AISC -Lecture 16

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Lecture 16 – AISC Code of Standard Practice Design, fabrication, and erection of steel-framed buildings should incorporate provisions of the AISC “Code of Standard Practice for Steel Buildings and Bridges” and is found in AISC Spec. Section 16.3 and also online at www.AISC.org. It was first published in 1924 and is now in its 6th edition, dated March 7, 2005. It provides a useful framework for the understanding of the acceptable standards for the construction of structural steel structures. It is useful for owners, architects, engineers, contractors, fabricators, construction managers and anyone else involved with construction using structural steel. The Code also serves as a basis for technical project specifications, typically CSI Specification Section 05100 – Structural Steel (see Lecture 17). A summary of the Code of Standard Practice is given below. GLOSSARY

Definitions and abbreviations of relevant terms used throughout the Code. Some important, (but often vague) definitions include:

• AESS – Architecturally Exposed Structural Steel • Contract Documents • Design Drawings • EOR – Engineer-of-Record • Erection Drawings • Erector • Fabricator • Inspector • Owner • Owner’s Designated Representative for Construction • Owner’s Designated Representative for Design • RCSC – Research Council on Structural Connections • RFI – written Request for Information • SER – Structural Engineer-of-Record • Shop Drawings • Specifications • SSPC – Society for Protective Coatings (formerly Steel Structures

Painting Council) • Steel Detailer • Structural Steel

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Section 1 – GENERAL PROVISIONS

1.1 – Scope The Code shall govern the fabrication and erection of structural steel (unless otherwise noted in Contract Documents).

1.2 – Referenced Specifications, Codes and Standards

• AISC Manual of Steel Construction • AISC Seismic Provisions • AISC Specification • ASTM (lots of referenced standards) • AWS D1.1 – Structural Welding Code • RCSC Specification – Specification for Structural Joints using

ASTM A325 or A490 Bolts • SSPC – Steel Structures Painting Council

1.3 – Units

Either U.S. customary or metric units will be used. Each system shall be independent of the other.

1.4 – Design Criteria

The AISC Specification shall be used in the absence of other design criteria.

1.5 – Responsibility for Design

• If the Owner’s Designated Representative for Design provides the design, the Fabricator and Erector are NOT responsible for building code conformance of the design.

• If the Owner enters a contract with the Fabricator for

design/build, then the Fabricator IS responsible for building code conformance of the design.

1.6 – Patents and Copyrights

The EOR is responsible for obtaining patents and copyrights of design.

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1.7 – Existing Structures

Demolition, protection, field dimensions and/or abatement or removal of hazardous are NOT the responsibility of the Fabricator or Erector.

1.8 – Means, Methods and Safety of Erection

• Erector is responsible for erection of frame. • SER is responsible for structural adequacy of completed

project. Section 2 – CLASSIFICATION OF MATERIALS

Structural Steel shall consist of the following typical elements:

• Anchor Rods that will receive structural steel • Base Plates & bearing plates • Beams • Bracing (permanent) • Columns • Connections • Fasteners for connecting structural steel • Girders • Hangers • Lintels • Shear stud connectors • Trusses

Section 3 – DESIGN DRAWINGS AND SPECIFICATIONS

3.1 – Structural Design Drawings and Specifications

Structural design drawings shall consider design loads and forces in the completed project.

Drawings must show:

• Size, section, location and material grade of all members • Geometry and working points necessary for layout • Floor elevations • Column centers and offsets • Camber requirements for beams (if required) • Permanent bracing, stiffeners, reinforcement • Connection details or data that can be used by fabricator for

design including ASD or LRFD methodology • Data relating to non-Structural steel elements that interact

with frame • Painting requirements of Structural steel

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3.2 – Architectural, Electrical and Mechanical Design Drawings

Other trades’ design drawings may be used to show structural steel elements for purposes of defining detail configurations and other construction information, however, ALL STRUCTURAL INFO. MUST BE SHOWN ON STRUCTURAL DRAWINGS.

3.3 – Discrepancies

• Discrepancies discovered in the Contract Documents shall be resolved by the EOR in a timely manner so as not to delay the Fabricator’s work.

Discrepancies between: Which Governs:

Design Drawings Specifications Design Drawings Scaled graphic drawings Written info in drawing Written info in drawings Arch., Elect., Mech. Drawings

Structural Drawings Structural Drawings

3.4 – Legibility of Design Drawings

Design Drawings must be legible and drawn to a scale of not smaller than 1/8” = 1’-0” (unless clarity of the drawing is carefully considered), larger as necessary to convey detailed information.

3.5 – Revisions to Design Drawings and Specifications

All revisions must be communicated either by issuing new Design Drawings and Specifications or by re-issuing existing Design Drawings and Specifications. Revisions must be clearly and individually indicated, dated and identified by a revision number. These revised sketches become “amendments” to the Contract Drawings.

3.6 – Fast-Track Project Delivery

Release of structural Design Drawings and Specifications shall constitute a release for construction, regardless of the status of the architectural, electrical, mechanical, or any other trades’ documents.

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Section 4 – SHOP AND ERECTION DRAWINGS

4.1 – Owner Responsibility

The Owner shall furnish the complete structural Design Drawings and Specifications to the Fabricator in a TIMELY MANNER.

4.2 – Fabricator Responsibility

Fabricator shall produce Shop Drawings and Erection Drawings. Fabricators are permitted to use the services of independent detailers.

4.3 – Use of CAD and/or Copies of Design Drawings

Fabricator shall NOT reproduce any part of the Design Drawings as part of the Shop or Erection Drawings without the express written permission of Owner’s Designated Representative for Design.

4.4 – Approval

Shop and Erection Drawings must be submitted to Owner’s Representative for Design for review and approval and returned to Fabricator within 14 calendar days.

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Section 5 – MATERIALS

5.1 – Mill Materials

Fabricator is permitted to order materials upon receipt of Contract Documents that have been issued for construction. If mill materials do not meet ASTM A6 tolerances, Fabricator is permitted to make corrective procedures.

5.2 – Stock Materials

Fabricator may use stock materials if they meet with required ASTM specifications. Certified mill test reports are used as evidence of record of quality of material.

Section 6 – SHOP FABRICATION AND DELIVERY

6.1 – Identification of Material

Materials used for special requirements shall be marked by the supplier as specified by ASTM A6 prior to delivery to Fabricator’s shop or point of use.

6.2 – Preparation of Material

Thermal cutting of material is permitted. Surfaced specified as “finished” shall have a roughness in accordance with ANSI/ASME B46.1 that is less than or equal to 500.

6.3 – Fitting and Fastening

Projecting elements of connection materials need not be straightened in the connecting plane. Backing bars and runoff tabs shall be used to produce as required to produce sound welds, and do not need be removed unless specifically designated in the Contract Documents.

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6.4 – Fabrication Tolerances

The following tolerances are to be used:

Member Type: Tolerance Variation: Both ends finished for contact bearing Length = ± 1/32” Members < 30’-0” Length = ± 1/16” Members > 30’-0” Length = ± 1/8” All members Straightness < 1/1000 axial length Beam length < 50’-0” Camber variation = 0 → ½” Beam length > 50’-0” Camber variation = 0 → ½” + 1/8” per

10’-0” additional length beyond 50’-0”

6.5 – Shop Cleaning and Painting

Structural steel that does not require shop paint shall be cleaned of oil, grease, dirt and any foreign material. Structural steel requiring shop painting shall be free of oil, grease, dirt and any foreign material; as well as meeting the requirements of SSPC-SP2.

6.6 – Marking and Shipping of Materials

Erection marks shall be painted to all structural steel members. Connection members shall be shipped in separate closed containers according to grade, length and diameter.

6.7 – Delivery of Materials

Steel shall be delivered in a sequence that will permit efficient and economical fabrication and erection.

Section 7 – ERECTION

7.1 – Method of Erection

Structural steel shall be erected using methods and a sequence that will permit efficiency and economy.

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7.2 – Job-Site Conditions

Owner’s Representative for Construction shall provide the following:

• Access road for deliveries and movement of materials • Adequate obstruction-free space for operation of Erector’s

equipment • Adequate storage space

7.3 – Foundations, Piers and Abutments

Owner’s Representative for Construction shall be responsible for accurate location, suitability and access to all foundations, piers and abutments.

7.4 – Building Lines and Bench Marks

Owner’s Representative for Construction shall be responsible for accurate location of building lines and benchmarks and shall furnish the Fabricator with a plan containing such information.

7.5 – Installation of Anchor Rods and Other Embedded Items

Owner’s Representative for Construction shall be responsible for setting in accordance with Embedment Drawings. The variation in location shall be as follows:

Item: Variation in Dimension: Centers of any 2 anchor rods within an anchor rod group

< 1/8”

Centers of adjacent anchor rod groups < ¼” Elevation of tops of anchor rods ± ½” Accumulated variation between centers of anchor rod groups

< ¼” per 100’-0” not to exceed a total of 1”

7.6 – Installation of Bearing Devices

All leveling plates, nuts, washers and bearing plates that can be handled without crane are set to line and grade by the Owner’s Representative for Construction (otherwise set by Erector).

7.7 – Grouting

Grouting shall be the responsibility of the Owner’s Representative for Construction. The usual method for supporting columns during erection is by use of leveling nuts and washers or shims.

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7.8 – Field Connection Material

Fabricator shall provide field connection details consistent with Contract Documents.

7.9 – Loose Material

Unless otherwise noted, loose structural steel items that are not connected to the steel frame by the Owner’s Representative for Construction without assistance from Fabricator.

7.10 – Temporary Support of Structural Steel Frames

The Owner’s Designated Representative for Design shall identify the following:

• Lateral load resisting system and connecting diaphragm elements providing stability in the completed structure

• Any special erection conditions that are required by the design concept, such as use of jacks, shores, etc.

7.11 – Safety Protection

The Erector shall provide floor coverings, handrails, walkways and other protection for the Erector’s personnel in accordance with all applicable safety regulations. Unless otherwise specified, the Erector is permitted to remove such safety protection form areas where the erection operations are completed. Safety protection for other trades that are not under the direct employment of the Erector shall be the responsibility of the Owner’s Representative for Construction.

7.12 – Structural Steel Frame Tolerances

The accumulation of the mill tolerances (Section 6.4) and fabrication tolerances shall not cause the erection tolerances (Section 7-13) to be exceeded.

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7.13 – Erection Tolerances

Erection tolerances are referenced from Work Points and Work Lines defined as:

• Members other than horizontal members, the member work point is the actual center of the member at each end of the shipping piece.

• Horizontal members work point shall be the actual centerline of the top flange or top surface at each end.

• Work line is defined a s a straight line that connects the member work points.

Member: Erection Tolerance:

Column tolerance deviation from plumb ± 1/500 distance between work points not to exceed 1” total for first 20 stories

Individual straight piece (other than column) connecting to column

+ 3/16” - 5/16”

Adjustable members ± 3/8”

7.14 – Correction of Errors

Correction of minor misfits by means of reaming, grinding, drawing of elements into line by drift pins, welding or cutting shall be considered normal erection operations. Errors that cannot be corrected by these means must be promptly reported to the Owner’s Designated Representative for Design and Construction.

7.15 – Cuts, Alterations and Holes for Other Trades

The Fabricator or the Erector may NOT cut, drill or otherwise alter their work to accommodate other trades unless work is specified in the Contract Documents.

7.16 – Handling and Storage

The Erector shall take reasonable care in the proper handling and storage of structural steel during erection to avoid excess dirt and foreign matter. However, it is not the Erector’s responsibility to remove dirt or other foreign material that may accumulate during normal erection procedures.

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7.17 – Field Painting

The Fabricator or the Erector is NOT responsible to paint field bolts, or to touch-up abrasions of the shop coat, or to perform any field painting.

7.18 – Final Cleaning Up

Upon completion and acceptance, the Erector shall remove any of the Erector’s falsework, scaffolding, rubbish and temporary structures.

Section 8 – QUALITY ASSURANCE

8.1 – General The Fabricator shall maintain a quality assurance program to assure that the work is performed in accordance with this Code.

8.2 – Inspection of Mill Material

Certified mill test reports shall constitute sufficient evidence that the mill product satisfies material order requirements.

8.3 – Non-Destructive Testing

As per Contract Documents.

8.4 – Surface Preparation and Shop Painting Inspection

As per Contract Documents.

8.5 – Independent Inspection

• Fabricator and Erector shall provide the Inspector with access to all places where work is being performed, and a minimum of 24 hours notice must be given prior to commencement of work.

• Inspector shall inspect work at shop as much as possible. • Field inspections should be performed as promptly as

possible. • Deficiencies discovered by Inspector shall be reported to

Fabricator and Erector as soon as possible. • The Inspector shall NOT approve of any deviations from the

Contract Documents without written approval from the Owner’s Designated Representative for Design and Construction.

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Section 9 – CONTRACTS

9.1 – Types of Contracts

• Lump sum price • Price per pound • Price per item • Unit price

9.2 – Calculation of Weights

Weight is determined by calculation of gross weight of materials as shown on the Shop Drawings. This does NOT include shop and field weld metal or protective coatings. Deductions shall not be made for holes, copes, drilling or other removals for connections. Steel unit weight = 490 lb/ft3.

9.3 – Revisions to Contract Documents

Revisions to Contract Drawings shall be confirmed by change order or extra work order, and shall constitute authorization by the Owner that the revision is released for construction.

9.4 – Contract Price Adjustment

When the scope of work and responsibilities of the Fabricator and the Erector are changed, an appropriate modification to the contract price shall be made. Requests for contract price adjustments shall be presented to the Owner and approved/disapproved in a timely manner.

9.5 – Scheduling

The contract schedule shall state when the Design Drawings will be released for construction so that erection can start at the designated time and continue without interference or delay.

9.6 – Terms of Payment

Terms of payment shall be outlined in the Contract Documents.

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Section 10 – ARCHITECTURALLY EXPOSED STRUCTURAL STEEL

The rapidly increasing use of exposed structural steel as an aesthetic design medium has prompted the use of additional requirements that apply to these members. Typically they call for closer dimensional tolerances and smoother finished surfaces than for ordinary structural steel. 10.1 – General Requirements

When members are specifically designated in the Design Drawings as “Architecturally Exposed Structural Steel”, the requirements in Sections 1 through 9 shall apply as modified in Section 10.

10.2 – Fabrication

Permissible tolerances shall conform to ASTM A6.

• All copes, miters and cuts in surfaces exposed to view shall be made with uniform gaps of 1/8”.

• All welds exposed to view shall not project more than 1/16”

above the surface.

• Seams of hollow structural sections (HSS) shall be oriented away from view.

10.3 – Delivery of Materials

Fabricator shall take extra care and precautions to avoid bending, twisting or otherwise damaging the structural steel.

10.4 – Erection

Erector shall take extra care and precautions to minimize damage during handling and erection procedures. Unless otherwise noted, AESS members shall be plumbed, leveled and aligned to a tolerance that is ½ that of non-AESS members.

AISC -Lecture 16

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