Slenderness and second-order effects
Classifies slenderness per EN 1992-1-1 §5.8.3 and applies the nominal curvature method §5.8.8 when λ exceeds λ_lim.
SKL-000009 · Skill
EN 1990EN 1992-1-1Design a reinforced concrete column to Eurocode 2
Describe the column to Mia in your own words. Height, cross-section, concrete class and the design forces at the ends are enough to start. She classifies the slenderness, applies second-order effects using the nominal curvature method and designs the required longitudinal reinforcement for you. The result is a complete EN 1992-1-1 verification with transparent formulas, assumptions and detailing checks, ready to download as a PDF report.
Mia guides you step by stepShe guides you through the inputs and explains the results.
Worked example
Braced rectangular column, 300×300 mm, C30/37
- Height and support
- 4.0 m, braced, pinned-pinned
- Cross-section
- 300 × 300 mm rectangular
- Concrete class
- C30/37
- Steel grade
- B500 (fyk = 500 N/mm²)
- Design axial force
- NEd = 1200 kN
- First-order end moments
- M01 = 20 kNm, M02 = 40 kNm
Braced column, pinned at both ends, height 4.0 m, rectangular section 300 x 300 mm, C30/37, B500, cnom = 35 mm, NEd = 1200 kN, first-order end moments M01 = 20 kNm, M02 = 40 kNm, effective creep ratio phi_ef = 2.0, DIN EN 1992-1-1/NA (DE). Run the design check and propose reinforcement.
Required inputs
- Column height L and boundary conditions (braced or unbraced)
- Design internal forces NEd and first-order end moments M01, M02
- Cross-section dimensions (rectangular b×h or circular d)
- Concrete class and reinforcing steel grade
- Nominal cover cnom or exposure class
- Effective creep ratio φef or loading age and humidity
What you receive
- Effective length l0 per EN 1992-1-1 §5.8.3.2
- Slenderness ratio λ and limit λlim classification
- Second-order eccentricity e2 and total design moment MEd
- Required reinforcement area As,req
- Minimum and maximum reinforcement per §9.5.2
- Proposed bar arrangement with governing utilisation check
Prepare your calculation
Configure your column
System sketch
L = 4 mNEd = 1200 kNM01 = 20 kNmM02 = 40 kNm
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Inputs completeReady to calculate
What this skill checks
Cross-section reinforcement design
Determines required symmetric reinforcement A_s,req using the rectangular stress block of §3.1.7 by iteration or design-chart approach.
Detailing checks per §9.5
Verifies A_s,min and A_s,max limits, minimum bar diameter, and transverse reinforcement spacing against EN 1992-1-1 §9.5.
Practical bar arrangement proposal
Proposes a reinforcement layout (e.g. 4 Ø20 + links Ø8/300) satisfying both the required area and the detailing rules.
Normative basis
Standards & references
The checks follow these standards. Nationally determined parameters come from the National Annex selected in the form.
EN 1992-1-1
WithdrawnEurocode 2: Design of concrete structures – Part 1-1: General rules and rules for buildings
Edition used: DIN EN 1992-1-1:2011-01 (EN 1992-1-1:2004 + AC:2010) + DIN EN 1992-1-1/A1:2015-03
- §3.1.6
- §5.8.3.2
- §5.8.8
- §6.1
- §9.5
DIN MediaNewer edition: DIN EN 1992-1-1:2025-09 (EN 1992-1-1:2023)
| Country | National Annex | Factors | Source |
|---|---|---|---|
| DE | DIN EN 1992-1-1/NA:2013-04 + DIN EN 1992-1-1/NA/A1:2015-12Current | γC = 1.50γS = 1.15αcc = 0.85 | DIN Media |
| EN | Recommended valuesEN 1992-1-1:2004 + AC:2010 + A1:2014 | γC = 1.50γS = 1.15αcc = 1.00 | – |
Status checked on
EN 1990
CurrentEurocode: Basis of structural design
Edition used: DIN EN 1990:2021-10 (EN 1990:2002 + A1:2005 + A1:2005/AC:2010)
- §6.4.3.2
DIN MediaNewer edition: EN 1990:2023 (CEN; coexistence with the first generation until 2028-03-30)
| Country | National Annex | Factors | Source |
|---|---|---|---|
| DE | DIN EN 1990/NA:2010-12 + DIN EN 1990/NA/A1:2024-05Current | γG = 1.35γQ = 1.50 | DIN Media |
| EN | Recommended valuesEN 1990:2002 + A1:2005 + A1:2005/AC:2010 | γG = 1.35γQ = 1.50 | – |
Status checked on
Frequently asked questions
Frequently asked questions
InputsWhich inputs do you need from me for a complete concrete column design check?
Mia needs column height and boundary conditions, design axial force NEd and first-order end moments M01 and M02, cross-section dimensions, concrete class, steel grade, nominal cover or exposure class, and the effective creep ratio φef (or loading age and humidity to estimate it).
ScopeWhen is the nominal curvature hand method not sufficient for a concrete column?
The hand method covers isolated braced columns under axial force and uniaxial bending. For biaxial bending beyond §5.8.9, unbraced frames, or walls, Mia states the method is not sufficient and recommends building an RFEM model with the Concrete Design add-on.
VerificationWhat minimum and maximum reinforcement applies to a 400×400 mm column with NEd = 900 kN?
Per EN 1992-1-1 §9.5.2 (recommended values), As,min is the greater of 0.10·NEd/f_yd and 0.002·Ac, and As,max is 0.04·Ac; the German National Annex sets other limits. Mia calculates both limits, proposes a bar layout, and checks the minimum bar diameter (§9.5.2) and the link spacing (§9.5.3).
VerificationDoes Mia use recommended EN 1992-1-1 values or National Annex values?
Mia defaults to recommended values (γC = 1.50, γS = 1.15, αcc = 1.00) and flags that the National Annex may differ. For example, the DIN NA uses αcc = 0.85. You can supply your own NA parameters and Mia will apply them.
Ready for your first check?
Start with the example and adapt it to your structural system.
New calculation