ANSI/AISC 360-22: Specification for Structural Steel Buildings – A Practical Guide for Contractors and Project Teams

ANSI/AISC 360-22 – the Specification for Structural Steel Buildings – is the current edition of the primary design standard for structural steel buildings in the United States. Published by the American Institute of Steel Construction (AISC) and approved by the American National Standards Institute (ANSI), the 2022 edition supersedes the 2016 edition and represents the current state of practice for structural steel design in the USA.

For contractors, fabricators and erectors, ANSI/AISC 360-22 is not a document to be read once and filed. It is the technical framework within which structural steel is designed, fabricated, erected, inspected and accepted. Understanding what the 2022 edition requires, what changed from the 2016 edition, and how its requirements connect to the construction methodology, the programme and the Efficient Construction Cost (ECC) is essential for every project team working with structural steel in the USA today.

This post covers what ANSI/AISC 360-22 is, what is new in the 2022 edition, what its key provisions mean for contractors and project teams, and how it connects to the construction methodology and the ECC.

What ANSI/AISC 360-22 Is

ANSI/AISC 360-22 is a consensus standard developed by AISC’s Committee on Specifications through a process that involves structural engineers, researchers, fabricators, erectors and other industry stakeholders. The ANSI designation indicates that the standard has been developed through an open, consensus-based process that meets the requirements of the American National Standards Institute.

The standard is referenced by the International Building Code (IBC) and adopted by all US states and territories as the governing standard for structural steel building design. When a building permit is issued under the IBC, the structural steel must comply with the edition of AISC 360 referenced by the applicable edition of the IBC. The 2022 edition is referenced by the 2024 IBC. Projects permitted under earlier editions of the IBC must comply with the edition of AISC 360 referenced by that IBC edition.

ANSI/AISC 360-22 covers structural steel buildings. It does not cover bridges (AASHTO), transmission towers, industrial pressure vessels or other non-building structures. For non-building structures, AISC 360 may be used as a reference but the applicable standard must be confirmed with the engineer of record.

What Is New in the 2022 Edition

The 2022 edition includes a number of significant changes from the 2016 edition. Project teams working on projects designed to ANSI/AISC 360-22 should be aware of the following key changes.

Reorganisation of Chapters

The 2022 edition reorganises several chapters to improve clarity and usability. The most significant reorganisation is the consolidation of the stability design provisions. The Direct Analysis Method, which was the primary stability analysis method in the 2016 edition, is retained and clarified. The provisions for out-of-plumbness and initial imperfections have been revised to be more consistent with the Direct Analysis Method.

Updated Material Standards

The 2022 edition updates the list of approved materials to reflect current ASTM standards. Key updates include the formal recognition of ASTM A1085 for hollow structural sections (HSS) as a preferred alternative to A500, and updated provisions for high-strength steels with yield strengths above 65 ksi. The use of A500 Grade C HSS remains permitted but A1085 is now the preferred grade for HSS due to its tighter dimensional tolerances and more consistent mechanical properties.

Revised Connection Design Provisions

Chapter J has been revised to clarify and update the connection design provisions. Key changes include updated provisions for the design of bolted connections with oversized and slotted holes, revised provisions for the block shear failure mode and updated provisions for the design of welds in combined shear and tension. The 2022 edition also includes new provisions for the design of connections using ASTM F3125 Grade F1852 and Grade F2280 twist-off bolt assemblies.

Updated Composite Construction Provisions

Chapter I has been significantly revised in the 2022 edition. The provisions for composite beams have been updated to reflect current research on the behaviour of composite beams with metal decking. Key changes include revised provisions for the strength of shear connectors in composite beams with metal decking oriented perpendicular to the beam, and new provisions for the design of composite beams with haunches. These changes affect the number of shear studs required in composite beams and therefore the fabrication and erection methodology.

New Chapter on Corrosion Protection

The 2022 edition includes a new chapter on corrosion protection that consolidates and updates the provisions for surface preparation and coating of structural steel. This chapter provides guidance on the selection of surface preparation methods and coating systems for different exposure conditions. For contractors, this chapter clarifies the surface treatment requirements that must be met before steel is delivered to site and the touch-up requirements after erection.

Revised Quality Control and Quality Assurance Provisions

Chapter N has been revised to clarify the quality control and quality assurance requirements. The 2022 edition provides more detailed guidance on the content of the fabricator’s and erector’s QC programmes and the responsibilities of the special inspector. The revised Chapter N also includes updated provisions for the inspection of high-strength bolted connections, reflecting the current RCSC Specification requirements.

Updated HSS Connection Provisions

Chapter K, which covers connections to hollow structural sections, has been significantly expanded in the 2022 edition. New provisions have been added for a wider range of HSS connection configurations, including connections with gusset plates, through-plates and reinforced connections. These changes reflect current research on HSS connection behaviour and provide more design options for engineers working with HSS structures.

Key Provisions for Contractors and Project Teams

Chapter A – General Provisions

Chapter A defines the scope of ANSI/AISC 360-22, the referenced standards and the material requirements. For contractors and project teams, the key provisions of Chapter A are the approved material standards and the mill certification requirements.

All structural steel materials must comply with the applicable ASTM standards listed in Chapter A. The use of materials that do not comply with the listed standards requires specific approval from the engineer of record. Mill certifications (mill test reports – MTRs) must be obtained for all structural steel materials and retained by the fabricator. MTRs must be made available to the special inspector and the engineer of record on request.

The approved material standards in ANSI/AISC 360-22 include:

ASTM Standard	Material	Typical Application
A36	Carbon structural steel	Plates, angles, channels – general use
A992	W-shapes	Beams and columns – standard grade
A572 Grade 50	High-strength low-alloy steel	Plates and shapes – high-strength general use
A1085	HSS (hollow structural sections)	Columns, braces, trusses – preferred HSS grade
A500 Grade C	HSS (hollow structural sections)	Columns, braces, trusses – permitted alternative
A913 Grade 65/70	W-shapes (heavy sections)	High-rise columns
A588	Weathering steel	Bridges, exposed structures
F3125 Grade A325	High-strength bolts	Standard structural bolted connections
F3125 Grade A490	High-strength bolts	High-strength bolted connections
F3125 Grade F1852	Twist-off bolt assemblies	Pretensioned bolted connections

Chapter C – Design for Stability

Chapter C covers the requirements for stability analysis and design. For contractors and erectors, the most important implication of Chapter C is that the partially erected structure must be stable at every stage of erection. The erection engineer must verify that the temporary stability of the structure during erection is adequate. This requires that the erection sequence and the temporary bracing be designed to maintain stability as each member is added to the frame.

The Direct Analysis Method, which is the primary stability analysis method in ANSI/AISC 360-22, accounts for the effects of initial imperfections and residual stresses in the stability analysis. The method requires that the analysis model include notional loads to represent the effects of initial out-of-plumbness. For erectors, this means that the erection tolerances defined in AISC 303 are not just a quality requirement – they are a structural requirement. A structure that is erected significantly out of plumb may not meet the stability requirements of Chapter C.

Chapter I – Design of Composite Members

Chapter I covers composite beams and columns. The 2022 edition includes revised provisions for shear connector strength in composite beams with metal decking. The key change is a revised equation for the strength reduction factor for shear connectors in composite beams with metal decking oriented perpendicular to the beam. The revised equation generally produces lower shear connector strengths than the 2016 edition for certain deck geometries, which may result in more shear studs being required to achieve the same degree of composite action.

For contractors and erectors, the practical implication is that the number of shear studs shown on the design drawings for projects designed to ANSI/AISC 360-22 may be higher than for equivalent projects designed to the 2016 edition. The stud welding programme must be planned accordingly.

Chapter J – Design of Connections

Chapter J covers bolted and welded connections. The key provisions for contractors and project teams are:

Bolt installation – high-strength bolts must be installed in accordance with the RCSC Specification. The installation method (snug-tight, pretensioned or slip-critical) is specified by the engineer of record on the design drawings. The contractor must verify the installation method for every bolted connection before installation begins.
Weld access holes – weld access holes must be cut to the dimensions specified in Chapter J. Undersized or incorrectly shaped weld access holes are a common fabrication deficiency that can affect the quality of the weld and the fatigue performance of the connection.
Fillet weld minimum size – the minimum fillet weld size is determined by the thickness of the thicker part joined, as specified in Table J2.4. Using a fillet weld smaller than the minimum size is a code violation regardless of whether the weld is structurally adequate for the applied loads.
CJP weld inspection – complete joint penetration welds in tension applications require ultrasonic testing (UT) or radiographic testing (RT) in accordance with AWS D1.1. The NDT must be completed and the results reviewed before the connection is loaded.

Chapter N – Quality Control and Quality Assurance

Chapter N defines the QC and QA requirements for structural steel fabrication and erection. The 2022 edition provides more detailed guidance on the content of the fabricator’s and erector’s QC programmes. Key requirements include:

Fabricator QC programme – the fabricator must have a written QC programme covering material identification, welding procedure specifications, welder qualifications, dimensional inspection and NDT. The QC programme must be submitted to the engineer of record before fabrication starts.
Erector QC programme – the erector must have a written QC programme covering bolt installation inspection, weld inspection and dimensional survey of the erected frame. The QC programme must be submitted to the engineer of record before erection starts.
Special inspection – special inspection is required for high-strength bolting, structural welding, shear connector installation and cold-formed steel deck. The special inspector must be retained by the owner and must be present at all hold points defined in the inspection programme.
Inspection programme – the engineer of record must prepare an inspection programme that identifies the inspection activities, the hold points and the acceptance criteria. The inspection programme must be included in the construction documents.

ANSI/AISC 360-22 and AISC 303-22

ANSI/AISC 360-22 is used in conjunction with AISC 303-22 – the Code of Standard Practice for Steel Buildings and Bridges. AISC 303-22 defines the standard practices and responsibilities of the owner, the engineer of record, the fabricator and the erector. It covers the shop drawing process, the mill material certification requirements, the erection tolerances and the procedures for handling errors and omissions.

The 2022 edition of AISC 303 includes several updates that are relevant to contractors and project teams:

Digital delivery of shop drawings – AISC 303-22 formally recognises the digital delivery of shop drawings and electronic approval processes. The standard now explicitly permits shop drawings to be submitted and approved electronically, reflecting current industry practice.
BIM coordination – AISC 303-22 includes new provisions addressing the use of Building Information Modelling (BIM) in structural steel construction. The standard defines the responsibilities of the fabricator and the erector in relation to BIM models and the coordination of the structural steel model with other discipline models.
Erection tolerances – the erection tolerances in AISC 303-22 are unchanged from the 2016 edition. Column plumbness tolerance remains 1/500 of the column height, with a maximum of 1 inch in the first 20 stories.

ANSI/AISC 360-22 and Seismic Design

In seismic zones, ANSI/AISC 360-22 is used in conjunction with ANSI/AISC 341-22 – the Seismic Provisions for Structural Steel Buildings. AISC 341-22 defines the additional requirements for structural steel seismic force resisting systems that apply in addition to AISC 360-22.

The 2022 editions of AISC 360 and AISC 341 were developed concurrently and are fully coordinated. Project teams working on seismic projects must comply with both standards. The seismic provisions significantly affect the fabrication and erection methodology – seismic connections require prequalified connection designs (per AISC 358-22), certified welders, rigorous weld inspection and NDT. The production rate for seismic moment frame erection is significantly lower than for standard bolted frames.

ANSI/AISC 360-22 and the Construction Programme

ANSI/AISC 360-22 affects the construction programme through its quality control, quality assurance and inspection requirements. The programme must include time for:

Fabricator QC programme submission and approval – the QC programme must be submitted and approved before fabrication starts. Allow 2–4 weeks for submission and review.
Welding procedure qualification – welding procedures must be qualified before production welding starts. Allow 2–4 weeks for procedure qualification testing.
Welder qualification – welders must be qualified before they begin production welding. Allow 1–2 days per welder for qualification testing.
Shop drawing production and approval – allow 4–8 weeks for shop drawing production and 2–4 weeks per submission for review and approval.
Special inspection hold points – hold points for bolt installation inspection, weld inspection and shear stud inspection must be included in the Level 3 programme. The special inspector must be notified in advance of each hold point.
NDT of CJP welds – allow time for UT or RT of CJP welds in tension applications. On seismic projects, NDT can be a significant programme activity.

ANSI/AISC 360-22 and the Efficient Construction Cost (ECC)

The requirements of ANSI/AISC 360-22 affect the Efficient Construction Cost (ECC) through their impact on the fabrication methodology, the erection methodology and the inspection programme. The cost of compliance must be included in the ECC. Key cost items include:

Welding procedure qualification – the cost of qualifying welding procedures before production welding starts. This is a fixed cost per project, not a per-unit cost.
Welder qualification – the cost of qualifying welders. This is a per-welder cost that must be included in the labour cost model.
NDT of welds – the cost of ultrasonic testing or radiographic testing of CJP welds. On seismic projects, NDT can add 10–20% to the welding cost.
Special inspection – the owner pays for special inspection, but the contractor must allow time for it in the programme. Delays caused by special inspection that was not programmed are the contractor’s risk.
Rework – the ECC assumes zero rework. Welds that fail inspection must be repaired and re-inspected. Rework is always more expensive than getting it right the first time. A realistic QC programme that prevents weld defects is the most cost-effective approach.
AISC Certification – maintaining AISC Certification has an annual cost that must be recovered through the overhead rate applied to structural steel work.

Transition from AISC 360-16 to AISC 360-22

Project teams transitioning from the 2016 edition to the 2022 edition should be aware of the following practical implications:

Composite beam design – the revised shear connector provisions in Chapter I may result in more shear studs being required for composite beams with perpendicular metal decking. Fabricators and erectors should verify the stud count on projects designed to the 2022 edition before pricing.
HSS material – the 2022 edition formally recognises A1085 as the preferred grade for HSS. Fabricators should confirm with their steel supplier whether A1085 is available for the required sizes and whether there is a price premium over A500 Grade C.
BIM coordination – the new BIM provisions in AISC 303-22 may impose additional coordination requirements on fabricators and erectors on projects that use BIM. The scope of BIM coordination should be clarified at bid stage.
Digital shop drawing approval – the formal recognition of digital shop drawing delivery and approval in AISC 303-22 should streamline the shop drawing process on projects that use electronic document management systems.

Common Compliance Failures Under ANSI/AISC 360-22

The most common compliance failures under ANSI/AISC 360-22 are: using steel materials that do not comply with the approved ASTM standards without EOR approval; failing to obtain and retain mill certifications for all structural steel materials; starting production welding before welding procedures are qualified and welders are qualified to those procedures; failing to notify the special inspector of hold points, resulting in work proceeding without required inspection; installing high-strength bolts using the wrong installation method or failing to achieve the required pretension; installing shear studs without a qualified stud welding procedure and without performing the required bend tests; erecting steel outside the tolerances defined in AISC 303-22 and failing to correct it before proceeding; and failing to perform NDT on CJP welds in tension applications.

Summary

ANSI/AISC 360-22 is the current edition of the primary design standard for structural steel buildings in the USA. The 2022 edition includes significant updates to the composite construction provisions, the connection design provisions, the material standards and the quality control and quality assurance requirements. For contractors, fabricators and erectors, the key principles are:

Confirm that the project is designed to ANSI/AISC 360-22 – not an earlier edition
Understand the key changes in the 2022 edition – particularly the revised composite beam provisions and the updated HSS material standards
Implement the QC programme required by Chapter N before fabrication and erection start
Qualify welding procedures and welders before production welding starts
Include special inspection hold points and NDT activities in the Level 3 programme
Obtain and retain mill certifications for all structural steel materials
Verify shear stud counts on composite beams designed to the 2022 edition before pricing
Include the cost of ANSI/AISC 360-22 compliance in the ECC – it is not optional

A project team that understands ANSI/AISC 360-22 and builds its requirements into the methodology, the programme and the estimate will deliver structural steel work that is compliant, on programme and within the ECC. One that does not will discover the cost of compliance on site – where it is always more expensive than it would have been if it had been planned for from the start.

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ANSI/AISC 360-22: Specification for Structural Steel Buildings – A Practical Guide for Contractors and Project Teams

What ANSI/AISC 360-22 Is