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Building Design and Construction Handbook - Merritt - Ventech!

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7.4 FABRICATION<br />

STRUCTURAL STEEL CONSTRUCTION 7.17<br />

When considering fabrication, as well as erection of the fabricated product, the<br />

designer must taken into account contractual matters, work by others on the construction<br />

team, schedule implications of the design, <strong>and</strong> quality assurance matters.<br />

Fortunately, there are well established aids for these considerations. Contractual<br />

questions such as what constitutes structural steel, procedures for preparing <strong>and</strong><br />

approving the shop detail drawings, <strong>and</strong> st<strong>and</strong>ard fabrication procedures <strong>and</strong> tolerances<br />

are all addressed in the AISC’s Code of St<strong>and</strong>ard Practice (Table 7.1).<br />

Insights on economical connection details <strong>and</strong> the impact of material selection on<br />

mill material deliveries are generally available from the fabricator’s engineering<br />

staff. These engineers are also able to comment on unique erection questions.<br />

Quality assurance questions fall into two categories, fabrication operations <strong>and</strong><br />

field operations. Today, sound quality control procedures are in place in most fabrication<br />

shops through an AISC program which prequalifies fabricators. There are<br />

three levels of qualification: I, II <strong>and</strong> III, with Level III being the most dem<strong>and</strong>ing.<br />

Fabricators with either a Level I or Level II certification are suitable for almost all<br />

building work.<br />

Most engineers incorporate the AISC’s Code of St<strong>and</strong>ard Practice in their project<br />

specification.<br />

7.4.1 Shop Detail Drawings<br />

Detail drawings are prepared by the fabricator to delineate to his work force the<br />

fabrication requirements. Because each shop has certain differences in equipment<br />

<strong>and</strong>/or procedures, the fabricator develops details which, when matched with his<br />

processes, are the most economical. To accomplish this end, the design drawings<br />

need to be complete, showing all structural steel requirements, <strong>and</strong> should include<br />

design information on the forces acting at connections. <strong>Design</strong>ers should avoid<br />

specifying deck openings <strong>and</strong> beam penetrations through notes on the drawings.<br />

This is a frequent cause of extra costs on fabrication contracts.<br />

7.4.2 Fabrication Processes<br />

Mill material is cut to length by sawing, shearing, or flame cutting. Columns may<br />

also be milled to their final length. Holes for fasteners are drilled or punched.<br />

Punched <strong>and</strong> reamed holes are seldom used in building construction. Cuts for weld<br />

preparation, web openings, <strong>and</strong> dimensional clearances are flame cut. AISC guidelines<br />

for each of these processes are associated with the AISC’s fabricator prequalification<br />

program. Welding for building construction is performed in accordance<br />

with the provisions of the AWS Structural Welding Code, D1.1. Most requirements<br />

can be satisfied using pre-qualified welding procedures.<br />

7.5 QUALITY ASSURANCE<br />

Concepts for improving <strong>and</strong> maintaining quality in the constructed project stress<br />

the participation of the design professional in the project team consisting of the

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