Code Update: The 2022 AISC Specification for Structural Steel Buildings
The latest edition of the American Institute of Steel Construction (AISC) flagship standard, the “2022 Specification for Structural Steel Buildings (ANSI/AISC 360)” (the Specification), has hit the streets (get it at aisc.org/2022spec).
The 2022 edition of the Specification reflects the latest research and industry practice, coordinates with other standards, and broadens the standard’s scope—but always with users in mind and a focus on usability and transparency. The following are some of the changes you’ll find in the new standard:
Member Design Updates
Although many of the provisions for determining member strength are well established in Specification Chapters D through H, there are some notable additions and clarifications in 2022.
Section E4 includes new requirements for torsional buckling of members with lateral bracing offset from the shear center. A specific example of this limit-state, constrained-axis torsional buckling, is common (e.g., compression acting on beams restrained at the top flange by a slab).
Chapter G contains a new Section G2.3, which provides requirements to determine shear strength using tension field action in end panels of certain members with transverse stiffeners. Past editions of the Specification restricted the application of tension field action to interior web panels. Tension field action typically is relied upon for built-up members with relatively slender webs.
You’ll also find a clarification in Section F13, “Strength Reductions for Members with Bolt Holes in the Tension Flange.” This section applies specifically to bolt holes—not holes for other purposes—and the clarification reflects the conditions investigated in the underlying research.
Composite Design Updates
Specification Chapter I is significantly expanded, now including requirements for concrete-filled composite plate shear walls, commonly referred to as SpeedCore. (Visit aisc.org/speedcore for more information.) The Committee on Specifications added provisions throughout for both filled and encased members as well as a performance-based alternative for the design of shear connection that allows users to design outside the dimensional and material limits currently imposed by the Specification to align with available research.
A new Appendix 2 provides requirements for filled composite members with high-strength steel [specified minimum yield stress, Fy, exceeding 75 ksi (525 MPa) but less than 100 ksi (690MPa)] and concrete [specified compressive strength, fc’, exceeding 10 ksi (69 MPa) but less than 15 ksi (100MPa)].
Connection Design Updates
Both the AISC Specification and the Research Council on Structural Connections (RCSC) “Specification for Structural Joints Using High-Strength Bolts” apply to bolted connections, and the standards are used in tandem. High-strength bolts and bolting components should conform to the RCSC Specification when it does not contradict the AISC Specification. One big change is bolt group nomenclature. The AISC Specification now uses “Group 120,” “Group 144,” “Group 150” and “Group 200,” designations that reflect the strength of the bolting material to replace designations such as “Group A,” “Group B” and “Group C.” The 2022 edition also reflects the latest materials with the addition of “Group 144” bolts that conform to ASTM F3148.
Similarly, both the AISC Specification and American Welding Society (AWS) “Structural Welding Code—Steel (AWS D1.1/D1.1M)” define requirements for welded connections. Welding should conform to AWS D1.1/D1.1M when it does not contradict the AISC Specification. Various updates to Chapter K pertain to hollow structural section (HSS) connections, including providing a more-accurate effective width with respect to “punching” shear strength of rectangular HSS and additional requirements for addressing sidewall local yielding strength of rectangular HSS due to moment on the face. Table D3.1 also includes updated shear lag factors for HSS connected to gusset plates.
Coordination with the Code of Standard Practice
The AISC Committee on Specifications typically collaborates with the AISC Committee on the Code of Standard Practice to coordinate requirements across their respective standards. For 2022, a joint task group fielded from both committees made significant changes to the relationship between the two standards’ requirements and outlined them in Chapter A of the AISC Specification.
The biggest change is that the 2022 code now refers to the Specification for structural design document requirements. These requirements had previously appeared in Section 3 of the 2016 and earlier editions of the “AISC Code of Standard Practice for Structural Steel Buildings and Bridges.” The Specification also has a new Section A5, “Approvals,” which addresses the review and approval process of approval documents.
Complete Comparison
These are just some of the changes introduced in the 2022 Specification. A comprehensive document, “Comparison of ANSI/AISC 360-22 to ANSI/AISC 360-16,” is available at aisc.org/publications/steel-standards. The introduction to each chapter and appendix also includes a list of changes. There’s also a free, on-demand recording of the 2022 NASCC: The Steel Conference session “Overview of the 2022 Specification for Structural Steel Buildings” at learning.aisc.org.
About Nathaniel Gonner
Nathaniel Gonner, S.E., is the director of specifications for AISC; email: [email protected].
