M2Fabrication

M2.1 Cambering, Curving, and Straightening

Local application of heat or mechanical means is permitted to be used to introduce or correct camber, curvature, and straightness. For hot-rolled structural shapes, hollow structural sections (HSS), plates, and bars conforming to the standard designations listed in Section A3.1a, the temperature of heated regions shall not exceed 1,200°F (650°C), except that for ASTM A514/A514M the temperature of heated regions shall

not exceed 1,100°F (590°C) and for ASTM A709/A709M, ASTM A913/A913M, and ASTM A1066/A1066M, the temperature shall not exceed the maximum as specified in the corresponding ASTM material standard. Subject to the approval of the engineer of record, alternative temperature limitations in accordance with recom- mendations by the producer of the material shall be used.

User Note: For other materials, as identified in Section A3.1b, limitations for the temperature of the heated regions should be consistent with the recommendations of the producer of the material.

M2.2 Thermal Cutting

Thermally cut edges shall meet the requirements of Structural Welding Code—Steel (AWS D1.1/D1.1M) clauses 7.14.5.2, 7.14.8.3, and 7.14.8.4, hereafter referred to as AWS D1.1/D1.1M, with the exception that thermally cut free edges that will not be subject to fatigue shall be free of round-bottom gouges greater than 3/16 in. (5 mm) deep and sharp V-shaped notches. Gouges deeper than 3/16 in. (5 mm) and notches shall be removed by grinding or repaired by welding.

Reentrant corners shall be formed with a curved transition. The radius need not exceed that required to fit the connection. Discontinuous corners are permitted where the material on both sides of the discontinuous reentrant corner is connected to a mating piece to prevent deformation and associated stress concentration at the corner.

User Note: Reentrant corners with a radius of 1/2 to 3/8 in. (13 to 10 mm) are generally acceptable for statically loaded work. Where pieces need to fit tightly together, a discontinuous reentrant corner is acceptable if the pieces are connected close to the corner on both sides of the discontinuous corner. Slots in HSS for gussets may be made with semicircular ends or with curved corners. Square ends are acceptable provided the edge of the gusset is welded to the HSS.

Weld access holes shall meet the geometrical requirements of Section J1.6. Beam copes and weld access holes in shapes that are to be galvanized shall be ground to bright metal. For shapes with a flange thickness not exceeding 2 in. (50 mm), the roughness of thermally cut surfaces of copes shall be no greater than a surface roughness value of 2,000 μin. (50 μm) as defined in Surface Texture, Surface Roughness, Waviness, and Lay (ASME B46.1), hereafter referred to as ASME B46.1. For beam copes and weld access holes in which the curved part of the access hole is thermally cut in ASTM A6/A6M hot-rolled shapes with a flange thickness exceeding 2 in. (50 mm) and welded built-up shapes with material thickness greater than 2 in. (50 mm), a preheat temperature of not less than 150°F (66°C) shall be applied prior to thermal cutting. The thermally cut surface of access holes in ASTM A6/A6M hot-rolled shapes with a flange thickness exceeding 2 in. (50 mm) and built-up shapes with a material thickness greater than 2 in. (50 mm) shall be ground.

User Note: The AWS Surface Roughness Guide for Oxygen Cutting (AWS C4.1-77) sample 2 may be used as a guide for evaluating the surface roughness of copes in shapes with flanges not exceeding 2 in. (50 mm) thick.

M2.3 Planing of Edges

Planing or finishing of sheared or thermally cut edges of plates or shapes is not required unless specifically called for in the construction documents or included in a stipu- lated edge preparation for welding.

M2.4 Welded Construction

Welding shall be performed in accordance with AWS D1.1/D1.1M, except as modified in Section J2.

User Note: Welder qualification tests on plate defined in AWS D1.1/D1.1M, clause 10, are appropriate for welds connecting plates, shapes, or HSS to other plates, shapes, or rectangular HSS. The 6GR tubular welder qualification is required for unbacked complete-joint-penetration groove welds of HSS T-, Y-, and K-connections.

M2.5 Bolted Construction

Parts of bolted members shall be pinned or bolted and rigidly held together during assembly. Use of a drift pin in bolt holes during assembly shall not distort the metal or enlarge the holes. Poor matching of holes shall be cause for rejection.

Bolt holes shall comply with the provisions of the RCSC Specification for Structural Joints Using High-Strength Bolts Section 3.3, hereafter referred to as the RCSC Specification. Water jet and thermally cut bolt holes are permitted and shall have a surface roughness profile not exceeding 1,000 μin. (25 μm), as defined in ASME B46.1. Gouges shall not exceed a depth of 1/16 in. (2 mm).

User Note: The AWS Surface Roughness Guide for Oxygen Cutting (AWS C4.1-77) sample 3 may be used as a guide for evaluating the surface roughness of thermally cut holes.

Fully inserted finger shims, with a total thickness of not more than ¼ in. (6 mm) within a joint, are permitted without changing the strength (based upon bolt hole type) for the design of connections. The orientation of such shims is independent of the direction of application of the load.

The use of high-strength bolts shall conform to the requirements of the RCSC Specification, except as modified in Section J3.

M2.6 Compression Joints

Compression joints that depend on contact bearing as part of the splice strength shall have the bearing surfaces of individual fabricated pieces prepared by milling, sawing, or other equivalent means.

M2.7 Dimensional Tolerances

Dimensional tolerances shall be in accordance with Section 11 of the AISC Code of Standard Practice for Steel Buildings and Bridges, hereafter referred to as the Code of Standard Practice.

M2.8 Finish of Column Bases

Column bases and base plates shall be finished in accordance with the following requirements:

• (a) Steel bearing plates 2 in. (50 mm) or less in thickness are permitted without milling provided a smooth and notch-free contact bearing surface is obtained. Steel bearing plates over 2 in. (50 mm) but not over 4 in. (100 mm) in thickness are permitted to be straightened by pressing or, if presses are not available, by milling for bearing surfaces, except as stipulated in subparagraphs (b) and (c) of this section, to obtain a smooth and notch-free contact bearing surface. Steel bearing plates over 4 in. (100 mm) in thickness shall be milled for bearing surfaces, except as stipulated in subparagraphs (b) and (c) of this section.
• (b) Bottom surfaces of bearing plates and column bases that are grouted to ensure full bearing contact on foundations need not be milled.
• (c) Top surfaces of bearing plates need not be milled when complete-joint-penetra- tion groove welds are provided between the column and the bearing plate.

M2.9 Holes for Anchor Rods

Holes for anchor rods are permitted to be mechanically or manually thermally cut, provided the quality requirements in accordance with the provisions of Section M2.2 are met.

M2.10 Drain Holes

When water can collect inside HSS or box members, either during construction or during service, the member shall be sealed, provided with a drain hole at the base, or otherwise protected from water infiltration.

M2.11 Requirements for Galvanized Members

Members and parts to be galvanized shall be designed, detailed, and fabricated to provide for flow and drainage of pickling fluids and zinc and to prevent pressure buildup in enclosed parts.

User Note: Drainage and vent holes should be detailed on fabrication documents. See the American Galvanizers Association (AGA) The Design of Products to be Hot-Dip Galvanized After Fabrication, and ASTM A123, ASTM A143/A143M, ASTM A385/A385M, ASTM F2329/F2329M, and ASTM A780/A780M for useful information on design and detailing of galvanized members. See Section M2.2 for requirements for copes of members that are to be galvanized.