250PFC AS/NZS 3679.1 Grade 300 — Australian Parallel Flange Channel Section Properties

250PFC is an Australian PFC (Parallel Flange Channel) per AS/NZS 3679.1 hot-rolled structural steel section. Standard Australian PFC dimensions. Verify against Liberty OneSteel / InfraBuild section catalog.

Dimensions (Metric)

Elastic Section Properties (Metric)

Torsional Properties

Section Profile Summary

The shear center of a channel lies outside the web (distance e₀ from the web face). Loads applied to the top flange produce torsion unless the load plane passes through the shear center. For AS 4100 flexural design, lateral-torsional buckling must be checked with the warping constant Cw.

At 250 mm deep, this is a mid-range section for secondary beams, roof purlins, and bracing in standard framing.

Key Design Checks (AS 4100)

Design Notes

• Section asymmetry: The shear center lies outside the web. Loads not applied through the shear center produce torsion. Provide intermediate torsional restraints or stiffeners when the load eccentricity is significant.
• Lateral-torsional buckling: Check Cb (moment modification factor) per AS 4100 Chapter F — channels are more sensitive to load height effects than doubly-symmetric sections.
• Web crippling at supports: For channels used as beams, bearing stiffeners may be needed at concentrated load points per AS 4100 Section J10.

Verification (AS 4100): 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: Hospital ward beam — 250pfc

Scenario: Hospital ward — strict deflection limits for medical equipment and services. Simply supported channel, 6.5 m span, 2.1 m tributary width. Service loads: 4.0 kPa dead + 3.0 kPa live (14.7 kN/m total).

Given:

• Span L = 6500 mm (6.5 m)
• Total service load w = 14.7 kN/m
• Live load portion w_L = 6.3 kN/m
• Section 250pfc: Ix = 34.0 × 10⁶ mm⁴, Sx = 272,000 mm³, Zx = 318,000 mm³
• Steel: fy = 300 MPa, E = 200,000 MPa
• Design moment resistance: φMn = 0.9 × Zx × fy = 86 kN·m

Step 1 — Live load deflection:

Δ_LL = 5 w_L L⁴ / (384 E Ix)

Δ_LL = 5 × 6.3 × (6500)⁴ / (384 × 200000 × 33,950,000)

Δ_LL = 21.6 mm

Step 2 — Deflection limit (L/360):

Δ_limit = L / 360 = 6500 / 360 = 18.1 mm

Step 3 — Dead + live deflection:

Δ_total = 50.3 mm

Step 4 — Design check:

⚠ Live load deflection exceeds L/360 — consider a deeper section, reduce tributary, or shorten the span.

Verify the design moment M*_Ed (from factored loads 1.35G + 1.5Q per AS 4100) does not exceed φMn = 86 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 AS 4100 Manual and mill certificates before design. Results are PRELIMINARY — NOT FOR CONSTRUCTION.