KEVOS® MAKEOS · Strength
Tube Post with Eccentric Load (Section, Secant Formula, Load Factor)
Is this round tube post or column safe under a load applied off its centreline, and how much more load would bring it to yield?
Check of a round tube post or strut carrying an axial load at an eccentricity (a bracket, a sign arm or an offset beam seat): area, second moment, radius of gyration and slenderness of the tube, Euler buckling load, and the secant-formula peak stress and load factor to first yield (as the eccentrically loaded column tool), checked against your load factor and slenderness limit.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Tube outside diameter | mm | Outside diameter of the tube. |
| Wall thickness | mm | Wall thickness of the tube. |
| Length | mm | Length of the post or strut. |
| Effective length factor | Effective length factor for the end fixity (2 for a free-standing post fixed at the base). | |
| Axial load | N | Axial compressive load. |
| Eccentricity of load | mm | Distance from the tube centreline to the line of the load. |
| Elastic modulus | GPa | Elastic modulus. |
| Yield strength | MPa | Yield strength of the tube. |
| Required load factor | Factor on load you need before first yield. | |
| Largest slenderness KL/r | Largest slenderness ratio your code allows. |
Method and formulas
- A = π (D² − d²) ÷ 4; I = π (D⁴ − d⁴) ÷ 64; r = √(I ÷ A); slenderness = K L ÷ r.
- σ_max = P ÷ A [1 + (e c ÷ r²) sec(K L ÷ 2r × √(P ÷ A E))] (as the eccentrically loaded column tool).
- Load factor = the multiple of P at which σ_max reaches yield.
- Example: the tube peaks at 32.093 MPa; yield comes at 4.4217 × the load; KL/r = 156.46.
Limitations
- Elastic secant formula to first yield; it does not include residual stresses or initial crookedness beyond the eccentricity.
- Local buckling of thin walls is not checked.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Check a pipe post carrying a bracket load
- Size a column with an offset beam seat
- Check a cantilever sign post in compression
Who it is for
- Structural designers
- Design engineers
- Fabrication engineers
What you get
- Section properties and slenderness
- Euler load and peak stress
- Load factor to yield
Interpreting the result
- Eccentricity, not slenderness, usually controls short posts: move the load line closer to the centre if you can.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 281–287, 234–246. Topic reference; no source tables or recommended settings are reproduced.
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Open the Tube Post with Eccentric Load (Section, Secant Formula, Load Factor) calculator
