AISC 360-22 – Specification for Structural Steel Buildings

Chapter A – General Provisions

This chapter outlines the overall scope, definitions, symbols, and fundamental principles governing the use of the specification. It defines the basis of design using LRFD and ASD approaches and explains the general conditions under which the specification applies.

Chapter B – Design Requirements

Chapter B presents the general requirements for structural design, including load combinations, limit states, and performance criteria. It establishes the design philosophy to ensure adequate strength, stability, and serviceability for all structural members and systems.

Chapter C – Design for Stability

This chapter covers methods to ensure global and local stability of structures. It includes the Direct Analysis Method (DAM), Notional Load Method, and Alternative Methods to account for initial imperfections, stiffness reductions, and second-order effects in structural analysis.

Chapter D – Design of Members for Tension

Design provisions for tension members are included here. It discusses the calculation of effective net area, slenderness limits, built-up tension members, and pin-connected systems. The chapter provides equations for both yielding and fracture limit states.

Chapter E – Design of Members for Compression

This section addresses compression members, such as columns and braces. It covers effective length, flexural and torsional buckling, and local buckling for slender elements. Provisions for single-angle compression members and built-up compression members are also provided.

Chapter F – Design of Members for Flexure

Flexural members (beams) are the focus of this chapter. It explains the design against yielding, lateral-torsional buckling, and local buckling for various cross-section types including I-shapes, channels, and HSS. Both compact and noncompact sections are covered in detail.

Chapter G – Design of Members for Shear

This chapter covers the shear strength of webs, panels, and other elements under shear forces. It includes provisions for tension field action, web stiffeners, and shear behavior in members with or without openings.

Chapter H – Design of Members for Combined Forces and Torsion

Members subjected to combinations of axial force, bending, shear, and torsion are designed according to this chapter. It provides equations and interaction formulas for HSS, rectangular and circular sections, and unsymmetrical members.

Chapter I – Design of Composite Members

This chapter explains the design of steel–concrete composite members, such as composite beams and columns. It discusses the transfer of forces between steel and concrete, effective stiffness, and shear connector requirements (e.g., headed studs). Design for both flexure and compression is included.

Chapter J – Design of Connections

A comprehensive section on steel connections, covering bolted, welded, and combined joints. It provides criteria for strength, geometry, spacing, and edge distances, as well as special requirements for high-strength bolts, groove welds, and fillet welds. It also covers detailing and design for block shear and bearing strength.

Chapter K – Additional Requirements for HSS and Box-Section Connections

Chapter K specifies design rules for Hollow Structural Section (HSS) and box-type member connections. It provides definitions for geometric parameters such as effective width, end distance, and chord stress interaction, ensuring adequate transfer of loads between connected elements.

Chapter L – Design for Serviceability

This chapter deals with ensuring proper performance under service loads. It addresses deflections, drift, vibration, wind-induced motion, and thermal expansion or contraction, ensuring the comfort of occupants and long-term durability of the structure.

Chapter M – Fabrication and Erection

Chapter M defines the requirements for shop fabrication and field erection of steel structures. Topics include cambering, cutting, welding, bolting, dimensional tolerances, painting, and alignment. It ensures that structures are built according to design intent and quality standards.

Chapter N – Quality Control and Quality Assurance

This chapter establishes inspection, testing, and documentation procedures to ensure quality in fabrication and erection. It defines the responsibilities of Quality Control (QC) and Quality Assurance (QA) inspectors, including non-destructive testing (NDT) of welds and bolts.

Appendix 1 – Design by Advanced Analysis

Introduces modern approaches for structural design using advanced nonlinear analysis (both geometric and material nonlinearity). These methods simulate real structural behavior more accurately compared to simplified elastic analysis.

Appendix 2 – Design of Filled Composite Members (High Strength)

Covers design procedures for concrete-filled steel tubes (CFST) and other high-strength composite members. It provides equations for axial, flexural, and combined flexural–axial strength.

Appendix 3 – Fatigue

Addresses fatigue design for structural members subjected to cyclic or fluctuating loads. It provides fatigue categories, allowable stress ranges, and special considerations for welds, bolts, and other details sensitive to fatigue failure.

Appendix 4 – Structural Design for Fire Conditions

This appendix discusses the effects of elevated temperatures on steel structures and outlines methods for fire-resistant design. It covers design by analysis, qualification testing, and performance objectives for structural integrity during fire exposure.

Appendix 5 – Evaluation of Existing Structures

Provides procedures for assessing the safety and serviceability of existing steel structures. It includes testing methods, material property evaluation, and analysis approaches to verify the remaining capacity and suitability for continued use.

Appendix 6 – Member Stability Bracing

Explains the requirements for bracing systems that prevent lateral-torsional and overall buckling of beams, columns, and beam-columns. Both point and continuous bracing systems are discussed to ensure adequate member stability.

Appendix 7 – Alternative Methods of Design for Stability

Presents simplified stability design methods such as the Effective Length Method and First-Order Analysis Method. These are alternatives to the more advanced Direct Analysis Method for specific design situations.

Appendix 8 – Approximate Analysis

This appendix provides methods for approximate second-order analysis and moment redistribution to estimate internal forces and deformations efficiently during preliminary design stages.

Commentary on the Specification

The Commentary provides in-depth explanations, background theory, and practical insights behind each provision in the specification. It helps engineers understand the intent of the code, references supporting research, and proper application of each clause. Studying the Commentary is essential for advanced structural designers seeking a deeper understanding of AISC 360.

Conclusion

The AISC 360-22 remains the cornerstone of modern steel design practice, combining advanced analytical principles with practical guidance for construction and inspection. Its comprehensive coverage of strength, stability, serviceability, and quality control makes it indispensable for engineers worldwide, ensuring safety, performance, and innovation in steel structures.