10.4.1
The following applies to the fabricator with respect to AESS:
- (a) The fabricator shall fabricate and handle the steel with care to avoid marking or distorting the steel members.
- (b) Slings shall be nylon-type or chains or wire rope with softeners.
- (c) Care shall be taken to minimize damage to any shop paint or coating.
- (d) When temporary braces or fixtures are required during fabrication or shipment, or to facilitate erection, care shall be taken to avoid blemishes or unsightly surfaces resulting from the use or removal of such temporary elements.
- (e) Tack welds not incorporated into final welds shall be treated consistently with requirements for final welds.
- (f) All weld backing and weld runoff tabs shall be removed, and the welds finished in accordance with Section 10.4.8. Removal, weld finishing, and grinding shall comply with the requirements of AWS D1.1/D1.1M, AWS D1.8/D1.8M, and ANSI/AISC 341, as applicable.
- (g) Bolted connections shall have all bolt heads on the same side of the connection and shall be consistent from one connection to another as specified by the contract documents.
Commentary
The requirements in Sections 10.4.1(f) and 10.6(f) call for the weld backing to be removed in accordance with AWS D1.1/D1.1M, and where the weld joint is part of the designated seismic force-resisting system, to also comply with ANSI/AISC 341 and AWS D1.8/D1.8M.
The requirements in Sections 10.4.1(g) and 10.6(g) do not extend to the “clocking” orientation of the bolt head (or nut).
10.4.2
Fabrication and erection marks shall not be visible for Categories AESS 2, 3, and 4, and mill marks shall not be visible for categories AESS 3 and 4. However, where members are fabricated of unfinished, reused, galvanized, or weathering steel, fabrication, erection, and mill marks may remain visible for all categories of AESS. Special requirements, if any, shall be specified as Category AESS C.
10.4.3
The permissible tolerances for member depth, width, out-of-square, and camber and sweep shall be as specified in ASTM A6/A6M and ASTM A500/A500M. The following exceptions apply:
- (a) For Categories AESS 3 and 4, spliced cross sections shall be matched to meet the acceptance criteria established with mock-up required in Section 10.1.2.
- (b) For Categories AESS 2, 3, and 4, the as-fabricated straightness tolerance shall be one-half of that specified in ASTM A6/A6M and ASTM A500/A500M.
Commentary
The ability to match individual cross sections at a member splice depends on material thickness, mill tolerances for cross-section variation, joint configuration, and the process applied to the member(s) prior to splicing, such as cambering, curving, etc. Members with thinner cross-sectional elements that vary within tolerance may be drawn together more readily than those with thicker elements, and other elements may be so thick they cannot be drawn together to match at the splice. Users are cautioned to explore fabrication costs and capabilities for joining specific member cross sections and to use a mock-up to document expectations. AISC Design Guide 33, Curved Member Design, also provides guidance on cross-section distortion for curved members.
10.4.4
For curved structural members, whether composed of a single standard structural shape or built-up, the as-fabricated variation from the theoretical curvature shall be equal to or less than the standard camber and sweep tolerances permitted for straight members in the applicable ASTM standard.
Commentary
The curvature tolerance for curved AESS members is not reduced from that used for curved non-AESS members because curved members have no straight line to sight and the resulting deviations are therefore indistinguishable. See also the Commentary to Section 11.2.2.
10.4.5
For Categories AESS 2, 3, and 4, the as-fabricated straightness tolerance for a built-up member as a whole shall be one-half of that specified in AWS D1.1/D1.1M.
10.4.6
For Categories AESS 3 and 4, copes, miters, and cuts in surfaces exposed to view shall have a gap that is uniform within 1/8 in. (3 mm), if shown to be an open joint. If instead the joint is shown to be in contact, the contact shall be uniform within 1/16 in. (2 mm).
10.4.7
For all categories of AESS, slivers and other similar discontinuities shall be removed and sharp corners resulting from shearing, flame cutting, or grinding shall be eased. For Categories AESS 1, 2, and 3, the surface condition of steel given in ASTM A6/A6M shall be acceptable. For Category AESS 4, local non-typical surface imperfections shall be filled and sanded to meet the acceptance criteria established with the mock-up required in Section 10.1.2.
10.4.8
For Categories AESS 1, 2, 3, and 4, welds shall be continuous in appearance, and weld spatter shall be removed. For Category AESS 4, welds shall be contoured and blended. Where contoured, blended, or seal welds are to be provided for Categories AESS 1, 2, and 3, those welds shall be defined in the contract documents.
Commentary
Intermittent welds are made continuous in appearance, either with additional welding, caulking, or body filler. For corrosive environments, all joints should be seal welded.
10.4.9
For Categories AESS 1 and 2, weld projection up to 1/16 in. (2 mm) is acceptable for butt and plug welded joints. For Categories AESS 3 and 4, welds shall be ground smooth/filled. In no case shall the requirements of ANSI/AISC 341 or AWS D1.8/D1.8M be violated.
10.4.10
For Categories AESS 1, 2, and 3, weld show-through shall be acceptable as produced. For Category AESS 4, the weld show-through shall meet the acceptance criteria established with the mock-up required in Section 10.1.2.
Commentary
Weld show-through is a visual indication of the presence of a weld or welds on the opposite surface from the viewer. It is a function of weld size and material thickness and can't be eliminated in thin material with thick welds. When weld show-through is a concern, this should be addressed in the mock-up.
10.4.11
AESS surfaces shall be prepared to meet the requirements of the contract documents and the specified paint or coating system (see Section 3.1).
10.4.12
For Categories AESS 1 and 2, seams of hollow structural sections shall be acceptable as produced. For Category AESS 3, seams shall be oriented as specified in the contract documents. For Category AESS 4, seams shall be ground, filled, and sanded to meet the acceptance criteria established with the mock-up required in Section 10.1.2.