand or wire bundle and weigh it (W2). The weight of grease per linear meter W3=W1-W2. Take the average of the three sample measurement results. Engineering Construction Standard Full Text Information System
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5.3 Method for measuring the thickness of the sheath
Each shift randomly selects three sections of samples from the finished product, wipes off the grease, and uses a vernier caliper with an accuracy of 0.1mm to measure the two thicknesses at the thinnest and thickest parts of each section of the port, and takes the arithmetic average. 5.4 Test method for friction coefficient μ and k value. The length of the concrete member with straight reinforcement and curved (parabola) reinforcement shall not be less than 5000mm. Precision pressure sensors are respectively set at the tensioning end and the fixed end (non-tensioning end). When tensioning, the K value is first calculated according to the difference in tension at both ends, and then the K value is calculated according to the curved reinforcement. The tensioning end of each hole is replaced twice, a total of 4 times, and the arithmetic mean value is calculated. Steel should be inspected in batches according to batch number and diameter when entering the factory. The inspection content includes checking marks and appearance inspection. The inspection methods for tensile strength, yield load or yield strength (oo2), elongation, number of wire bending times and diameter of steel shall be carried out in accordance with the relevant provisions of G5223, GB2103 and GB228. 6 Inspection rules Inspection classification Product inspection is divided into factory inspection and type inspection. Factory inspection
Factory inspection is conducted by the quality supervision department of the production unit, and the batches can only be shipped after passing the inspection6.2.2
Factory inspection items
Tensile strength of steel strands or wires, yield load or yield strength (02), elongation, number of bending times and diameter of steel wires,
Amount of grease used in coating layer;
Thickness of sheath;
Appearance.
Type inspection
Type inspection is to conduct a comprehensive assessment of product quality. All items in Table 1 of Article 4.4 of this standard shall be inspected. 6.3.1
Type inspection is required in any of the following situations: When the product is converted:
When there are major changes in raw materials, processes, etc.;
When major equipment failures occur during the transformation of production equipment or during the production process; When the product is resumed after a long period of suspension; When there are major differences between the factory inspection and the last type inspection; When the national quality supervision agency proposes to conduct type inspection. f.
6.4 Batch rules
Steel strands and unbonded prestressed steel wire bundles shall be inspected and accepted in batches. Each batch shall consist of steel strands and unbonded prestressed steel wire bundles produced with the same steel grade, the same specification and the same production system. Each order from each user is an inspection batch, and the weight of each batch shall not exceed 30t.
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7 Judgment rules and re-inspection
When all inspection items meet the technical requirements of this standard, the batch of products shall be qualified; when there are unqualified items in the inspection results, the unqualified items shall be re-sampled and re-inspected with double sampling. If the re-inspection results are still unqualified, the batch of products shall be unqualified.
8 Packaging, marking, purchase, storage, and transportation
Packaging and marking
Products shipped out of the factory should have a quality guarantee, and there should be a clear label on the product, indicating the product name, specification mark, quantity, trademark, factory name, and production date. Products must be properly packaged before leaving the factory. When there are special requirements, the packaging materials and packaging methods shall be determined by negotiation between the supply and demand parties.
8.2 Storage and transportation
Unbonded prestressed tendons should be classified into bundles and disks according to different specifications and neatly stacked in a well-ventilated warehouse during the stacking of finished products; when stacked in the open air, it is strictly forbidden to place them in places affected by heat, and they should be placed on the bracket without direct contact with the ground, and covered with rain cloth. It is strictly forbidden to collide or step on them during the stacking of finished products. Unbonded prestressed tendons of steel strands should be transported in disks, and unbonded prestressed tendons of carbon steel wire bundles can be transported in disks or straight strips. During transportation and loading and unloading, the slings should be wrapped with rubber, nylon belts and other materials, and should be loaded and unloaded with care. It is strictly forbidden to throw or drag on the ground, and it is strictly forbidden to damage unbonded prestressed tendons with sharp objects. Additional notes,
This standard is proposed by the Standard and Norms Institute of the Ministry of Construction of the People's Republic of China. This standard is under the jurisdiction of the China Academy of Building Research, the technical management unit of construction engineering standards of the Ministry of Construction. The Institute of Building Structures of the China Academy of Building Research, the Cunlian Prestressed Machinery Factory of the Beijing Institute of Building Engineering, and the Changsha Oil Factory of Hunan Province are responsible for drafting this standard. The main drafters of this standard are: Tao Xuekang, Wang Ni, Li Guoli, Dai Jinting, Lu Jin, Peng Binkun, and Huo Xiaoming. This standard is entrusted to the China Academy of Building Research for interpretation. 3K888
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