1、Standard Specification for Steel Strand, Low-Relaxation Uncoated Seven-Wire for Concrete Reinforcement AASHTO Designation: M 203M/M 203-18 Technical Section: 4f, Metals Release: Group 2 (June) ASTM Designation: A416/A416M-17 American Association of State Highway and Transportation Officials 444 Nort
2、h Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-4f M 203M/M 203-1 AASHTO Standard Specification for Steel Strand, Low-Relaxation Uncoated Seven-Wire for Concrete Reinforcement AASHTO Designation: M 203M/M 203-18 Technical Section: 4f, Metals Release: Group 2 (June) ASTM Designation: A416/
3、A416M-17 1. SCOPE 1.1. This specification covers two grades of uncoated low-relaxation, seven-wire steel strand for use in pretensioned and post-tensioned prestressed concrete construction. Grade 1725 250 and Grade 1860 270 have minimum ultimate strengths of 1725 MPa 250 ksi and 1860 MPa 270 ksi, re
4、spectively, based on the nominal area of the strand. 1.2. The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the inch-pound units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each syste
5、m must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. 1.3. The supplementary requirements in S1 shall be specified for 15.24-mm- 0.600-in.- diameter uncoated seven-wire steel strand if needed for applications in prestres
6、sed ground anchors. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: T 244, Mechanical Testing of Steel Products 2.2. ASTM Standards: A981/A981M, Standard Test Method for Evaluating Bond Strength for 0.600-in. 15.24-mm Diameter Steel Prestressing Strand, Grade 270 1860, Uncoated, Used in Prestressed Gr
7、ound Anchors A1061/A1061M, Standard Test Methods for Testing Multi-Wire Steel Prestressing Strand 2.3. IEEE/ASTM Standard: SI 10, American National Standard for Use of the International System of Units (SI): The Modern Metric System 2.4. Military Standard: MIL-STD-129, Marking for Shipment and Stora
8、ge 2.5. Federal Standard: Fed. Std. No. 123, Marking for Shipments (Civil Agencies) 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4f M 203M/M 203-2 AASHTO 3. TERMINOLOGY3.1. Description of Term Spe
9、cific to This Standard:3.1.1. strandall strand shall be of the seven-wire type having a center wire enclosed tightly by sixhelically placed outer wires with a uniform pitch of not less than 12 and not more than 16 times thenominal diameter of the strand.3.1.1.1. DiscussionThe direction of lay is eit
10、her right-handed or left-handed.4. ORDERING INFORMATION4.1. Orders for seven-wire strand under this specification should include the following information:4.1.1. Quantity (meters) feet,4.1.2. Nominal diameter of strand,4.1.3. Grade of strand,4.1.4. Weldless, if desired (8.1),4.1.5. Load-elongation c
11、urve, if desired (13.2),4.1.6. Packaging,4.1.7. AASHTO designation and year of issue, and4.1.8. Supplementary Requirement S1, if desired.Note 1A typical ordering description is as follows: 25 600 m 84,000 ft, 13 mm 0.5 in.,Grade 1860 270 low-relaxation strand, in 3600-m 12,000-ft reelless packs conf
12、orming toM 203M/M 203.5. MATERIALS AND MANUFACTURE5.1. Base MetalThe base metal shall be carbon steel of such quality that when drawn to wire, fabricatedinto strand, and then thermally treated, shall have the properties and characteristics prescribed in thisspecification.5.2. WireThe wire from which
13、 the strand is to be fabricated shall be round and have a dry-drawn finish.Note 2This product is a composite of seven wires and is produced to meet the prescribedmechanical properties. The chemical composition of all wires or any individual wire is not pertinentto this application, and heat identity
14、 is not necessarily maintained. It is possible that wire from morethan one heat may be used in the manufacture of a reel or reelless pack. Traceability is based onidentity of reels or reelless packs as maintained and reported by the manufacturer.5.3. TreatmentAfter stranding, low-relaxation strand s
15、hall be subjected to a continuous thermal-mechanical treatment to produce the prescribed mechanical properties. Temper colors that may resultfrom the thermal-mechanical treatment are considered normal for the finished appearance of thisstrand. 2018 by the American Association of State Highway and Tr
16、ansportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4f M 203M/M 203-3 AASHTO 6. MECHANICAL PROPERTIES6.1. Methods of testing for mechanical properties shall be conducted in accordance with ASTMA1061/A1061M.6.2. Breaking StrengthThe breaking strength of the fi
17、nished strand shall conform to the requirementsprescribed in Table 1.6.3. Yield StrengthYield strength in kN pounds shall be measured at 1 percent extension under load.The minimum yield strength shall be 90 percent of the breaking strength listed in Table 1. Initial loadsfor the test and minimum yie
18、ld strengths are listed in Table 2.Table 1Breaking Strength Requirements Nominal Diameter of Strand, mm in. Minimum Breaking Strength of Strand, kN lbf Nominal Steel Area of Strand, mm2in.2 Nominal Mass of Strand, g/m lb/1000 ft Grade 1725 250 6.4 0.250 40.0 9,000 23.2 0.036 182 122 7.9 0.313 64.5 1
19、4,500 37.4 0.058 294 197 9.5 0.375 89.0 20,000 51.6 0.080 405 272 11.1 0.438 120.1 27,000 69.7 0.108 548 367 12.7 0.500 160.1 36,000 92.9 0.144 730 490 15.2 0.600 240.2 54,000 139.4 0.216 1094 737 Grade 1860 270 9.53 0.375 102.3 23,000 54.8 0.085 432 290 11.11 0.438 137.9 31,000 74.2 0.115 582 390 1
20、2.70 0.500 183.7 41,300 98.7 0.153 775 520 13.20 0.520 200.2 45,000 107.7 0.167 844 568 14.29 0.563 230.0 51,700 123.9 0.192 970 651 15.24 0.600 260.7 58,600 140.0 0.217 1102 740 15.75 0.620 279.3 62,800 149.2 0.231 1200 780 17.78 0.700 353.2 79,400 189.7 0.294 1500 1000 Table 2Yield Strength Requir
21、ements Nominal Diameter of Strand mm in. Initial Load, kN lbf Minimum Load at 1% Extension, kN lbf Grade 1725 250 6.4 0.250 4.0 900 36.0 8,100 7.9 0.313 6.5 1,450 58.1 13,050 9.5 0.375 8.9 2,000 80.1 18,000 11.1 0.438 12.0 2,700 108.1 24,300 12.7 0.500 16.0 3,600 144.1 32,400 15.2 0.600 24.0 5,400 2
22、16.2 48,600 Grade 1860 270 9.53 0.375 10.2 2,300 92.1 20,700 11.11 0.438 13.8 3,100 124.1 27,900 12.70 0.500 18.4 4,130 165.3 37,170 13.20 0.520 20.0 4,500 180.1 40,500 14.29 0.563 23.0 5,170 207.0 46,530 15.24 0.600 26.1 5,860 234.6 52,740 15.75 0.620 27.7 6,237 251.4 56,520 17.78 0.700 35.3 7,940
23、318.0 71,500 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4f M 203M/M 203-4 AASHTO 6.3.1. The extension under load shall be measured by an extensometer calibrated with the smallest division not la
24、rger than 0.0001 mm/mm 0.0001 in./in. of gauge length. 6.4. ElongationThe total elongation under load shall not be less than 3.5 percent using a gauge length of not less than 600 mm 24 in. It shall be permissible to determine the total elongation value by adding to the 1.0 percent yield extension th
25、e percent extension or movement between the jaws gripping the strand after yield determination. The percent is calculated on the new base length of jaw-to-jaw distance. 6.5. Relaxation PropertiesStrand shall have relaxation losses of not more than 2.5 percent when initially loaded to 70 percent of s
26、pecified minimum breaking strength or not more than 3.5 percent when loaded to 80 percent of specified minimum breaking strength of the strand after 1000 h tested. 7. DIMENSIONS AND PERMISSIBLE VARIATIONS 7.1. The size of the finished strand shall be expressed as the nominal diameter of the strand i
27、n millimeters inches. 7.2. The diameter of the center wire of any strand shall be larger than the diameter of any outer wire in accordance with Table 3. Table 3Diameter Relation between Center and Outer Wires Nominal Diameter of Strand mm in. Minimum Difference between Center Wire Diameter and Diame
28、ter of Any Outer Wire mm in. Grade 1725 250 6.4 0.250 0.025 0.001 7.9 0.313 0.038 0.0015 9.5 0.375 0.051 0.002 11.1 0.438 0.064 0.0025 12.7 0.500 0.076 0.003 15.2 0.600 0.102 0.004 Grade 1860 270 9.53 0.375 0.0508 0.002 11.11 0.438 0.0635 0.0025 12.70 0.500 0.0762 0.003 13.20 0.520 0.0762 0.003 14.2
29、9 0.563 0.0889 0.0035 15.24 0.600 0.1016 0.004 15.75 0.620 0.1016 0.004 17.78 0.700 0.1143 0.0045 7.3. Permissible Variations in Diameter: 7.3.1. All Grade 1725 250 strand shall conform to a size tolerance of 0.40 mm 0.016 in. from the nominal diameter measured across the crowns of the wires. 7.3.2.
30、 All Grade 1860 270 strand shall conform to a size tolerance of +0.65 mm, 0.15 mm +0.026 in., 0.006 in. from the nominal diameter measured across the crowns of the wire. 7.3.3. Variation in cross-sectional area and in unit stress resulting therefrom shall not be cause for rejection provided the diam
31、eter differences of the individual wires and the diameters of the strand are within the tolerances specified. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4f M 203M/M 203-5 AASHTO 7.4. It shall be
32、 permitted to furnish, under this specification, specially dimensioned strands with nominal diameters up to 19 mm 0.750 in. The breaking strength shall be defined, and the yield strength, as defined in Section 6.3, shall not be less than 90 percent of the specified minimum breaking strength. All oth
33、er requirements shall apply. 8. WORKMANSHIP, FINISH, AND APPEARANCE 8.1. Joints: 8.1.1. There shall be no strand joints or strand splices in any length of the finished strand unless specifically permitted by the purchaser. 8.1.2. During the process of manufacture of individual wires for stranding, w
34、elding shall be permitted only prior to or at the time of the last thermal treatment, for example, patenting or control cooling. There shall be no welds in the wire after it has been drawn through the first die in the wire drawing except as provided in Section 8.1.3. 8.1.3. During fabrication of the
35、 strand, butt-welded joints are permitted in the individual wires, provided there shall not be more than one such joint in any 45-m 150-ft section of the completed strand. 8.1.4. When specifically ordered as “Weldless,” a product free of welds shall be furnished. When “Weldless” is specified, the st
36、rand is produced as one continuous length with no welds as allowed by Section 8.1.3. 8.2. The finished strand shall be uniform in diameter and shall be free of imperfections. 8.3. When the strand is cut without seizings, the wire shall not fly out of position. If any wire flies out of position and c
37、an be replaced by hand, the strand will be considered satisfactory. 8.4. The strand shall not be oiled or greased. Slight rusting, provided it is not sufficient to cause pits visible to a person with normal or corrected vision, shall not be cause for rejection. Note 3Guidance for evaluating the degr
38、ee of rusting on prestressed concrete strand is presented in Sason.19. SAMPLING 9.1. Test specimens cut from either end of the reel or reelless pack are permitted. Any specimen found to contain a wire joint should be discarded and a new specimen obtained. 10. NUMBER OF TESTS 10.1. One specimen for t
39、est shall be taken from each 27-Mg 30-ton production lot of finished strand, and tested for breaking strength, yield strength, and elongation. 11. INSPECTION 11.1. If outside inspection is required, the manufacturer shall afford the inspector representing the purchaser all reasonable facilities to s
40、atisfy that the material is being furnished in accordance with this specification. All tests and inspections shall be made at the place of manufacture prior to shipment, unless otherwise agreed on at the time of purchase, and shall be so conducted as not to interfere unnecessarily with the manufactu
41、rers operations. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4f M 203M/M 203-6 AASHTO 12. REJECTION 12.1. Failure of any test specimen to comply with the requirements of the specification shall c
42、onstitute grounds for rejection of the lot represented by the specimen. 12.2. The lot shall be resubmitted for inspection by testing a specimen from each reel or reelless pack and sorting out nonconforming material. 12.3. In case there is a reasonable doubt in the initial testing as to the ability o
43、f the strand to meet any requirement of this specification, two additional tests shall be made on a specimen of strand from the same reel or pack, and if failure occurs in either of these tests, the strand shall be rejected. 13. CERTIFICATION 13.1. If outside inspection is not required, a manufactur
44、ers certification that the material has been tested in accordance with and meets the requirements of this specification shall be the basis of acceptance of the material. The certification shall include the specification number, year of issue, and revision letter, if any. 13.2. The manufacturer shall
45、, when requested in the order, furnish a representative load-elongation curve for each size and grade of strand shipped. 13.3. When the modulus of elasticity of a seven-wire strand is provided, the cross-sectional area used to compute that modulus shall also be provided. The area provided in the cer
46、tification shall be the area used to calculate the modulus of elasticity. 13.4. A material test report, certificate of inspection, or similar document printed from or used in electronic form from an electronic data interchange (EDI) transmission shall be regarded as having the same validity as a cou
47、nterpart printed in the certifiers facility. The content of the EDI- transmitted document must meet the requirements of the invoked AASHTO standard(s) and conform to any existing EDI agreement between the purchaser and the supplier. Notwithstanding the absence of a signature, the organization submit
48、ting the EDI transmission is responsible for the content of the report. Note 4The industry definition as invoked here is: EDI is the computer-to-computer exchange of business information in a standard format such as ANSI ASC X12. 14. PACKAGING AND MARKING 14.1. The strand shall be furnished on reels or in reelless packs having a minimum core diameter of 610 mm 24 in. unless otherwise specified by the purchaser. Lengths on reels or in reelless packs shall be as agreed on at the time of purchase. The strand shall be well protected against mechanical injury in shipping as
