1、Standard Specification for Steel Strand, Uncoated Seven-Wire for Concrete Reinforcement AASHTO Designation: M 203M/M 203-12 (2016) Release: Group 2 (June 2016) ASTM Designation: A416/A416M-10 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249
2、Washington, D.C. 20001TS-4g M 203M/M 203-1 AASHTO Standard Specification for Steel Strand, Uncoated Seven-Wire for Concrete Reinforcement AASHTO Designation: M 203M/M 203-12 (2016) Release: Group 2 (June 2016) ASTM Designation: A416/A416M-10 1. SCOPE 1.1. This specification covers two types and two
3、grades of steel strand, uncoated seven-wire for use in pretensioned and post-tensioned prestressed concrete construction. The two types of strand are low-relaxation and stress-relieved (normal-relaxation). Low-relaxation strand shall be regarded as the standard type. Stress-relieved (normal-relaxati
4、on) strand will not be furnished unless specifically ordered or by arrangement between purchaser and supplier. Grade 1725 250 and Grade 1860 270 have minimum ultimate strengths of 1725 MPa 250 ksi and 1860 MPa 270 ksi, respectively, based on the nominal area of the strand. 1.2. The values stated in
5、either inch-pound units or SI units are to be regarded 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 system must be used independently of the other. Combining values from the two systems may resul
6、t 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 prestressed ground anchors. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: T 244, Mechanical Testin
7、g 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 Ground Anchors E328, Standard Test Methods for Stress Relaxation Tests for Materials and Str
8、uctures 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 Standards: MIL-STD-129, Marking for Shipment and Storage MIL-STD-163, Steel Mill Products Preparation for Shipment and Storage 2016 by the Amer
9、ican Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g M 203M/M 203-2 AASHTO 2.5. Federal Standard: Fed. Std. No. 123, Marking for Shipments (Civil Agencies) 3. TERMINOLOGY 3.1. Description of Term Specific to This Stan
10、dard: 3.1.1. strandall strand shall be of the seven-wire type having a center wire enclosed tightly by six helically placed outer wires with a uniform pitch of not less than 12 and not more than 16 times the nominal diameter of the strand. 3.1.1.1. DiscussionThe direction of lay may be either right
11、or left hand; however, strands of different lays should not be spliced together. 4. ORDERING INFORMATION 4.1. Orders for seven-wire low-relaxation or stress-relieved (normal-relaxation) strand under this specification should include the following information: 4.1.1. Quantity (meters) feet, 4.1.2. Di
12、ameter of strand, 4.1.3. Grade of strand, 4.1.4. Type of strand, 4.1.5. Packaging, 4.1.6. AASHTO designation and year of issue, and 4.1.7. Special requirements, if any. 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 360
13、0-m 12,000-ft reelless packs conforming to M 203M/M 203-_. 5. MATERIALS AND MANUFACTURE 5.1. Base MetalThe base metal shall be carbon steel of such quality that when drawn to wire, fabricated into strand, and then thermally treated, it shall have the properties and characteristics prescribed in this
14、 specification. 5.2. WireThe wire from which 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 mechanical properties only; the chemical composition of all wires or any individual wire is not pertinent to thi
15、s application, and heat identity is not necessarily maintained. It is possible that wire from more than one heat may be used in the manufacture of a reel or pack. Traceability is based on pack identity as maintained and reported by the manufacturer. 5.3. TreatmentAfter stranding, low-relaxation stra
16、nd shall be subjected to a continuous thermal-mechanical treatment to produce the prescribed mechanical properties. For stress-relieved 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g M 203M/M 203
17、-3 AASHTO (normal-relaxation) strand, only thermal treatment is necessary. Temper colors that may result from the thermal operation are considered normal for the finished appearance of this strand. 6. MECHANICAL PROPERTIES 6.1. Methods of testing for mechanical properties are described in Appendix A
18、7 of T 244. Low-relaxation strand shall also be tested as prescribed in ASTM E328. 6.2. Breaking StrengthThe breaking strength of the finished strand shall conform to the requirements prescribed in Table 1. 6.3. Yield StrengthYield strength in kN pounds shall be measured at 1 percent extension under
19、 load. The minimum yield strength shall be 90 percent for low-relaxation strand and 85 percent for stress-relieved normal-relaxation strand of the breaking strength listed in Table 1. Initial loads for the test and minimum yield strengths are listed in Table 2. Table 1Breaking Strength Requirements
20、Strand Designation No. Nominal Diameter of Strand, mm in. Minimum Breaking Strength of Strand, kN lbf Nominal Steel Area of Strand, mm2 in.2 Nominal Mass of Strand, g/m lb/1000 ft Grade 1725 250 6 6.4 0.250 40.0 9,000 23.2 0.036 182 122 8 7.9 0.313 64.5 14,500 37.4 0.058 294 197 9 9.5 0.375 89.0 20,
21、000 1.6 0.080 405 272 11 11.1 0.438 120.1 27,000 69.7 0.108 548 367 13 12.7 0.500 160.1 36,000 92.9 0.144 730 490 15 15.2 0.600 240.2 54,000 139.4 0.216 1094 737 Grade 1860 270 9 9.53 0.375 102.3 23,000 54.8 0.085 432 290 11 11.11 0.438 137.9 31,000 74.2 0.115 582 390 13 12.70 0.500 183.7 41,300 98.
22、7 0.153 775 520 13a 13.20 0.520 200.2 45,000 107.7 0.167 844 568 14 14.29 0.563 230.0 51,700 123.9 0.192 970 651 15 15.24 0.600 260.7 58,600 140.0 0.217 1102 740 16 15.75 0.620 277.4 62,370 149.2 0.231 1173 788 18 17.78 0.700 353.2 79,400 189.7 0.294 1487 1000 2016 by the American Association of Sta
23、te Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g M 203M/M 203-4 AASHTO Table 2Yield Strength Requirements Strand Designation No. Nominal Diameter of Strand mm in. Initial Load, kN lbf Minimum Load at 1% Extension, kN lbf Low- Relaxation
24、 Normal- Relaxation Grade 1725 250 6 6.4 0.250 4.0 900 36.0 8,100 34.0 7,650 8 7.9 0.313 6.5 1,450 58.1 13,050 54.7 12,300 9 9.5 0.375 8.9 2,000 80.1 18,000 75.6 17,000 11 11.1 0.438 12.0 2,700 108.1 24,300 102.3 23,000 13 12.7 0.500 16.0 3,600 144.1 32,400 136.2 30,600 15 15.2 0.600 24.0 5,400 216.
25、2 48,600 204.2 45,900 Grade 1860 270 9 9.53 0.375 10.2 2,300 92.1 20,700 87.0 19,550 11 11.11 0.438 13.8 3,100 124.1 27,900 117.2 26,350 13 12.70 0.500 18.4 4,130 165.3 37,170 156.1 35,100 13a 13.20 0.520 20.0 4,500 180.1 40,500 170.1 38,250 14 14.29 0.563 23.0 5,170 207.0 46,530 195.5 43,950 15 15.
26、24 0.600 26.1 5,860 234.6 52,740 221.5 49,800 16 15.75 0.620 27.7 6,237 249.7 56,133 235.9 53,015 18 17.78 0.700 35.3 7,940 318.0 71,500 300.2 67,500 6.3.1. The extension under load shall be measured by an extensometer calibrated with the smallest division not larger than 0.0001 mm/mm 0.0001 in./in.
27、 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 the percent extension or movement betwe
28、en 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 PropertiesLow-relaxation strand shall have relaxation losses of not more than 2.5 percent when initially loaded to 70 percent of specified minimum break
29、ing 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 under the conditions listed in Sections 6.5.1 through 6.5.7. 6.5.1. If required, relaxation evidence shall be provided from the manufacturers records of tests
30、on similarly dimensioned strand of the same grade. 6.5.2. The temperature of the test specimen shall be maintained at 20 2C 68 3.5F. 6.5.3. The test specimen shall not be subjected to loading prior to the relaxation test. 6.5.4. The initial load shall be applied uniformly over a period of not less t
31、han 3 min and not more than 5 min, and the gauge length shall be maintained constant; load-relaxation readings shall commence 1 min after application of the total load. 6.5.5. Overstressing of the test specimen during the loading operation shall not be permitted. 6.5.6. The duration of the test shal
32、l be 1000 h or a shorter period of at least 200 h, provided it can be shown by records that an extrapolation of the shorter period test results to 1000 h will provide similar relaxation values as the full 1000-h test. 2016 by the American Association of State Highway and Transportation Officials. Al
33、l rights reserved. Duplication is a violation of applicable law.TS-4g M 203M/M 203-5 AASHTO 6.5.7. The test gauge length should be at least 60 times the nominal diameter. If this gauge length exceeds the capacity of the extensometer or testing machine, then it shall be permitted to substitute a gaug
34、e length of 40 times the nominal strand diameter. 7. DIMENSIONS AND PERMISSIBLE VARIATIONS 7.1. The size of the finished strand shall be expressed as the nominal diameter of the strand in millimeters inches. 7.2. The diameter of the center wire of any strand shall be larger than the diameter of any
35、outer wire in accordance with Table 3. Table 3Diameter Relation between Center and Outer Wires Strand Designation No. Nominal Diameter of Strand Minimum Difference between Center Wire Diameter and Diameter of Any Outer Wire mm in. mm in. Grade 1725 250 6 6.4 0.250 0.025 0.001 8 7.9 0.313 0.038 0.001
36、5 9 9.5 0.375 0.051 0.002 11 11.1 0.438 0.064 0.0025 13 12.7 0.500 0.076 0.003 15 15.2 0.600 0.102 0.004 Grade 1860 270 9 9.53 0.375 0.0508 0.002 11 11.11 0.438 0.0635 0.0025 13 12.70 0.500 0.0762 0.003 13a 13.20 0.520 0.0762 0.003 14 14.29 0.563 0.0889 0.0035 15 15.24 0.600 0.1016 0.004 16 15.75 0.
37、620 0.1016 0.004 18 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. All Grade 1860 270 strand shall conform to a size t
38、olerance 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 diameter differences of the individual wires and the dia
39、meters of the strand are within the tolerances specified. 7.4. It shall be permitted to furnish, under this specification, specially dimensioned low-relaxation and stress-relieved normal-relaxation strands with nominal diameters up to 19 mm 0.750 in. The breaking strength shall be defined, and the y
40、ield strength, as defined in Section 6.3, shall not be less than 90 percent and 85 percent of the specified minimum breaking strength for low-relaxation and stress-relieved normal-relaxation strands, respectively. All other requirements shall apply. 2016 by the American Association of State Highway
41、and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g M 203M/M 203-6 AASHTO 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 completed strand unless specifically permitted
42、 by the purchaser. 8.1.2. During the process of manufacture of individual wires for stranding, welding 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 fir
43、st die in the wire drawing except as provided in Section 8.1.3. 8.1.3. During fabrication of the 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
44、 as “Weldless,” a product free of welds shall be furnished. When “Weldless” is specified, the strand 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 not consistent with good comme
45、rcial stranding practice. 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 can 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
46、 sufficient to cause pits visible to the unaided eye, shall not be cause for rejection. Note 3Guidance for evaluating the degree of rusting on prestressed concrete strand is presented in Sason.19. SAMPLING 9.1. Test specimens cut from either end of the strand package are permitted. Any specimen foun
47、d to contain a wire joint should be discarded and a new specimen obtained. 10. NUMBER OF TESTS 10.1. One specimen for test shall be taken from each 18-Mg 20-ton production lot of finished strand, and tested for breaking strength, yield strength, and elongation. 11. INSPECTION 11.1. If outside inspec
48、tion is required, the manufacturer shall afford the inspector representing the purchaser all reasonable facilities to satisfy 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 operation of the works. Note 4The purchaser should state, at the time of order, whether outside inspection is required or waived.
