Engineering
Column Capacity Calculator
Estimate gross axial resistance, a simplified slenderness reduction, delivered column capacity, utilization, reserve and whole-column requirement.
Effective unsupported length-
Modeled slenderness ratio-
Simplified slenderness reduction-
Gross short-column capacity-
Modeled capacity per column-
Total installed modeled capacity-
Capacity minus entered load-
Demand utilization-
Exact columns required-
Whole identical columns required-
Decision view
Column load path and slenderness screen
Column load path and slenderness screenThe axial design load is placed on a vertical member whose entered material-area resistance is reduced by slenderness and the capacity factor.
Exact scenario comparisonUnsupported length (m) changes while all other entered assumptions remain constant.
| Unsupported length (m) | Effective unsupported length | Modeled slenderness ratio | Simplified slenderness reduction | Gross short-column capacity | Modeled capacity per column | Total installed modeled capacity | Capacity minus entered load | Demand utilization | Exact columns required | Whole identical columns required |
|---|
Period-by-period detail
Unsupported-length capacity cases
How to use Column Capacity Calculator
- Use consistent force and stress units.
- Enter the governing unsupported length and effective-length factor.
- Treat the result as a screening check only.
Calculator guide
Understanding Column Capacity Calculator
A preliminary column screen compares factored axial load with material-area resistance reduced for slenderness and the entered design factor.
Calculation method
How the calculation works
Compare entered column axial demand with a transparent area-stress reference reduced by a simplified slenderness factor. Section area multiplied by allowable material stress creates short-column resistance; unsupported length and radius of gyration create slenderness, which applies a bounded reduction before the safety factor.
Axial load path
Place the design load on the slender column
The elevation shows unsupported length, section resistance, derating and capacity reserve.
Worked situations
Practical examples
- A longer unbraced column can have lower delivered capacity without changing its section area.
- Adding identical columns divides the entered axial demand.
- A low utilization result does not replace connection or stability checks.
Better inputs
Useful tips
- Verify effective length from the actual frame.
- Use code-defined material resistance.
- Check combined axial load and bending separately.
Before relying on the result
Limitations and common mistakes
- This is not a code design.
- Local buckling, residual stress, imperfections, second-order effects, biaxial bending, fire, connections and load combinations are excluded.
- A licensed engineer must verify safety-critical work.
Reference
Key terms
- Slenderness ratio
- Effective unsupported length divided by radius of gyration.
- Gross axial resistance
- Section area multiplied by entered allowable stress.
- Utilization
- Design load divided by delivered modeled capacity.
Important note
Calculated from the entered values using the displayed engineering relationship. Confirm design values, load cases, safety factors, standards, and field conditions with a qualified professional.
Frequently asked questions
Can this approve a structural column?
No. It is only a preliminary comparison.
What radius of gyration should be used?
Use the governing weak-axis value for the actual section.
Does it include bending?
No. Beam-column interaction requires a code-based check.