1、Standard Specification for Uncoated High-Strength Steel Bars for Prestressing Concrete AASHTO Designation: M 275M/M 275-08 (2016) Release: Group 2 (June 2016) ASTM Designation: A722/A722M-07 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 W
2、ashington, D.C. 2000TS-4g M 275M/M 275-1 AASHTO Standard Specification for Uncoated High-Strength Steel Bars for Prestressing Concrete AASHTO Designation: M 275M/M 275-08 (2016) Release: Group 2 (June 2016) ASTM Designation: A722/A722M-07 1. SCOPE 1.1. This specification covers uncoated high-strengt
3、h steel bars intended for use in pretensioned and posttensioned prestressed concrete construction or in prestressed ground anchors. Bars are of a minimum ultimate tensile strength level of 1035 MPa 150,000 psi. 1.2. Two types of bars are provided: Type I bar has a plain surface and Type II bar has s
4、urface deformations. 1.3. Supplementary requirements of an optional nature are provided. They shall apply only when specified by the purchaser. 1.4. This specification is applicable for orders in either SI units (M 275M) or in inch-pound units (M 275). SI units and inch-pound units are not necessari
5、ly equivalent. Inch-pound units are shown in brackets in the text for clarity, but they are the applicable values when the material is ordered to M 275. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: T 244, Mechanical Testing of Steel Products T 285, Bend Test for Bars for Concrete Reinforcement 2.2
6、. ASTM Standards: A700-05, Standard Practices for Packaging, Marking, and Loading Methods for Steel Products for Shipment (withdrawn 2014) E30-89, Test Methods for Chemical Analysis of Steel, Cast Iron, Open-Hearth Iron, and Wrought Iron (withdrawn 1995) 2.3. Military Standard: MIL-STD-129, Marking
7、for Shipment and Storage 2.4. Federal Standard: Fed. Std. 123, Marking for Shipment (Civil Agencies) 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g M 275M/M 275-2 AASHTO 3. ORDERING INFORMATION 3
8、.1. Orders for material under this specification should include the following information: 3.1.1. Quantity (mass); 3.1.2. Name of material (uncoated high-strength bars for prestressing concrete); 3.1.3. AASHTO designation and year of issue; 3.1.4. Size and length; 3.1.5. Type; 3.1.6. Special inspect
9、ion requirements, if desired (Section 12); 3.1.7. Special preparation for delivery, if desired (Section 11); 3.1.8. Load-elongation curve, if required (Section 15); and 3.1.9. Supplementary requirements, if desired. Note 1A typical ordering description is as follows: 50 uncoated high-strength bars f
10、or prestressing concrete to M 275M/M 275-_; 26-mm diameter, 12.3 m long, Type II; packed in accordance with ASTM A700-05; meeting supplementary bending properties. 50 uncoated high-strength bars for prestressing concrete to M 275M/M 275-_; 1-in. diameter, 40 ft, 6 in. long, Type II; packed in accord
11、ance with ASTM A700-05; meeting supplementary bending properties. 4. MATERIALS AND MANUFACTURE 4.1. The bars shall be rolled from properly identified heats of ingot cast or strand-cast steel. The standard sizes and dimensions of Type I and Type II bars shall be those listed in Table 1 and Table 2, r
12、espectively. Table 1Dimensions for Type I (Plain) Bar Nominal Diameter Nominal Weight Nominal Areaamm in. kg/m lb/ft mm2in.219 3/42.23 1.50 284 0.44 22 7/83.04 2.04 387 0.60 25 1 3.97 2.67 503 0.78 29 11/85.03 3.38 639 0.99 32 11/46.21 4.17 794 1.23 35 13/87.52 5.05 955 1.48 aThe nominal area is det
13、ermined from the nominal diameter in inches. Values have been converted from inch-pound units to metric units. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g M 275M/M 275-3 AASHTO Table 2Dimensio
14、ns for Type II (Deformed) Bar Nominal DiameteraNominal Weight Nominal Areabmm in. kg/m lb/ft mm2in.215 5/81.46 0.98 181 0.28 20 3/42.22 1.49 271 0.42 26 1 4.48 3.01 548 0.85 32 11/46.54 4.39 806 1.25 36 13/88.28 5.56 1019 1.58 46 13/413.54 9.10 1664 2.58 65 21/227.10 18.20 3331 5.16 aNominal diamete
15、rs are for identification only. Values have been converted from metric to inch-pound units. bThe nominal area is determined from the bar weight less 3.5 percent for the ineffective weight of the deformation. 4.2. The bars shall be subjected to cold-stressing to not less than 80 percent of the minimu
16、m ultimate strength, and then shall be stress-relieved, to produce the prescribed mechanical properties. 5. CHEMICAL COMPOSITION 5.1. An analysis of each heat of steel shall be made by the manufacturer from test samples taken during the pouring of each heat. 5.1.1. Choice and use of chemical composi
17、tion and alloying elements, to produce the mechanical properties of the finished bar prescribed in Section 6.2, shall be made by the manufacturer, subject to the limitations in Section 5.1.2. 5.1.2. On heat analysis, phosphorus and sulfur shall not exceed the following: Phosphorus 0.040% Sulfur 0.05
18、0% 5.2. A product analysis may be made by the purchaser from the finished bar representing each cast or heat of steel. The phosphorus and sulfur contents thus determined shall not exceed the limits specified in Section 5.1.2 by 0.008 percent. 5.3. ASTM E30-89 (withdrawn 1995) shall be used for refer
19、ee purposes. 6. MECHANICAL PROPERTIES 6.1. All testing for mechanical properties shall be performed in accordance with the requirements of T 244 Methods and Definitions. 6.2. Tensile Properties: 6.2.1. Finished bars shall have a minimum ultimate tensile strength of 1035 MPa 150,000 psi. 6.2.2. The m
20、inimum yield strength of Type I and Type II bars shall be 85 percent and 80 percent, respectively, of the minimum ultimate tensile strength of the bars. The yield strength shall be determined by either of the methods described in T 244; however, in the extension under load method, the total strain s
21、hall be 0.7 percent, and in the offset method the offset shall be 0.2 percent. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g M 275M/M 275-4 AASHTO 6.2.3. The minimum elongation after rupture sha
22、ll be 4.0 percent in a gauge length equal to 20 bar diameters or 7.0 percent in a gauge length equal to 10 bar diameters. 6.3. Test SpecimensTension tests shall be made using full-size bar test specimens. Machined reduced section test specimens are not permitted. All unit stress determinations shall
23、 be based on the nominal area shown in Table 1 or the effective area shown in Table 2. 6.4. Number of TestsThe number of tensile specimens tested shall be one from each 36 Mg 39 tons or fraction thereof of each size of bar rolled from each heat but not fewer than two from each heat. The specimens sh
24、all be randomly selected following the final processing operation. 6.5. Retests: 6.5.1. If any tensile property of any tension test specimen is less than that specified, and any part of the fracture is outside the middle third of the gauge length, as indicated by scribe scratches marked on the speci
25、men before testing, a retest shall be allowed. 6.5.2. If the results of an original tension test fail to meet specified requirements, two additional tests shall be made on samples of bar from the same heat and bar size, and if failure occurs in either of these tests, the bar size from that heat shal
26、l be rejected. 6.5.3. If any test specimen fails because of mechanical reasons such as failure of testing equipment, it shall be discarded and another specimen taken. 6.5.4. If any test specimen develops flaws, it shall be discarded and another specimen of the same size bar from the same heat substi
27、tuted. 7. REQUIREMENTS FOR DEFORMATIONS 7.1. Material furnished as Type II bar shall have deformations spaced uniformly along the length of the bar. The deformations on opposite sides of the bar shall be similar in size and shape. The average spacing or distance between deformations on both sides of
28、 the bar shall not exceed seven tenths of the nominal diameter of the bar. 7.2. The minimum height and minimum projected area of the deformations shall conform to the requirements shown in Table 3. Table 3Deformation Dimensions for Type II Bar Deformation Dimensions Nominal Diameter Maximum Average
29、Spacing Minimum Average Height Minimum Projected Areaamm in. mm in. mm in. mm2/mm in.2/in. 15 5/811.1 0.44 0.7 0.03 2.4 0.09 20 3/413.3 0.52 1.0 0.04 3.4 0.13 26 1 17.8 0.70 1.3 0.05 4.4 0.17 32 11/422.5 0.89 1.6 0.06 5.4 0.21 36 13/825.1 0.99 1.8 0.07 6.1 0.24 46 13/430.1 1.19 2.2 0.09 7.3 0.29 65
30、21/244.5 1.75 2.9 0.11 9.7 0.38 aCalculated from equation, minimum projected area = 0.75d h/s where: d = nominal diameter, h = minimum average height, and s = maximum average spacing. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is
31、a violation of applicable law.TS-4g M 275M/M 275-5 AASHTO 7.3. Mechanical CouplingFor those bars having deformations arranged in a manner to permit coupling of the bars with a screw-on type of coupler, it shall be the responsibility of the finished-bar manufacturer to demonstrate that a bar cut at a
32、ny point along its length may be coupled to any other length of bar and that a coupled joint supports the minimum specified ultimate tensile strength of the coupled bars. The coupler type shall be provided or designed by the finished-bar manufacturer. 8. MEASUREMENTS OF DEFORMATIONS 8.1. The average
33、 spacing of deformations shall be determined by dividing a measured length of the bar specimen by the number of individual deformations and fractional parts of deformations on any one side of the bar specimen. A measured length of the bar specimen shall be considered the distance from a point on a d
34、eformation to a corresponding point on any other deformation on the same side of the bar. 8.2. The average height of deformations shall be determined from measurements made on not fewer than two typical deformations. Determinations shall be based on three measurements per deformation: one at the cen
35、ter of the overall length and the other two at the quarter points of the overall length. 8.3. To indicate adequately the conformity to the dimensional requirements, measurements shall be taken at random from one bar from each 30 Mg 33 tons of each lot or fraction thereof. 8.4. Insufficient height, i
36、nsufficient projected area, or excessive spacing of deformations shall not constitute cause for rejection unless it has been clearly established by determinations on each lot that typical deformation height or spacing does not conform to the minimum requirements prescribed in Section 7. No rejection
37、 shall be made on the basis of measurements if fewer than ten adjacent deformations on each side of the bar are measured. Note 2The term “lot” shall mean all bars of the same nominal mass per linear meter weight per linear foot contained in an individual shipping release or shipping order. 9. PERMIS
38、SIBLE VARIATION IN SIZE OR MASS 9.1. For Type I bars, the permissible variation from the nominal diameter specified in Table 1 shall not exceed +0.75, 0.25 mm +0.030, 0.010 in. 9.2. For Type II bars, the permissible variation from the nominal mass specified in Table 2 shall not exceed +3 percent, 2
39、percent. 10. FINISH 10.1. The bars shall be free of defects injurious to the mechanical properties and shall have a workmanlike finish. 11. DELIVERY 11.1. Packaging and loading for shipment shall be in accordance with ASTM A700-05 (withdrawn 2014). 11.2. When specified in the contract or order, and
40、for direct procurement by or direct shipment to the U.S. Government, marking for shipment, in addition to requirements specified in the contract or 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-4g
41、M 275M/M 275-6 AASHTO order, shall be in accordance with MIL-STD-129 for military agencies and with Fed. Std. No. 123 for civil agencies. 11.3. Unless otherwise specified in the contract or order, bars shall be grouped by size. Each bundle or lift shall be tagged, showing the heat number, bar size,
42、specification number (M 275M/M 275), and the identity of the finished bar manufacturer. The tags shall display the following statement “High Strength Prestressing Bars.” Both ends of each bar shall be painted yellow. 12. INSPECTION 12.1. The inspector representing the purchaser shall have free entry
43、 at all times while work on the contract of the purchaser is being performed, to all parts of the manufacturers works that concern the manufacture of the material ordered. The manufacturer shall afford the inspector all reasonable facilities to satisfy him or her that the material is being furnished
44、 in accordance with this specification. All tests (except product analysis) and inspection shall be made at the place of manufacture prior to shipment, unless otherwise specified, and shall be so conducted as not to interfere unnecessarily with the operation of the works. 12.2. If specified in the p
45、urchase order, the purchaser shall reserve the right to perform any of the inspections set forth in the specification where such inspections are deemed necessary to assure that the material furnished conforms to prescribed requirements. 12.3. If outside inspection is waived, the finished-bar manufac
46、turers 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. 13. REJECTION 13.1. Unless otherwise specified, any rejection based on tests made in accordance with Section 5.2 shall be repor
47、ted to the manufacturer within five working days from the receipt of samples by the purchaser. 13.2. Material that shows injurious defects subsequent to its acceptance at the manufacturers works shall be subject to rejection, and the manufacturer shall be notified. 14. REHEARING 14.1. Samples tested
48、 in accordance with Section 5.2 that represent rejected material shall be preserved for two weeks from the date rejection is reported to the manufacturer. In case of dissatisfaction with the results of the tests, the manufacturer shall be permitted to make claim for a rehearing within that time. 15.
49、 CERTIFICATION 15.1. If outside inspection is waived, then a manufacturers 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-date of issue, and revision letter, if any. 15.2. The manufacturer shall, when required in the order, furnish a representative load-elongation curve for each size and type of bar shipped. 2016 by the American
