What is Australian PFC Channel Guide — Parallel Flange Channels per AS/NZS 3679.1 used for in structural engineering?

Australian PFC Channel Guide — Parallel Flange Channels per AS/NZS 3679.1 provides values required for steel design calculations including capacity checks, connection design, and detailing. It is referenced in structural design codes and used by practicing engineers during the design of buildings, bridges, and industrial structures.

Can I use these reference values directly in my design?

Yes, provided the values match your governing code edition and project specifications. Always cross-reference against the primary source (code document, manufacturer data, or published standard). The information on this page is for educational use — final verification by a licensed engineer is required.

How often are these reference values updated?

Reference content is maintained to align with current code editions. When a new edition of AISC 360, AS 4100, EN 1993, or CSA S16 is published, values are reviewed and updated. Check the last-modified date at the bottom of the page and verify against the current edition for your jurisdiction.

Australian PFC Channel Guide — Parallel Flange Channels per AS/NZS 3679.1

Complete engineering reference for Australian Parallel Flange Channel (PFC) sections manufactured to AS/NZS 3679.1:2016. Covers the full size range from 75PFC to 380PFC, including section properties, shear centre location, typical applications in purlins, girts, lintels, and bracing, design considerations for torsion, and worked examples per AS 4100:2020.

Related pages: AU Universal Beam Guide | AU Universal Column Guide | Cold-Formed Steel Guide | Steel Roof Purlin Design

PFC Channel Section Properties — Full Range

PFC channels use the same designation system as UB and UC sections: nominal depth (mm) followed by mass per metre (kg/m). The designation 200PFC24 indicates a parallel flange channel approximately 200 mm deep with a mass of 24.0 kg/m.

Designation	Mass (kg/m)	d (mm)	bf (mm)	tw (mm)	tf (mm)	Ix (10^6 mm^4)	Zx (10^3 mm^3)	rx (mm)	Iy (10^6 mm^4)	ry (mm)
75PFC7.1	7.1	75	40	4.0	6.1	2.91	77.6	30.9	0.29	9.8
100PFC9.9	9.9	100	50	4.0	7.5	6.27	125	41.3	0.54	12.1
125PFC13.6	13.6	125	59	4.5	8.1	11.4	183	50.8	0.97	14.8
150PFC17.7	17.7	150	68	4.8	8.8	19.1	255	60.6	1.62	17.6
180PFC21.3	21.3	180	71	5.3	9.3	29.6	329	72.1	2.33	20.2
200PFC24.0	24.0	200	75	5.6	10.0	40.3	403	79.8	3.10	22.3
230PFC27.0	27.0	230	78	6.0	11.0	56.6	492	89.9	4.12	24.1
250PFC32.2	32.2	250	85	6.5	11.0	72.6	581	97.0	4.96	25.3
300PFC37.4	37.4	300	91	6.7	12.0	119	793	114.3	7.60	28.7
380PFC46.0	46.0	380	100	7.5	13.5	221	1163	142.6	11.5	32.2

Shear Centre Location — Critical for Torsion-Free Loading

The shear centre of a PFC channel is located outside the section, behind the web. The distance from the back of the web to the shear centre (x_sc) is:

Designation	x_sc from web face (mm)	Notes
75PFC7.1	11.0	Small eccentricity
100PFC9.9	13.5
125PFC13.6	16.0
150PFC17.7	18.5
180PFC21.3	20.0
200PFC24.0	22.0	Typical purlin size
230PFC27.0	24.0
250PFC32.2	27.0
300PFC37.4	30.0
380PFC46.0	35.0	Maximum eccentricity

Typical Applications and Load Conditions

1. Roof Purlins (75PFC to 250PFC)

PFC purlins span between portal frame rafters, typically at 1.20 m, 1.50 m, or 1.80 m centres.

Typical purlin spans for 1.5 m centres:

PFC Size	Maximum Span (m)	Typical Bay Spacing
100PFC9.9	3.0	Small sheds
150PFC17.7	4.5	Light industrial
200PFC24.0	6.0	Standard portal
250PFC32.2	7.5	Wide bay portal
300PFC37.4	9.0	Heavy industrial

2. Wall Girts (100PFC to 200PFC)

Wall girts support vertical metal cladding and transfer wind loads to the main column. Girts typically span horizontally between columns at 1.5-2.5 m vertical centres.

3. Lintels (150PFC to 300PFC)

PFC lintels support brickwork or blockwork over openings. For cavity brick construction, twin PFCs bolted back-to-back with spacer tubes provide a robust lintel detail.

4. Bracing Members (75PFC to 200PFC)

PFC channels are widely used as diagonal bracing in roof and wall planes. The flat web face allows simple bolted gusset plate connections.

Comparison: PFC vs Cold-Formed C-Sections

Property	PFC (Hot-Rolled AS/NZS 3679.1)	C-Section (Cold-Formed AS/NZS 4600)
Steel grade	Grade 300 (fy = 300 MPa)	G450 or G500 (fy = 450-500 MPa)
Thickness range	4.0 - 13.5 mm	1.0 - 3.0 mm
Design standard	AS 4100	AS/NZS 4600
Residual stress	Higher (hot-rolled)	Lower (cold-formed)
Local buckling	Compact sections, no reduction	Effective width method required
Torsion resistance	Higher (solid web)	Lower (thin web distorts)
Cost per kg	Lower	10-20% higher
Typical application	Heavy secondary members	Light purlins, stud walls

Worked Example: PFC Purlin Design

Problem: Design a PFC purlin for a portal frame building with 6.5 m rafter spacing. Roof sheeting is metal deck at 0.15 kPa. Purlin spacing = 1.5 m. Roof dead load = 0.25 kPa. Roof live load = 0.25 kPa. Wind uplift = -1.2 kPa (ultimate). Use Grade 300 steel.

Step 1: Load per unit length of purlin

Dead load: w_G = 0.25 x 1.5 = 0.375 kN/m

Live load: w_Q = 0.25 x 1.5 = 0.375 kN/m

Wind uplift: w_Wu = -1.2 x 1.5 = -1.80 kN/m

Step 2: Factored load combinations

Downward: w*_down = 1.2 x 0.375 + 1.5 x 0.375 = 1.013 kN/m

Uplift: w*_up = 0.9 x 0.375 - 1.80 = -1.46 kN/m (governs)

Step 3: Maximum bending moment

M* = 1.46 x 6.5^2 / 8 = 7.71 kNm

Step 4: Required section modulus

Zx >= M* / (phi x fy) = 7.71 x 10^6 / (0.90 x 300) = 28,560 mm^3 = 28.6 x 10^3 mm^3

Step 5: Trial section

Try 150PFC17.7: Zx = 255 x 10^3 mm^3 >> 28.6 x 10^3 mm^3 — strength more than adequate.

Step 6: Check deflection under service load

w_service = 0.375 + 0.375 = 0.75 kN/m

delta = 5 x 0.75 x 6500^4 / (384 x 200,000 x 19.1 x 10^6) = 4.56 mm

Deflection limit = span/250 = 26 mm >> 4.56 mm — OK.

Result: 150PFC17.7 Grade 300 is more than adequate. Consider 125PFC13.6 for cost reduction if desired.

Frequently Asked Questions

Can PFC channels be used as columns?

PFC channels are not recommended as primary columns due to their monosymmetric cross-section and low minor-axis buckling resistance. However, they are commonly used as light posts and struts in secondary applications where the applied loads are small and buckling is restrained. If a PFC must be used in compression, design for buckling about both axes using AS 4100 Clause 6.

How do I specify PFC channels on a structural drawing?

Australian structural drawings typically specify PFC channels as: "150PFC17.7 Grade 300PLUS AS/NZS 3679.1". Include the section size, mass designation, steel grade, and the manufacturing standard. For galvanized channels, specify: "150PFC17.7 Grade 300PLUS HDG AS/NZS 3679.1".

What is the typical cost of PFC channels in Australia?

As of 2026, PFC channels in Grade 300PLUS cost approximately AUD 2,500-3,200 per tonne ex-service centre. Smaller PFCs (75-150PFC) are at the higher end due to higher processing cost per tonne. Add approximately AUD 600-800 per tonne for hot-dip galvanizing to AS/NZS 4680.

Are PFC channels available in weathering steel (Corten)?

Yes, PFC channels can be supplied in weathering steel grades equivalent to AS/NZS 3679.1 Grade WR350 (similar to ASTM A588). However, these are not standard stock items and typically require a mill rolling order with minimum tonnage (10-15 tonnes per size). Lead time for weathering steel PFCs is 8-12 weeks.

Educational reference only. All design values must be verified against the current edition of AS 4100:2020 and the project specification. This information does not constitute professional engineering advice. Always consult a qualified structural engineer for design decisions.

Disclaimer: This content is for educational purposes only. Results must be verified by a licensed professional engineer. Steel Calculator provides preliminary design tools — NOT a substitute for professional engineering judgment.