ITEM 442 METAL FOR STRUCTURES

Transcription

1 ITEM 442 METAL FOR STRUCTURES Description. This Item shall govern for all structural steel, high strength bolts, forgings, steel castings, iron castings, wrought iron, bronze, steel pipe and tubing, aluminum castings and tubing, and other miscellaneous metals used in structures, except reinforcing steel and metal culvert pipe Process. All ferrous metals furnished for use under these specifications shall be made by one or more of the following processes only: Open-hearth, basic oxygen, or electric furnace. Mill test reports, supplemental test documentation and certifications required by this Item shall be furnished to the Engineer Structural Steel. (1) Steel for Bridge Structures. The material required for steel bridge structures shall be shown on the plans under the following designations: (a) Structural Steel-HYC - When shown on the plans and in the proposal as Structural Steel- HYC, the material shall conform to the requirements of ASTM A 709 Grade 250. (b) Structural Steel-HS - When shown on the plans and in the proposal as Structural Steel- HS, the material shall conform to the requirements of ASTM A 709 Grade 345 or Grade 345W. The use of either Grade 345 or Grade 345W shall be at the Contractor's discretion for painted structures, but Grade 345W must be used when weathering steel is specified. (c) Structural Steel-XHS - When shown on the plans and in the proposal as Structural Steel- XHS, the material shall conform to the requirements of ASTM A 709 Grade 485W, Grade 690, or Grade 690W. The Grade of material required shall be designated on the plans; if Grade 690 is specified, the use of either Grade 690 or Grade 690W shall be at the Contractor's discretion for painted structures, but Grade 690W must be used when weathering steel is specified. Unless otherwise shown on the plans, impact testing requirements for all grades of steel shall conform to the supplemental requirements of S83 or S84 of ASTM A 709 for tension components of a bridge member that consist of components of tension members and those portions of a flexural member that are subject to tension stress. The geographical boundaries of Zone 1 consists of all counties in Texas below a line which runs west to east below Deaf Smith and Collingsworth counties. Zone 2 shall include all counties above this line. (2) Steel for Non-Bridge Structures. Unless otherwise shown on the plans, structural steels for non-bridge structures listed herein shall conform to the longitudinal Charpy V-notch requirements of Table A for tension components of a member consisting of components of tension members and those portions of a flexural member that are subject to tension stress. Sampling and testing shall be in accordance with ASTM A 673. The (H) frequency of heat testing shall be used for all material with 250 megapascal and 345 megapascal minimum yield points. The (P) frequency of testing shall be used for all material designated as FCM's and for ASTM A 514 or A 517 steels.

2 (a) Carbon Steel. When shown on the plans and in the proposal as Structural Steel-HYC, the material shall conform to the requirements of ASTM A 36. (b) High Strength Steel (HS). High strength steel shall have a minimum required yield point of 345 megapascal, and will be shown on the plans and in the proposal as Structural Steel-HS. Structural Steel-HS shall conform to one of the following ASTM Steels subject to thickness and physical requirements of the pertinent ASTM Specification: 1. ASTM A 572, High-Strength Low-Alloy Columbium Vanadium Steels of Structural Quality With 345 Megapascal Minimum Yield Point To 100 Millimeters Thickness. Supplemental Requirement S18, for a maximum tensile strength of 655 megapascal, shall be applicable to material used for sign, signal and luminaire supports. 2. ASTM A 588, High-Strength Low-Alloy Structural Steel With 345 Megapascal Minimum Yield Point To 100 Millimeters Thickness. 3. A36MOD345, a special designation for ASTM A 36, Structural Steel modified to 345 megapascal minimum yield point and a minimum elongation of 18 percent (200 millimeters) or 21 percent (50 millimeters) and a tensile strength between 450 megapascal and 655 megapascal. Chemical requirements shall meet ASTM A 36 except that the maximum manganese content shall be 1.35 percent. Alloys containing Columbium (0.035% maximum) and Vanadium (0.06% maximum) are permissible. TABLE A LONGITUDINAL CHARPY V-NOTCH REQUIREMENTS Material Thickness Group 1 Group 2 Millimeters See Notes See Notes A 36 and A 242 Up to 100 A 572* Up to 100 mechanically fastened and Up to 50 welded A 588* Over 50 to 100 welded 27 N m 27 N m A 514 Up to 100 mechanically fastened at - 1 C at - 18 C and Up to 64 welded at - 1 C at - 18 C A 517 Over 64 to 100 welded 47 N m at - 1 C 47 N m at - 18 C

3 Notes: Group 1: Minimum Service Temperature - 18 C and above. Group 2: Minimum Service Temperature from - 18 C to - 34 C. The geographical boundaries of Group 1 consists of all counties in Texas below a line which runs West to East below Deaf Smith and Collingsworth Counties. Group 2 shall include all counties above this line. *If the yield point of the material exceeds 450 megapascal, the temperature for the CVN value for acceptability shall be reduced by 8 C for each increment of 70 megapascal or fraction thereof above 450 megapascal. (c) Extra High Strength Steel (XHS). Extra high strength steel when shown on the plans shall have a minimum required yield point of 620 megapascal and will be shown on the plans and in the proposal as Structural Steel-XHS. When so specified, the steel shall conform to the following: 1. ASTM A 514, High-Yield Strength, Quenched and Tempered Alloy Steel Plate. The steel furnished shall be suitable for welding. Structural shapes and seamless tubing, meeting the other requirements of A 514 steels, will be permitted with a maximum tensile strength of 965 megapascal for structural shapes and 1000 megapascal for seamless tubing. 2. ASTM A 517, Pressure Vessel Plates, Alloy Steel, High-Strength, Quenched and Tempered. The above listed steels are considered weldable. Other steels will require qualification in accordance with ANSI/AASHTO/AWS Bridge Welding Code D1.5 or ANSI/AWS Structural Welding Code D1.1, whichever is applicable, prior to their use. (3) Miscellaneous Steel. (a) Unless otherwise shown on the plans, structural steel for members such as shoes, diaframs, stiffeners (including bearing stiffeners), lateral bracing, diagonals, armor joints and finger joints shall conform to ASTM A 36 or A 500, Grade B. Structural steels used for secondary or nonstress-carrying members will not be subject to impact requirements. All steels greater than 12 millimeters in thickness used for structural supports for highway signs, luminaries and traffic signals shall conform to the longitudinal Charpy V-notch requirements of Group 1 in accordance with Table A. Charpy V-notch tests will not be required for pipe used in structural supports. (b) Stud shear connectors, slab anchors and anchors on armor joints and finger joints shall conform to the requirements of ASTM A 108, cold drawn bars, Grades 1010, 1015, 1018 or 1020, either semi- or fully-killed. Tensile properties as determined by tests of bar stock after drawing or finishing shall conform to the following:

4 Tensile Strength (Min.) 415 MPa Yield Strength (Min.) 345 MPa Elongation (Min.) 20% (50 mm) Reduction of Area (Min.) 50% 370. Tensile properties shall be determined in accordance with the applicable section of ASTM A The manufacturer shall certify that the studs or anchors as delivered conform with the material requirements of this section. (c) High strength bolts, nuts and washers will be sampled for tests in accordance with Test Method Tex-719-I. High strength bolts shall conform to the requirements of ASTM A 325 or A 490, unless otherwise shown on the plans. Tests, test reports and supplemental requirements for high strength bolts, nuts and washers shall be in accordance with Item 447, "Structural Bolting". When high strength bolts are not required, bolts conforming to ASTM A 307 and nuts conforming to ASTM A 563 shall be used. (d) Steel piling shall conform to the following: Type ASTM Designation Steel H Piling A 36 Sheet Piling (Rolled) A 328* Sheet Piling (Formed) A 570* Grade 36 (250 MPa, yield) *A mill certificate shall be furnished by the manufacturer certifying to the results of tests required by the governing specifications. Sheet piling of a different configuration than that shown on the plans may be used provided the section modulus and mass per meter furnished is equal to or greater than shown on the plans. (e) Deck Plates. Material for deck plates shall conform to the following: Corrosive resistant structural steel conforming to ASTM A 242. The material must be of weldable quality, and shall contain alloying elements that furnish corrosion resistance of at least twice that of copper bearing structural steel. The type of material to be used with its trade name, shall be stated on the shop drawings. (f) Rail Posts. Material for rail posts shall conform to the requirements of ASTM A 36 unless otherwise shown on the plans Steel Forgings. Steel forgings from which pins, rollers, trunnions, or other forged parts are to be fabricated, shall conform to the requirements of the Standard Specifications for Carbon-Steel Forgings for General Industrial Use, ASTM A 668, Class C, D, F or G. The above will govern for all railroad underpass structures. The class of material shall be as shown on the plans. For other structures, for pins 100 millimeters in diameter or less, material conforming to ASTM A 108, Grades 1016 to 1030 may be used. The material shall have a minimum yield point of

5 250 megapascal. All forgings shall be thoroughly annealed prior to being machined to form finished parts. Material for pins over 100 millimeters in diameter shall be in accordance with ASTM A 668, Class C, D, F or G. The class of material shall be as shown on the plans Steel Castings. Steel castings shall conform to the specifications for Mild to Medium Strength Carbon Steel Castings for General Application, ASTM A 27, Grade When shown on the plans as Class 70, Class 90, or Class 120, the steel castings shall conform to the specified class of ASTM A Iron Castings. All iron castings shall be true to pattern in form and dimensions, free from pouring faults, sponginess, cracks, blow holes, and other defects in positions affecting their strength and value for the service intended. The castings specified shall conform to one of the following ASTM Specifications. Material ASTM Grade Gray-Iron Castings A 48 Class 30 (207 MPa, tensile) Malleable Castings A Ductile Iron Castings A (tensile 414, yield 276, elongation 18 in 50 mm) Lead. Sheet lead shall conform to the requirements of the Specifications for Pig Lead, ASTM B Anchor Bolts. Unless otherwise shown on the plans, plain and threaded bars, headed bolts, medium and high strength bolts, nuts and washers shall conform to Item 449, "Anchor Bolts" Steel Pipe. Steel pipe shall conform to the material requirements shown on the plans, or in other applicable specifications Steel Tubing. Steel tubing shall conform to ASTM A 500, Grade B, unless otherwise shown on the plans or herein. Tubing conforming to API Standard 5L, Grade X52, except as noted herein, may be used if produced by a mill recognized as "authorized to produce pipe with the API monogram" and listed as such in the standard API specifications. The following exceptions to the requirements of API 5L, Grade X52, will be allowed: Hydrostatic tests will not be required. In lieu of a mill test report, a certificate from the manufacturer will be required for each lot or shipment, certifying that the tubing meets the requirements stated above Pipe Rail. Pipe shall be construed to include special extruded and bent shapes and shall be of the section shown on the plans. Pipe may be rolled or extruded to the shape shown on the plans or may be cold pressed from a round pipe or flat plate. If cold pressed, the design of the press and dies shall result in a pipe of uniform section and free from die marks. After the pipe has been formed to the required section, it shall be cut to the lengths required. The end cuts and notches shall be made at such angles with the axis of the pipe as required to produce vertical end faces and plumb posts when required by the plans. Cutting and

6 notching of pipe shall be done with a saw or machine guided torch or other means that will insure a neat and workmanlike finish Steel Deep Beam Rail. The rail element shall be either 3.43 millimeters ± 0.20 millimeters nominal thickness or 2.67 millimeters ± 0.20 millimeters nominal thickness, exclusive of protective coating, as shown on the plans. Rail element shall meet all requirements of AASHTO M- 180 except as modified on the plans. The terminal connector shall be of the same material, but shall not be less than 3.43 millimeters. Unless otherwise shown on the plans the rail element shall be galvanized in accordance with Item 445, "Galvanizing" Aluminum. (1) Unless otherwise shown on the plans, aluminum materials shall conform to the following: Castings ASTM B 108, Alloy A444-T4 Extrusions ASTM B 221, Alloy 6061-T6 Sheet & Plate ASTM B 209, Alloy 6061-T6 Test specimens from castings shall be cut from the lower 350 millimeters of the tension flange but not at the junction of the rib or base. The curved surfaces shall be flattened prior to machining. Test specimens shall conform to ASTM E 8, Figure Fabrication, Erection, and Painting. Fabrication, welding, and erection of structural metal shall be in accordance with Item 441, "Steel Structures", Item 448, "Structural Field Welding", Item 447, "Structural Bolting", and the ANSI/AASHTO/AWS Bridge Welding Code D1.5 or the ANSI/AWS Structural Welding Code D1.1, whichever is applicable. Paint and painting shall be in accordance with Item 446, "Cleaning, Paint and Painting". Aluminum or galvanized steel members shall not require painting, unless otherwise shown on the plans Galvanizing. Galvanizing of fabricated steel items, steel or iron castings, bolts, nuts, screws, washers and other miscellaneous hardware shall be in accordance with Item 445, "Galvanizing". Galvanizing will not be required for any material unless specified on the plans or in the specifications Measurement. This Item will be measured by the kilogram of structural metal furnished and placed in a complete structure, exclusive of the mass of erection bolts, paint, or weld metal. This is a plans quantity measurement Item and the quantity to be paid for will be that quantity shown in the proposal and on the "Estimate and Quantity" sheet of the contract plans, except as modified by Article 9.8. If no adjustment of quantities is required, additional measurements or calculations will not be required. The maximum percent variance from the plans quantity will be as follows:

7 Percent Variance Quantity Percent Over 450 Mg 1/2 % 45 Mg through 450 Mg 1 % Less than 45 Mg l-1/2 % When increases in size or mass of members have been made which were not ordered but were approved by the Engineer, the measurement will be made on the sizes or mass shown on the contract plans. In determining the mass of structural metal in steel or concrete structures, such items as castings, bearing plates, anchor bolts, drains, deck plates, armor joints, finger joints, and all other metal for which no separate measurement is specified will be included in the total quantity of Structural Steel. The mass of rolled shapes and plates will be computed on the basis of their nominal mass and dimensions using measurements as shown on the approved shop drawings. The mass of castings will be computed from the dimensions shown on the approved shop drawings. Shoes will be measured by the mass shown on the contract plans, or as specified for castings, if mass are not shown. Deductions will be made for all cuts, copes, perforations, and all holes except bolt holes. When computed, the mass of metal will be based on Table B. Splices will be measured as follows: (1) No additional mass will be allowed for weld metal in a welded splice. (2) Where a bolted splice is permitted as an alternate for a welded splice, measurement will be made on the basis of a welded splice. (3) Where a bolted splice is required, the mass of splice material, bolts, bolt heads, washers, and nuts, with no deduction for holes, will be measured. TABLE B Pay Mass - Kilogram per Cubic Meter Material Steel Cast Iron Wrought Iron Bronz e Lead Mass , Payment. The work performed and materials furnished in accordance with this Item and measured as provided under "Measurement" will be paid for at the unit price bid for "Structural Steel-HYC", "Structural Steel-HS", or for such other classifications of metal as shown on the plans and in the proposal. This price shall be full compensation for furnishing all materials; for all fabrication, shop work, transportation, erection, paint, painting, galvanizing; and for furnishing all equipment, tools, labor and incidentals necessary to complete the work.