FAQPage: "@type": "FAQPage" mainEntity: - "@type": "Question" "name": "What is the difference between W shapes and HSS sections in Canadian steel design?" "acceptedAnswer": "@type": "Answer" "text": "W shapes (wide flange) are open I-beam profiles optimized for flexural resistance about the strong axis — the default choice for beams and beam-columns in Canadian construction. HSS (hollow structural sections) are closed tubular profiles available in square, rectangular, and round shapes — they offer superior torsional stiffness, are preferred for columns in braced frames, and provide clean architectural lines. Per CSA S16:24, W shapes are designed per Clause 13 (flexure and axial) and HSS per Clause 13 with additional wall slenderness checks per Clause 11." - "@type": "Question" "name": "How do CISC Handbook section properties relate to CSA S16:24 design?" "acceptedAnswer": "@type": "Answer" "text": "The CISC Handbook of Steel Construction (11th Edition) provides tabulated section properties (A, I, S, r, J, Cw) that are direct inputs to CSA S16:24 design equations. For example, the elastic section modulus S is used in Clause 13.5 for flexural resistance, the radius of gyration r feeds into Clause 13.3 for column buckling, and the warping constant Cw is required for lateral-torsional buckling per Clause 13.6. All properties are calculated to ASTM A6/A6M geometric tolerances with G40.21 material certification." - "@type": "Question" "name": "What section types does CSA S16:24 cover for steel design?" "acceptedAnswer": "@type": "Answer" "text": "CSA S16:24 covers all hot-rolled structural steel sections: Class 1 (plastic design), Class 2 (compact), Class 3 (non-compact), and Class 4 (slender) per Clause 11. W shapes in 350W are typically Class 1 or 2 in flexure. HSS sections per CSA G40.21 Class C (cold-formed) or Class H (hot-formed) with wall slenderness limits per Clause 11.3. Angle sections require special consideration for single-angle bending per Clause 13.8 and bolted connection eccentricity per Clause 21." - "@type": "Question" "name": "Which Canadian steel section is most economical for typical building frames?" "acceptedAnswer": "@type": "Answer" "text": "For typical multi-storey Canadian buildings (3-12 storeys), W310 and W360 shapes in G40.21 350W are generally the most economical beam sections, providing good strength-to-weight ratios at 5-12 m spans. W250 shapes serve as columns where compact footprints matter. HSS sections gain a cost advantage in braced frames where the torsional stiffness eliminates the need for intermediate lateral bracing. The CISC Handbook provides mass-per-metre data that enables rapid cost comparison — typically, the lightest section that satisfies all CSA S16:24 limit states is the most economical."

Canadian Steel Sections Guide — W, HSS, C & L Shapes per CISC Handbook

Complete reference for structural steel sections used in Canadian construction per the CISC Handbook of Steel Construction, 11th Edition (2016). This guide covers W shapes (wide flange), HSS (hollow structural sections), C channels, and L angles — the four primary section families specified under CSA G40.21 and designed to CSA S16:24.

Quick access: CSA S16 Design Guide → | Canadian Steel Grades → | Beam Calculator → | Section Database →

Canadian Section Designation System

Canadian steel sections follow metric designations. Unlike US imperial designations (e.g. W12x26), Canadian designations state the nominal depth in millimetres and mass per metre in kg/m:

Key distinction: Canadian W shapes are physically identical to US W shapes — W310x39 is the same section as W12x26 rolled on the same ASTM A6 mill. The difference is the material certification: Canadian sections are certified to CSA G40.21 (typically 350W, Fy = 350 MPa) while US sections are certified to ASTM A992 (Fy = 345 MPa / 50 ksi). Many Canadian sections are dual-certified.

W Shapes — Wide Flange Sections

W shapes are the workhorse of Canadian structural steel construction. They provide efficient flexural resistance about the strong axis and are used for beams, girders, columns, and beam-columns.

Standard W Shape Beam Sections

The table below lists the most commonly specified W shapes in Canadian construction, sourced from CISC Handbook 11th Edition. All properties assume CSA G40.21 Grade 350W (Fy = 350 MPa).

W Shape Column Sections

W shapes with nearly equal flange width and depth for column applications:

Source: CISC Handbook of Steel Construction, 11th Edition. G40.21 350W.

Section Classification per CSA S16:24 Clause 11

CSA S16:24 classifies W shape cross-sections into four classes based on width-to-thickness ratios:

Worked Example — Classify W310x39 in 350W:

Flange: bf/2tf = 165/(2×9.2) = 8.97. Compare to 170/√350 = 9.09. Class 2 flange (compact).

Web: h/w = (310−2×9.2)/6.1 = 47.8. Compare to 1,700/√350 = 90.9. Class 1 web (plastic).

Overall classification: Class 2 (governed by flange). Use Mp for flexural resistance per Clause 13.5.

HSS — Hollow Structural Sections

HSS sections are closed tubular profiles manufactured to CSA G40.21 Class C (cold-formed, per CSA G40.20/G40.21) or Class H (hot-finished, per ASTM A501). They provide exceptional torsional rigidity and are the preferred section for columns, bracing, and architecturally exposed steel.

HSS Square Sections — Common Sizes

Source: CISC Handbook, 11th Edition. Class C = cold-formed welded, Class H = hot-formed seamless/welded.

HSS Rectangular Sections — Common Sizes

HSS Column Design per CSA S16:24

HSS columns are designed per CSA S16:24 Clause 13.3 for axial compression. The uniform radius of gyration about both axes makes HSS sections particularly efficient for columns where buckling governs:

Worked Example — HSS152x152x9.5 Axial Capacity (350W Class C):

Given: KL = 3,000 mm, Fy = 350 MPa, A = 5,310 mm², r = 58.1 mm

Slenderness parameter: λ = (KL/r) × √(Fy/π²E) = (3000/58.1) × √(350/π²×200,000) = 0.687

Compressive resistance per Clause 13.3.1:

Cr = φ × A × Fy × (1 + λ^(2×1.34))^(-1/1.34) where φ = 0.90

Cr = 0.90 × 5,310 × 350 × (1 + 0.687^(2.68))^(-1/1.34) / 1,000 = 1,190 kN

For a typical 8-storey building interior column (factored load ~800 kN), HSS152x152x9.5 provides adequate capacity with a demand-to-capacity ratio of 0.67.

HSS Wall Slenderness per Clause 11.3

For HSS in compression, the wall slenderness limit for a non-slender element is:

b/t ≤ 670/√Fy = 670/√350 = 35.8 for Class C (cold-formed)

For HSS152x152x9.5: b/t = (152−3×9.5)/9.5 = 13.0 ≤ 35.8 → OK, element is not slender.

C Shapes — Canadian Standard Channels

Canadian standard channels (C shapes) are used for purlins, girts, bracing members, and edge beams. They are designated by depth in millimetres and mass in kg/m.

Channels loaded through the shear centre are subject to warping torsion. For channel beams supporting gravity loads, provide lateral bracing at regular intervals or account for the additional warping stresses per Clause 13.6 and the CISC torsion design guide.

Channel Flexural Capacity — Worked Example

C230x22 as a simply supported purlin spanning 3,600 mm, Grade 350W:

Mf = wf × L²/8 (assume wf = 3.0 kN/m factored UDL)

Mf = 3.0 × 3.6²/8 = 4.86 kN·m

Mr = φ × Sx × Fy = 0.90 × 215 × 10³ × 350 / 10⁶ = 67.7 kN·m

D/C = 4.86/67.7 = 0.07 — well within capacity assuming lateral bracing is provided by roof deck.

L Shapes — Angle Sections

Angle sections are used for bracing, truss webs and chords, lintels, and connection components. Canadian angles are designated by leg length × leg length × thickness, all in millimetres.

Equal Leg Angles — Common Sizes

Unequal Leg Angles — Common Sizes

Angle Tension Design per CSA S16:24 Clause 13.2

Angles in tension with bolted connections require a shear lag reduction. Per Clause 12.3.3:

Worked Example — L102x102x9.5, 350W, 3-bolt connection:

Gross area Ag = 1,850 mm². Net area An = 1,850 − (9.5 × (22+2)) = 1,622 mm² (assume M20 bolts, 22 mm holes).

Effective net area per Clause 12.3.3.2(c): Ane = 0.75 × An (angles with 3 or more fasteners in line)

Ane = 0.75 × 1,622 = 1,216 mm²

Tr = φ × min(Ag×Fy, 0.85×Ane×Fu) = 0.90 × min(1,850×350, 0.85×1,216×450)/1,000

Tr = 0.90 × min(647, 465) = 419 kN

Section Selection Workflow for Canadian Designers

Step 1: Determine Governing Limit States

Per CSA S16:24, check all applicable limit states:

• Flexure: Clause 13.5 (yielding, LTB, local buckling)
• Compression: Clause 13.3 (flexural buckling, torsional-flexural buckling)
• Tension: Clause 13.2 (yielding, fracture at net section)
• Combined: Clause 13.8 (axial + flexure interaction)
• Shear: Clause 13.4 (web shear, shear buckling)
• Deflection: Appendix D (serviceability limits)

Step 2: Determine Section Class

Use Table 2 (flange limits) and Table 1 (web limits) from Clause 11. For 350W:

Step 3: Select Trial Section

Use CISC Handbook beam selection tables (Part 5) or the following rules of thumb:

• Beam span/depth ≈ 20-24 for typical floor framing
• Column r_min ≥ KL/200 for gravity columns
• HSS b/t ≤ 670/√Fy to avoid slender-element reduction

Step 4: Iterate

The lightest section satisfying all limit states is typically the most economical. However, for long-span beams, a slightly deeper section may reduce the number of pieces and connections, providing overall cost savings despite higher material weight.

Code References

• CSA S16:24 — Design of Steel Structures (Clauses 11, 12, 13, 21)
• CSA G40.20/G40.21 — General Requirements for Rolled or Welded Structural Quality Steel
• CISC Handbook of Steel Construction, 11th Edition — Section properties, design tables, and commentary
• CISC Commentary on CSA S16 — Background and explanatory notes for all clauses
• ASTM A6/A6M — General Requirements for Rolled Structural Steel Bars, Plates, Shapes, and Sheet Piling

FAQ

What is the difference between CSA G40.21 Class C and Class H HSS?

Class C HSS (CSA G40.21) are cold-formed welded hollow sections with a specified minimum yield strength of 350 MPa. Class H HSS (ASTM A501) are hot-formed seamless or welded sections with Fy = 345 MPa. Class C has slightly higher yield but undergoes cold-working residual stresses that affect column buckling behaviour (curve c per CSA S16). Class H follows buckling curve b. For column design, Class H sections may provide marginally higher capacity at intermediate slenderness. Consult CISC Table 3-4 for direct comparison.

How do I handle section class 4 (slender) elements in CSA S16?

Class 4 sections require effective width calculations per Clause 11.3. The effective width be replaces the gross width b in section property calculations, reducing the effective area Aeff, effective section modulus Seff, and member resistance. The reduction factor is k = be/b. CSA S16 Table 2 and Clause 13.5(b) provide effective width formulae based on the normalized plate slenderness λp = (b/t)/(670/√Fy). For typical W shapes in 350W, class 4 is rarely encountered — it primarily applies to thin HSS walls and plate girders.

What is the standard corrosion protection for Canadian steel sections?

CSA S16:24 Clause 29 requires corrosion protection appropriate for the exposure condition. For interior building steel, mill scale (tightly adherent) is generally acceptable per CISC guidance. For exterior exposed steel, hot-dip galvanizing to ASTM A123/A123M or CSA G164 is the standard practice. For architecturally exposed structural steel (AESS), specify CISC AESS Category 1-4 and coordinate finish requirements with the architect. In marine or industrial environments, additional paint systems (zinc-rich primer + epoxy intermediate + polyurethane topcoat) per SSPC standards are recommended.

Can I mix Canadian and US sections in the same project?

Yes, with careful attention to grade matching. A W310x39 dual-certified to CSA G40.21 350W and ASTM A992 has identical geometry. The key differences: (1) For CSA S16 design, use Fy = 350 MPa; for AISC 360 design, use Fy = 345 MPa. (2) Canadian sections carry CISC section identifiers; US sections carry AISC identifiers — verify the actual supplied dimensions. (3) Connection design per CSA S16:24 may differ from AISC 360-22 for bolt spacing, edge distances, and weld procedures. Specify governing design code in contract documents.