EuropeEurocode 2
Column loads link from beam reactions above to footing calculations below automatically. Design rectangular concrete columns to Eurocode EN 1992-1-1:2004 with axial and biaxial bending checks, interaction diagrams, and second-order effects.
The Calcs.com rectangular concrete column calculator to Eurocode 2 enables the easy and accurate design and analysis of concrete columns. With quick to interpret traffic light checks, and interactive column interaction diagrams, the concrete column calculator enables fast, accurate concrete design to Eurocode standards.
Method & scope
Calculation method
Structural model and load combinations
You define the column by its overall depth and width, total height, and effective buckling lengths about each axis. Applied actions follow EN 1991, and the calculator builds ULS and SLS load combinations to EN 1990:2002 from the permanent, variable, and wind load cases entered. An unfactored load analysis is carried out alongside the combined analysis so that serviceability effects are assessed under the correct combination. The design axial compression force and the design moments about the major and minor axes are then carried into the resistance checks.Second-order effects
Slenderness and second-order effects are evaluated to EN 1992-1-1:2004 Cl 5.8.3 using the effective buckling lengths and the effective creep ratio. A minimum eccentricity is applied to the compression force about each axis, so that even nominally concentric columns carry a design moment. These effects amplify the first-order moments before the resistance checks, capturing the additional demand from column deflection under load.Axial resistance and moment resistance
The maximum design axial compression resistance is computed to Cl 6.1 from the concrete compression block and the longitudinal reinforcement, using the design concrete compressive strength (governed by the partial factor for concrete and the long-term coefficient), the concrete ultimate compressive strain, and the design yield strength of the steel. The design moment resistance about each axis is found considering the coincident axial force, with a secant method solving the neutral axis depth so that internal forces balance the applied axial load. Each axis reports utilization = design moment / design moment resistance ≤ 1.0.Column interaction diagrams and biaxial bending
For each axis the calculator constructs a column interaction diagram, including the balanced-failure point, that plots the axial-moment capacity envelope of the section. The design demand is plotted against the envelope so the margin to capacity is visible directly. The two axes are then combined through the Eurocode 2 biaxial bending criterion (Cl 5.8.9), which raises the major-axis and minor-axis moment ratios to an exponent dependent on the axial load level and requires their sum to be ≤ 1.0.Crack control
Crack control at the serviceability limit state follows EN 1992-1-1:2004 Cl 7.3.2 and Cl 7.3.4. The calculator evaluates the calculated crack width against the maximum allowable crack width, using the coefficient for bond properties, coefficients for crack spacing, and the strain in the extreme tensile fiber at first cracking. Separate secant-method solutions for the neutral axis depth at cracking are run for major-axis and minor-axis bending so cracking is assessed for both directions.How to use it
1
Open the calculator
Open it from Run calc in the About this calculator panel above.
2
Enter your inputs
Work through the input sections from top to bottom. Click any input label to see its reference explanation, clause, conditions and assumptions. See Checks, References, Conditions and Assumptions.
3
Review the results and export
Check the utilization of each governing check in the summary, then export a PDF report. See Views and Export.
Common questions
What design standard does this calculator use?
What design standard does this calculator use?
The calculator designs and analyses rectangular reinforced concrete columns to EN 1992-1-1:2004 (Eurocode 2). Load combinations follow EN 1990:2002 and actions follow EN 1991. Partial factors for concrete and reinforcing steel, and the coefficient for long-term effects on compressive strength, can be adjusted per the relevant National Annex.
What are the key inputs?
What are the key inputs?
Key inputs include the overall depth and width of the cross-section, total column height, effective buckling lengths for both axes, nominal concrete cover, concrete strength class, and the longitudinal reinforcement arrangement (total number of top-and-bottom bars and left-and-right bars, bar diameter, and ductility class). You also set the link spacing for transverse reinforcement, the effective creep ratio, and the design axial force and moments about each axis.
What checks and outputs does it produce?
What checks and outputs does it produce?
The calculator checks ULS axial resistance (EN 1992-1-1:2004 Cl 6.1), design moment resistance about the major and minor axes considering the coincident axial force, and the biaxial bending criterion (Cl 5.8.9). It also runs SLS crack control and crack width checks (Cl 7.3.2 and Cl 7.3.4). Results are shown as traffic-light pass or fail alongside interactive column interaction diagrams.
How does it handle biaxial bending and slenderness?
How does it handle biaxial bending and slenderness?
The column is checked for combined axial load and moment about both the major and minor axes, then combined through the Eurocode 2 biaxial bending criterion (Cl 5.8.9). Second-order effects are evaluated to Cl 5.8.3 using the effective buckling lengths and effective creep ratio, and a minimum eccentricity is applied to the compression force about each axis.
What do the column interaction diagrams show?
What do the column interaction diagrams show?
The interaction diagrams plot the axial-moment capacity envelope of the section for major-axis and minor-axis bending, including the balanced-failure point. The design demand is plotted against the envelope so you can see the margin to capacity at a glance. A secant method solves the neutral axis depth for the design moment resistance at each load level.
Does this calculator support load linking with beam and footing calculations?
Does this calculator support load linking with beam and footing calculations?
Yes. The axial load at the column top can be linked from the reactions of beams framing in above, and the column base reaction can be linked into a connected footing calculation. When an upstream beam load changes, the column and its footing update automatically, so the full beam-to-column-to-footing load path stays consistent with no manual re-entry of reactions.
Next steps
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