C channel (UPN) load capacity — span tables for single and paired channels
Channels are beams with a catch: loaded on the web plane they twist, so the tables below assume the load acts through the shear centre or the channel is restrained (bolted to a floor, boxed or paired). Values are working (unfactored) loads for S235JR, EN 1993-1-1 with a factor of about 1.4, deflection L/250. Paired channels (back-to-back, welded or bolted with spacers) carry twice the single value and do not twist.
Section properties (strong axis)
| Section | kg/m | Ix (cm⁴) | Wel,x (cm³) | Wpl,x (cm³) | ix (cm) |
|---|---|---|---|---|---|
| UPN 50 | 5.6 | 26.4 | 10.6 | 13.1 | 1.92 |
| UPN 65 | 7.1 | 57.5 | 17.7 | 21.7 | 2.52 |
| UPN 80 | 8.6 | 106 | 26.5 | 31.8 | 3.10 |
| UPN 100 | 10.6 | 206 | 41.2 | 49.0 | 3.91 |
| UPN 120 | 13.4 | 364 | 60.7 | 72.6 | 4.62 |
| UPN 140 | 16.0 | 605 | 86.4 | 103 | 5.45 |
| UPN 160 | 18.8 | 925 | 116 | 138 | 6.21 |
| UPN 180 | 22.0 | 1 350 | 150 | 179 | 6.95 |
| UPN 200 | 25.3 | 1 910 | 191 | 228 | 7.70 |
| UPN 220 | 29.4 | 2 690 | 245 | 292 | 8.48 |
| UPN 240 | 33.2 | 3 600 | 300 | 358 | 9.22 |
| UPN 260 | 37.9 | 4 820 | 371 | 442 | 9.99 |
| UPN 300 | 46.2 | 8 030 | 535 | 632 | 11.7 |
Working UDL (kN/m) — single channel, restrained, S235JR
| Section | Span 1 m | 1.5 m | 2 m | 3 m | 4 m | 5 m | 6 m |
|---|---|---|---|---|---|---|---|
| UPN 50 | 17.6 | 7.8 | 3.6 | 1.1 | — | — | — |
| UPN 65 | 29.1 | 12.9 | 7.3 | 2.3 | 1.0 | — | — |
| UPN 80 | 42.7 | 19.0 | 10.7 | 4.3 | 1.8 | — | — |
| UPN 100 | 65.8 | 29.2 | 16.4 | 7.3 | 3.5 | 1.8 | — |
| UPN 120 | 97.5 | 43.3 | 24.4 | 10.8 | 6.1 | 3.2 | 1.8 |
| UPN 140 | 138 | 61.5 | 34.6 | 15.4 | 8.7 | 5.2 | 3.0 |
| UPN 160 | 185 | 82.4 | 46.3 | 20.6 | 11.6 | 7.4 | 4.6 |
| UPN 180 | 240 | 107 | 60.1 | 26.7 | 15.0 | 9.6 | 6.7 |
| UPN 200 | 306 | 136 | 76.5 | 34.0 | 19.1 | 12.2 | 8.5 |
| UPN 220 | 392 | 174 | 98.0 | 43.6 | 24.5 | 15.7 | 10.9 |
| UPN 240 | 481 | 214 | 120 | 53.4 | 30.0 | 19.2 | 13.4 |
| UPN 260 | 593 | 264 | 148 | 65.9 | 37.1 | 23.7 | 16.5 |
| UPN 300 | 848 | 377 | 212 | 94.2 | 53.0 | 33.9 | 23.6 |
Paired (back-to-back) channels: multiply by 2. Unrestrained single channel loaded on the flange: reduce by 30–50% — check torsion. Point load at mid-span P ≈ UDL × L / 2.
Worked examples
Stair stringer: 4 m sloped length, 1.2 m wide stair, live load 3 kN/m² → 1.8 kN/m per stringer plus treads (0.5) → 2.3 kN/m → UPN 120 (6.1) is ample; UPN 140 is usual for stiffness. Lintel over a 2.5 m door in a 200 mm wall: wall load ~12 kN/m → two UPN 100 back-to-back (2 × 11) with a plate. Machine base rail: 2 m span, 20 kN machine as a point load → P ≈ UDL × L/2 → UPN 120 (24.4 × 1 = 24 kN) or UPN 140 with margin. Pipe rack cantilever: treat as cantilever — capacity ≈ quarter of the simply-supported value for the same length.
Twist and lateral restraint
A channel loaded on its flange (load not through the shear centre, which lies behind the web) twists; the tables assume restraint — deck fixed to the top flange, or channels paired, boxed or braced every 1–1.5 m. For unrestrained single channels use half the value or switch to a hollow section or IPE. Boxing two channels toe-to-toe (welded) gives a torsion-stiff member ideal for columns and posts.
Columns from channels
A single UPN is a poor column (weak axis iy 1.5–3 cm); two channels back-to-back at 50–100 mm spacing with batten plates make an efficient built-up column: 2 × UPN 100 at 3 m carry about 180 kN working, 2 × UPN 140 about 330 kN. Design the battens to EN 1993-1-1 §6.4.
Frequently asked questions
How much load can a UPN 100 carry?
About 7.3 kN/m (730 kg/m) over a 3 m span as a restrained simply supported beam in S235, 16.4 kN/m over 2 m; double for two channels back-to-back.
Which channel for a stair stringer?
UPN 120–160 for typical 3–5 m stringers, chosen for stiffness (vibration) rather than strength; UPN 140 is the common export size.
Why do channels twist under load?
The shear centre of a channel lies outside the section behind the web, so a load on the flange creates torsion. Restrain the flange, pair the channels or box them.
UPN or UPE for the same span?
UPE has similar or slightly higher capacity for the same depth at 5–10% less weight and parallel flanges; use the UPN table as a conservative guide for UPE.