Hollow section load capacity — how much weight square and rectangular tube can carry as a beam or column
The question every fabricator asks — "how much weight can a 100×100×4 tube carry?" — has two answers: as a beam (bending, deflection) and as a column (buckling). The tables below give guide values for S235JRH cold-formed hollow sections to EN 10219 designed to EN 1993-1-1 with a safety factor already applied (γM = 1.0 on resistance, loads at the ultimate limit state ≈ 1.4 × working load), plus deflection limited to L/200 for beams. They are for preliminary sizing; the project engineer confirms the final design.
Section properties used
| Section | kg/m | A (cm²) | Ix (cm⁴) | Wel,x (cm³) | Wpl,x (cm³) | ix (cm) |
|---|---|---|---|---|---|---|
| 40 × 40 × 2 | 2.31 | 2.94 | 6.9 | 3.5 | 4.1 | 1.53 |
| 40 × 40 × 3 | 3.30 | 4.21 | 9.3 | 4.7 | 5.7 | 1.49 |
| 50 × 50 × 2 | 2.93 | 3.74 | 14.1 | 5.7 | 6.6 | 1.94 |
| 50 × 50 × 3 | 4.25 | 5.41 | 19.5 | 7.8 | 9.4 | 1.90 |
| 60 × 60 × 3 | 5.19 | 6.61 | 35.1 | 11.7 | 14.0 | 2.30 |
| 70 × 70 × 3 | 6.13 | 7.81 | 57.5 | 16.4 | 19.4 | 2.71 |
| 80 × 80 × 3 | 7.07 | 9.01 | 87.8 | 22.0 | 25.8 | 3.12 |
| 80 × 80 × 4 | 9.22 | 11.7 | 111 | 27.8 | 33.1 | 3.07 |
| 100 × 100 × 3 | 8.96 | 11.4 | 177 | 35.4 | 41.1 | 3.94 |
| 100 × 100 × 4 | 11.7 | 14.9 | 226 | 45.3 | 53.3 | 3.89 |
| 100 × 100 × 5 | 14.4 | 18.4 | 271 | 54.2 | 64.6 | 3.84 |
| 120 × 120 × 4 | 14.2 | 18.1 | 402 | 67.0 | 78.0 | 4.71 |
| 120 × 120 × 5 | 17.5 | 22.4 | 485 | 80.9 | 95.4 | 4.66 |
| 150 × 150 × 5 | 22.3 | 28.4 | 982 | 131 | 153 | 5.88 |
| 150 × 150 × 6 | 26.4 | 33.6 | 1 146 | 153 | 180 | 5.84 |
| 200 × 200 × 6 | 35.8 | 45.6 | 2 833 | 283 | 329 | 7.88 |
| 200 × 200 × 8 | 46.5 | 59.2 | 3 566 | 357 | 421 | 7.76 |
| 100 × 50 × 3 (strong axis) | 6.60 | 8.41 | 105 | 21.0 | 26.1 | 3.54 |
| 120 × 60 × 4 (strong axis) | 10.5 | 13.3 | 230 | 38.4 | 47.7 | 4.15 |
| 150 × 100 × 5 (strong axis) | 18.6 | 23.7 | 739 | 98.5 | 119 | 5.58 |
| 200 × 100 × 6 (strong axis) | 26.4 | 33.6 | 1 626 | 163 | 202 | 6.96 |
Beam capacity — uniformly distributed load
Maximum working UDL in kN/m (1 kN ≈ 100 kg) for a simply supported beam, S235JRH, governed by the lower of bending (Wpl × fy / 1.4) and deflection L/200. Multiply by 1.4 for S355J2H where bending governs (short spans); deflection-governed values (long spans) do not change with grade.
| Section | Span 1.0 m | 1.5 m | 2.0 m | 3.0 m | 4.0 m | 5.0 m | 6.0 m |
|---|---|---|---|---|---|---|---|
| 40 × 40 × 2 | 5.5 | 2.4 | 1.0 | 0.3 | — | — | — |
| 50 × 50 × 3 | 12.6 | 5.6 | 2.4 | 0.7 | 0.3 | — | — |
| 60 × 60 × 3 | 18.8 | 8.3 | 4.4 | 1.3 | 0.5 | — | — |
| 80 × 80 × 3 | 34.6 | 15.4 | 8.6 | 3.3 | 1.4 | 0.7 | — |
| 80 × 80 × 4 | 44.4 | 19.7 | 11.1 | 4.1 | 1.7 | 0.9 | 0.5 |
| 100 × 100 × 4 | 71.5 | 31.8 | 17.9 | 7.9 | 3.5 | 1.8 | 1.0 |
| 100 × 100 × 5 | 86.7 | 38.5 | 21.7 | 9.6 | 4.2 | 2.2 | 1.3 |
| 120 × 120 × 5 | 128 | 56.9 | 32.0 | 14.2 | 7.5 | 3.9 | 2.2 |
| 150 × 150 × 5 | 205 | 91.3 | 51.4 | 22.8 | 12.8 | 7.9 | 4.5 |
| 150 × 150 × 6 | 241 | 107 | 60.4 | 26.8 | 15.1 | 9.2 | 5.3 |
| 200 × 200 × 6 | 441 | 196 | 110 | 49.0 | 27.6 | 17.6 | 12.2 |
| 200 × 200 × 8 | 565 | 251 | 141 | 62.8 | 35.3 | 22.6 | 15.7 |
| 100 × 50 × 3 (strong axis) | 35.0 | 15.6 | 8.8 | 3.6 | 1.6 | 0.8 | — |
| 150 × 100 × 5 (strong axis) | 160 | 71.0 | 40.0 | 17.8 | 9.6 | 5.3 | 3.4 |
| 200 × 100 × 6 (strong axis) | 271 | 120 | 67.8 | 30.1 | 16.9 | 10.8 | 7.0 |
Guide values, γ ≈ 1.4 on loads; lateral-torsional buckling negligible for hollow sections. For a point load at mid-span multiply the UDL capacity by L/2 to get the point load in kN.
Column capacity — axial compression
Working axial load in kN for a pin-ended column (effective length = height), S235JRH, EN 1993-1-1 buckling curve c (cold-formed), γ ≈ 1.4 applied. For S355J2H multiply by 1.3 (short columns) to 1.1 (slender columns).
| Section | Height 2.0 m | 2.5 m | 3.0 m | 4.0 m | 5.0 m | 6.0 m |
|---|---|---|---|---|---|---|
| 50 × 50 × 3 | 46 | 33 | 24 | 14 | 9 | — |
| 60 × 60 × 3 | 68 | 52 | 39 | 23 | 15 | 11 |
| 80 × 80 × 3 | 113 | 95 | 78 | 49 | 33 | 23 |
| 80 × 80 × 4 | 145 | 121 | 98 | 62 | 41 | 29 |
| 100 × 100 × 4 | 202 | 180 | 156 | 109 | 75 | 54 |
| 100 × 100 × 5 | 248 | 220 | 190 | 132 | 91 | 65 |
| 120 × 120 × 5 | 312 | 288 | 260 | 196 | 143 | 105 |
| 150 × 150 × 5 | 410 | 390 | 365 | 302 | 238 | 184 |
| 150 × 150 × 6 | 484 | 460 | 430 | 355 | 279 | 216 |
| 200 × 200 × 6 | 670 | 652 | 630 | 570 | 495 | 418 |
| 200 × 200 × 8 | 868 | 845 | 815 | 738 | 640 | 540 |
Fixed-base / pinned-top columns: use 0.7 × height; cantilever posts (fixed base, free top): use 2 × height.
Worked examples
Canopy beam: 4 m span, roof load 0.75 kN/m² over 2 m width = 1.5 kN/m plus self-weight → 100×100×4 (3.5 kN/m at 4 m) is adequate with margin; 80×80×4 (1.7) is marginal. Mezzanine column: 3 m high carrying 120 kN → 100×100×4 (156 kN) in S235 or 80×80×4 in S355. Gate post: 2.5 m cantilever with a 200 kg gate — treat as a bending problem (moment = weight × arm) and use at least 100×100×4 set in concrete. Racking upright: a 4 m 60×60×3 carries 23 kN axial — fine for light shelving, not for pallet racking, which needs a designed system.
What the tables do not cover
- Combined bending and compression (beam-columns): interaction per EN 1993-1-1 §6.3.3
- Concentrated loads near supports (web crippling) and torsion
- Dynamic, impact, fatigue and seismic loads
- Connections — bolted and welded joints usually govern the design
- Corrosion allowance and wall thickness below 3 mm in exposed structures
Frequently asked questions
How much weight can a 100×100×4 square tube hold?
As a simply supported beam over 3 m about 7.9 kN/m (≈ 790 kg/m, 2.4 t total) in S235; as a 3 m pin-ended column about 156 kN (≈ 15.6 t). Values include a safety factor of about 1.4.
Is a square tube stronger than an I-beam?
Per kilogram an IPE is stronger in one-direction bending; a square tube is stiffer in torsion and equally strong in both axes, so it wins as a column and for canopies loaded from any direction.
Does S355 carry more than S235?
In bending and short columns yes — about 40% more (355/235 ≈ 1.5, minus buckling effects); where deflection governs (long spans) the stiffness is the same, so no gain.
Which wall thickness should I choose?
For structures 3 mm minimum (corrosion, welding); 2 mm for fences, furniture and racks; the table shows how 4 mm raises a 100×100 beam capacity by ~25% over 3 mm.