Tubular column TC1
CHS 219.1 × 6 · YSt 310 · L = 4.5 m · P = 902.1 kN · IS 800:2007
All checks OK
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1. Design summary
All design checks are satisfied. Maximum utilisation 0.95.
| Project | - |
|---|---|
| Client / location | - |
| Member | C1 - Tubular column TC1 |
| Member type | Circular hollow section (CHS) |
| Section | CHS 219.1 × 6 |
| Steel | YSt 310: fy = 310 N/mm², fu = 450 N/mm² |
| Length | 4.500 m |
| Design axial force | 902.1 kN (Factored design load (input)) |
| Design compressive strength | Pd = 947.6 kN (buckling about z-z) |
| Self weight of member | 31.5 kg/m - 142 kg |
| Report date | 31 Oct 2026 |
Summary of design checks
| Check | Clause | Demand | Capacity | Ratio | Status |
|---|---|---|---|---|---|
| Slenderness ratio KL/r | Table 3 | 47.78 | 180.00 | 0.265 | OK |
| Axial compression (buckling about z-z) | 7.1.2 | 902.09 kN | 947.57 kN | 0.952 | OK |
| Bearing pressure on concrete | 7.4.1 | 7.80 N/mm² | 15.00 N/mm² | 0.520 | OK |
| Base plate thickness | 7.4.3.1 | 14.82 mm | 16.00 mm | 0.926 | OK |
2. Design basis and material
- IS 800:2007 General construction in steel - Code of practice (limit state method).
- IS 808:1989 Dimensions for hot rolled steel beam, column, channel and angle sections.
- IS 2062:2011 Hot rolled structural steel; IS 4923:2017 Hollow steel sections.
- IS 875 (Parts 1-3) and IS 1893 for loads; IS 456:2000 for the concrete pedestal.
- Section properties are computed from the IS 808 outline (tapered flanges and root fillets of rolled shapes included); they agree with the tabulated values within about 1-3 %.
| γm0 - resistance governed by yielding | 1.10 (Table 5) |
|---|---|
| γm1 - resistance governed by ultimate stress | 1.25 (Table 5) |
| γmb - bolts (bearing type) | 1.25 (Table 5) |
| γmw - shop welds | 1.25 (Table 5) |
| Modulus of elasticity E | 200,000 N/mm² (2.2.4.1) |
| Shear modulus G | 76,900 N/mm² (2.2.4.1) |
Material strength (IS 800 Table 1 / IS 2062)OK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| Table 1 | Steel grade | YSt 310 | ||
| Governing thickness | maximum element thickness t = 6 mm (t < 20 mm) | |||
| Table 1 | Yield stress fy | fy for t < 20 mm | 310 N/mm² | |
| Table 1 | Ultimate stress fu | 450 N/mm² | ||
| Table 2 | ε | √(250 / fy) = √(250 / 310) | 0.898 | |
| 5.4.1 | Design yield stress | fy / γm0 = 310 / 1.1 | 281.8 N/mm² |
3. Section properties
| Area A | 4,014 mm² |
|---|---|
| Mass | 31.51 kg/m |
| Iz (major axis) | 2,278.7 cm⁴ |
| Iy (minor axis) | 2,278.7 cm⁴ |
| rz | 75.3 mm |
| ry | 75.3 mm |
| Zez / Zey (elastic) | 208.0 / 208.0 cm³ |
| Zpz / Zpy (plastic) | 272.2 / 272.2 cm³ |
| Torsion constant It | 4,560.28 cm⁴ |
4. Design loads
Design forcesOK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| Factored axial force | Factored design load (input) | 900.0 kN | ||
| Table 4 | Factored self weight | 1.5 × 31.51 kg/m × 9.81 × 4.500 m | 2.09 kN | |
| Design axial force P | applied + self weight (at the base, conservatively over the full length) | 902.1 kN |
5. Section classification
Compression elements are classified to IS 800 Table 2. Limits are shown as plastic / compact / semi-compact (multiples of ε, or ε² for tubes, already applied). An element beyond the semi-compact limit is slender and only its effective width is counted (Cl. 7.3.2).
Section classification (Table 2)
| Element | Table 2 row | b / t (mm) | Ratio | Limits | Class |
|---|---|---|---|---|---|
| Tube wall | Circular hollow tube | 219.1 / 6.0 | 36.52 | - / - / 71.0 | Semi-compact |
Classification resultOK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| 3.7.2 | Section class | governed by the most slender element | Semi-compact | |
| 7.3.2 | Effective area | no slender element: Ae = A | Ae = 4,014 mm² |
6. Effective length and slenderness
Effective length and slenderness about z-zOK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| Table 11 | End restraint | Fixed at one end, pinned at the other | K = 0.8 | |
| 7.2.2 | Unbraced length | L | 4,500 mm | |
| 7.2.2 | Effective length KL | 0.8 × 4,500 | 3,600 mm | |
| Radius of gyration rz | 75.3 mm | |||
| 7.1.2 | Slenderness KL/r | 3,600 / 75.3 | 47.8 | |
| Table 3 | Slenderness limit | 47.8 ≤ 180 - Member carrying compressive loads from dead and imposed loads | OK | OK |
Effective length and slenderness about y-yOK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| Table 11 | End restraint | Fixed at one end, pinned at the other | K = 0.8 | |
| 7.2.2 | Unbraced length | L | 4,500 mm | |
| 7.2.2 | Effective length KL | 0.8 × 4,500 | 3,600 mm | |
| Radius of gyration ry | 75.3 mm | |||
| 7.1.2 | Slenderness KL/r | 3,600 / 75.3 | 47.8 | |
| Table 3 | Slenderness limit | 47.8 ≤ 180 - Member carrying compressive loads from dead and imposed loads | OK | OK |
7. Design compressive strength
Buckling about z-zOK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| Table 10 | Buckling class | cold formed hollow section | b | |
| Table 7 | Imperfection factor α | 0.34 | ||
| 7.1.2.1 | Euler buckling stress fcc | π² E / (KL/r)² = π² × 200,000 / 47.8² | 864.6 N/mm² | |
| 7.1.2.1 | Non-dimensional slenderness λ | √(fy / fcc) = √(310 / 864.6) | 0.599 | |
| 7.1.2.1 | φ | 0.5 [1 + α (λ − 0.2) + λ²] = 0.5 [1 + 0.34 (0.599 − 0.2) + 0.599²] | 0.747 | |
| 7.1.2.1 | Stress reduction factor χ | 1 / [φ + √(φ² − λ²)] | 0.838 | |
| 7.1.2.1 | Design compressive stress fcd | χ fy / γm0 = 0.838 × 310 / 1.1 (≤ fy/γm0) | 236.1 N/mm² | |
| 7.1.2 | Design compressive strength Pd | Ae fcd = 4,014 × 236.1 / 1000 | 947.6 kN |
Buckling about y-yOK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| Table 10 | Buckling class | cold formed hollow section | b | |
| Table 7 | Imperfection factor α | 0.34 | ||
| 7.1.2.1 | Euler buckling stress fcc | π² E / (KL/r)² = π² × 200,000 / 47.8² | 864.6 N/mm² | |
| 7.1.2.1 | Non-dimensional slenderness λ | √(fy / fcc) = √(310 / 864.6) | 0.599 | |
| 7.1.2.1 | φ | 0.5 [1 + α (λ − 0.2) + λ²] = 0.5 [1 + 0.34 (0.599 − 0.2) + 0.599²] | 0.747 | |
| 7.1.2.1 | Stress reduction factor χ | 1 / [φ + √(φ² − λ²)] | 0.838 | |
| 7.1.2.1 | Design compressive stress fcd | χ fy / γm0 = 0.838 × 310 / 1.1 (≤ fy/γm0) | 236.1 N/mm² | |
| 7.1.2 | Design compressive strength Pd | Ae fcd = 4,014 × 236.1 / 1000 | 947.6 kN |
Axial compression checkOK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| 7.1.2 | Governing strength | minimum of the axes - buckling about z-z | Pd = 947.6 kN | |
| 7.1.2 | Design axial force | P = 902.1 kN | ||
| 7.1.2 | P ≤ Pd | 902.1 ≤ 947.6 (ratio 0.952) | OK | OK |
8. Column base
Slab base design (Cl. 7.4)OK
| Reference | Description | Calculation | Result | |
|---|---|---|---|---|
| 7.4.1 | Bearing strength of concrete | 0.6 fck = 0.6 × 25 | 15.0 N/mm² | |
| 7.4.1 | Area required | P / (0.6 fck) = 902,086 / 15.0 | 60,139 mm² | |
| Projection beyond the column | required 13; min. for anchors 2.5 d = 60 | 60 mm | ||
| Plate size L × B | column 219.1 × 219 + projections | 340 × 340 mm | ||
| 7.4.1 | Bearing pressure w | P / (L B) = 902,086 / (340 × 340) | 7.80 N/mm² | OK |
| 7.4.3.1 | Projections a, b | larger / smaller projection beyond the column | 60 / 60 mm | |
| 7.4.3.1 | Thickness required ts | √[2.5 w (a² − 0.3 b²) γm0 / fy] with fy = 250 | 14.8 mm | |
| 7.4.3.1 | ts ≥ flange thickness | tf = 6 mm | ||
| Plate provided | E250 plate | 16 mm | OK | |
| Anchor bolts (nominal, axial load) | 4-M24 grade 4.6, 500 mm embedment | |||
| 7.4.3 | Column to base connection | column end machined for full bearing; 6 mm fillet weld all round | ||
| Pedestal | M25, 540 × 540 mm, 40 mm non-shrink grout |
9. Detailing notes
- Fabrication, erection and tolerances to IS 800 Sections 15 and 17; out-of-plumb not to exceed H/1000.
- Bolts to IS 1364 / IS 1367 with washers; holes drilled or sub-punched and reamed.
- Welding to IS 816 with E41 electrodes; minimum fillet size per IS 800 Table 21.
- Surface preparation and painting per the project specification (IS 800 Section 15).
10. Member drawing
Cross section, buckling elevations, buckling curves, base plate and design summary on one A3 sheet.