W840x391 G40.21 350W — Canadian W-Shape Section Properties

Approximate equivalent of W33X263 per AISC A6. Approx. equivalent of W33X263. Verify against CISC Handbook.

Dimensions (Metric)

Elastic Section Properties (Metric)

Torsional Properties

Imperial Reference

Section Profile Summary

With Ix = 661,806 cm⁴, this wide flange is commonly specified for long-span floor beams and transfer girders where stiffness controls the design.

At 876.3 mm deep and 391.3 kg/m, this is a heavy section for primary framing — transfer beams, long-span roof girders, and major bridge stringers.

Key Design Checks (CSA S16)

Design Notes

• Compactness: Most W-shapes in ASTM A992 satisfy the compact limits in CSA S16 Table B4.1b for flexure (λ ≤ λp). This allows full plastic moment Mp development before local buckling occurs.
• Flange local buckling (FLB): The flange slenderness ratio bf/2tf is compared against λpf = 0.38√(E/Fy) ≈ 9.0 for compact sections.
• Web local buckling (WLB): h/tw is checked against λpw = 3.76√(E/Fy) ≈ 72 for flexure, and a more restrictive limit for uniform compression.
• Lateral-torsional buckling (LTB): Lp ≈ 391.3 cm (plastic limit). For unbraced lengths ≤ Lp, the full plastic moment is available. Between Lp and Lr, linear interpolation per CSA S16 Eq. F2-2 applies.

Verification (CSA S16): All designs using this section must be verified by a licensed Professional Engineer. Before finalizing member selection, check beam-column interaction (P-M), lateral-torsional buckling, serviceability deflections, and all connection limit states. See Engineering Disclaimer.

Worked Example: Industrial floor beam — w840x391

Scenario: Light industrial floor — forklift traffic and storage considerations. Simply supported wide flange, 20.2 m span, 3 m tributary width. Service loads: 5.0 kPa dead + 7.5 kPa live (37.5 kN/m total).

Given:

• Span L = 20155 mm (20.2 m)
• Total service load w = 37.5 kN/m
• Live load portion w_L = 22.5 kN/m
• Section w840x391: Ix = 6618.1 × 10⁶ mm⁴, Sx = 15,060,000 mm³, Zx = 17,042,000 mm³
• Steel: fy = 350 MPa, E = 200,000 MPa
• Design moment resistance: φMn = 0.9 × Zx × fy = 5,368 kN·m

Step 1 — Live load deflection:

Δ_LL = 5 w_L L⁴ / (384 E Ix)

Δ_LL = 5 × 22.5 × (20155)⁴ / (384 × 200000 × 6,618,060,000)

Δ_LL = 36.5 mm

Step 2 — Deflection limit (L/250):

Δ_limit = L / 250 = 20155 / 250 = 80.6 mm

Step 3 — Dead + live deflection:

Δ_total = 60.9 mm

Step 4 — Design check:

✓ Live load deflection is within the L/250 limit.

Verify the design moment M*_Ed (from factored loads 1.35G + 1.5Q per CSA S16) does not exceed φMn = 5,368 kN·m. Also confirm shear resistance and bearing details at the supports.

Related Resources

• Steel Beam Capacity Calculator
• Column Capacity Calculator
• Beam Deflection Calculator
• Section Properties Calculator
• Steel Grades Reference
• Section Comparison Tool

Design Resources

• Section Properties Lookup — Compare with similar sections
• Steel Beam Sizes Reference — Standard beam dimensions

Educational reference only. Verify all section properties against the current CSA S16 Manual and mill certificates before design. Results are PRELIMINARY — NOT FOR CONSTRUCTION.