Design of Steel Structures According to AISC 360-22

In this module, we establish the foundation of the AISC 360-22 Specification - its scope, materials, and documentation requirements. You’ll see how AISC 360 integrates with ASCE 7, AWS D1.1M, and AISC 303-22 to create a unified system for the design, fabrication, and erection of steel buildings. Understanding these relationships ensures that your designs remain consistent, code-compliant, and verifiable from concept to construction.

This module translates the specification’s design basis into day-to-day engineering steps: selecting LRFD or ASD, applying ASCE 7-22 load combinations, computing required versus available strengths for tension, compression, flexure, shear, and bearing, and documenting tolerances and QA requirements from AISC 303-22. We’ll also touch on the evaluation of existing steel structures, where verification of material properties, dimensional accuracy, and deterioration informs whether members can remain in service. By the end, you’ll have a repeatable workflow to produce code-compliant calculations and submittals.

In this Module, we focus on the fundamental requirement that every steel structure must remain stable-both globally and locally-under all load conditions. You’ll learn how AISC 360-22 Chapter C defines stability checks, how Direct Analysis Method (DAM) captures real behavior through second-order effects, imperfections, and stiffness reduction, and how simplified methods like the Effective Length Method can still be used for routine projects. By mastering these tools, you’ll ensure your structures remain safe, serviceable, and code-compliant.

In this module, our goal is to design steel members subjected to axial tension using the strength provisions of AISC 360-22 Chapter D. We’ll identify and check the two governing limit states-gross section yielding and net section rupture-then convert geometry and connection details into the correct gross, net, and effective net areas. You’ll see how LRFD and ASD are applied consistently, how bolt holes and shear lag reduce available strength, and how to extend these concepts from simple plates to angles, tees, and built-up tension members with practical, office-ready calculation notes.

In this module we move from tension to compression behavior, where instability-not material yield-usually governs strength. You’ll learn the three fundamental buckling limit states (flexural, torsional, and flexural-torsional), how slenderness and end restraint shape capacity, and how LRFD/ASD are applied to columns, struts, and compression components. We’ll also cover built-up compression members, connector spacing for shear transfer, and the treatment of slender elements via effective area. The objective is a repeatable, code-compliant workflow that converts geometry, bracing, and connection details into safe, efficient column designs.

In bending design, strength is not controlled by yield alone. Depending on unbraced length (Lb) and the compactness of the flange and web, the governing limit state can be yielding, lateral–torsional buckling (LTB), or local buckling. We will connect the geometric classification of sections (compact, non-compact, slender) to the proper AISC F-equations, introduce the moment-gradient modifier (Cb), and show how open shapes (I-shapes, channels, tees) and closed shapes (HSS/box) differ in elastic and inelastic buckling response. By the end, you will convert member geometry and bracing into LRFD/ASD-checked flexural capacity with confidence.

In steel members, webs carry most of the transverse shear, and their capacity depends on material yielding, elastic/inelastic shear buckling, and, for plate girders, post-buckling tension-field action. We’ll map member type to the correct AISC equations-compact I-shapes/channels, slender or stiffened plate girders, box/HSS walls, and round HSS-and show how web slenderness (h/tw), panel aspect ratio (a/h), and stiffeners govern the transition from shear yielding to buckling and tension-field behavior. By the end, you’ll compute Vn, apply LRFD/ASD (ϕ=1.0, Ωv=1.50), and document detailing checks that prevent crippling and excessive deformations.

Real members rarely carry a single action; they see axial load (P), bending (M) about one or both principal axes, and sometimes torsion (T) from eccentric connections or offset loading. This module shows how AISC 360 combines these effects: first ensuring separate checks Pu ≤ ϕPn, Mux ≤ ϕMnx, Muy ≤ ϕMny, Tu ≤ ϕTn, then applying interaction equations that cap the sum of demand ratios. We distinguish closed and open sections, highlight warping for open shapes, and walk through practical cases-eccentric HSS columns, open beams with torsion, and unsymmetrical sections-so you can produce clear, clause-referenced calculations.

Composite construction marries steel and concrete so both materials act together-leveraging steel’s tensile ductility and concrete’s compressive strength. This module outlines general provisions, permitted strength methods (plastic distribution, strain-compatibility, elastic, effective stress-strain), material limits, and local-buckling classification for filled sections. We’ll design composite columns (encased/filled) and composite beams with headed studs, compute effective stiffness for analysis, and apply LRFD/ASD interaction checks for P-M-T when needed. Practical detailing-stud spacing, anchor design, and stiffener/boundary elements for composite plate shear walls-rounds out a complete, submittal-ready workflow.

Under AISC 360-22 (Chapters J & M), our design aim is to transmit tension, compression, shear, and moment without overstress, slip (when prohibited), or excessive deformation. We will anchor every check in the LRFD/ASD inequalities ϕRₙ ≥ Rᵤ or Rₙ/Ω ≥ Rs, with ϕ and Ω taken from tabulated factors. Practical success demands three habits: (1) choose the right behavioral category (simple, moment, or bearing); (2) size welds/bolts/base interfaces to the controlling limit state; and (3) draw details that match assumed load paths and centroid alignment of connectors.

HSS and fabricated box members behave differently from open shapes because load spreads through closed walls, producing local wall limit states-yielding, punching (shear) of the wall, plastification, and distortion-that govern connection capacity. This module explains chord–branch parameters (β, βeff, γ = B/2t or D/2t), effective widths (Be, Bep), and the chord-stress interaction factor Qf. We’ll map the tabulated equations and limits of applicability for plate-to-HSS and HSS-to-HSS connections (T, Y, K, cross, moment), and show when rational analysis is required outside table bounds. Practical detailing-angles, end distances, and through-bolts-rounds out a constructible workflow.

Advanced analysis elevates steel design beyond member-by-member checks by solving the whole system in its deformed configuration. We explicitly include P-Δ, P-δ, torsion, connection flexibility, and geometric imperfections, and apply stiffness reductions that represent inelastic softening. Two pathways exist: elastic advanced analysis (stability + imperfections + reduced stiffness) and inelastic advanced analysis (material yielding and redistribution with ductility limits). You will see how required strengths are extracted at LRFD load levels and how available strengths still come from Chapters D-K, with column buckling satisfied inherently by the system analysis.

Fatigue concerns high-cycle, elastic stress variations that can initiate microscopic cracks and propagate them to failure at stresses well below static strength. In buildings, checks are triggered when the number of live-load cycles exceeds 20,000, and when stress ranges are significant at stress raisers-weld toes, bolt threads, reentrant corners, cope details, and attachments. We will identify when evaluation is required, how to compute stress ranges under elastic analysis, how to select detail categories A-F, and how to determine allowable stress ranges (FSR) including special rules for PJP and fillet weld roots, bolts, and threaded parts-plus fabrication/NDE requirements that unlock higher categories.

In this Module, we extend standard composite rules to rectangular filled members when either steel Fy > 525 MPa or concrete f′c > 69 MPa, up to Fy ≤ 690 MPa and f′c ≤ 100 MPa. We’ll set geometric limits, compute axial and flexural strength with slenderness-dependent Fn, and apply flexure-axial interaction using coefficients cp and cm. The central idea: the steel shell and concrete core act together, but local buckling of the steel wall and confinement of the core govern how much high-strength capacity is actually usable in design.

In This Module, Our goal is to ensure columns, beams, and beam-columns actually reach their design strengths by providing bracing with sufficient strength and stiffness against lateral translation, twist, or combined modes. We will distinguish panel, point, and continuous bracing; clarify when lateral, torsional, or combined restraint is required; and show how to size and distribute bracing demands. Keep a designer’s lens on: we are not “over-designing braces,” we are furnishing just enough restraint so member limit-state equations remain valid and reliable.

In This Module, Our aim is to preserve strength, stability, and integrity of steel and composite members during a fire’s time-temperature exposure. You’ll see how elevated temperatures reduce E and Fy, how those reductions flow into axial, flexural, and shear capacities, and how to use either Design by Analysis (thermal-structural modeling) or Design by Qualification Testing (ASTM E119 / ISO 834). We’ll also cover fire load combinations (e.g., 1.0D + 0.5L), modified resistance factors, and specific benefits of composite encasement/infilling.

By the end, you’ll produce clause-referenced, performance-ready calculations supporting the required Fire-Resistance Rating (FRR).

Appendix 7 provides simplified alternatives to the Direct Analysis Method (DAM) for verifying global and member stability when geometric nonlinear effects are limited. In this module, you’ll learn when and how to apply the Effective Length Method (ELM)-a K-factor approach based on linear elastic analysis-and the First-Order Analysis Method (FOAM)- a first-order analysis supplemented with notional lateral loads (Nᵢ) and moment amplification factors (B₁/B₂).

We’ll clearly define the scope and prerequisites and demonstrate how the bracing and stiffness requirements of Appendix 6 and Chapter C continue to govern stability verification.

By the end, you’ll be able to select the appropriate method based on structural system type, drift limits, and loading conditions.

Appendix 5 with supporting standards ASCE 59-22 and UFC 3-340-02. Extraordinary actions are short-duration, high-intensity, non-repetitive demands that can overwhelm conventional load combinations and trigger local damage, instability, or progressive collapse.

Our aims are to design ductile, redundant systems with alternate load paths, to transform dynamic actions into tractable design quantities (impulse, DLF, SDOF response), and to proportion members, connections, and details that absorb and dissipate energy. By the end, you will compute equivalent static loads, apply U = 1.0D + 0.25L + 1.0A, and check ductility/continuity to prevent disproportionate collapse.