Engineering Eurocode 2 (EC2) – Concrete Design Overview & Tools
Quick reference for EN 1992-1-1: design philosophy, material factors, load combinations, section checks and links to dedicated Eurocode 2 calculators.
Eurocode 2 Toolbox (Concrete Design Calculators)
Use these dedicated calculators when you already know your actions and geometry. This page explains the concepts and formulas behind them.
EC2 Concrete Beam Flexural Design
Design longitudinal reinforcement for rectangular beams to EN 1992-1-1.
EC2 Shear Design
Check shear resistance with/without shear reinforcement.
EC2 Column Design
Axial load and bending checks for columns to EC2.
EC2 Punching Shear
Flat slabs and foundations around columns.
Note: Always check your National Annex. This page uses common default values from EN 1992-1-1.
1. What is Eurocode 2 (EN 1992-1-1)?
Eurocode 2 (EC2) is the European standard for the design of concrete structures. Part 1-1 (EN 1992-1-1) covers:
- Reinforced and prestressed concrete buildings and civil engineering works
- Normal-weight, lightweight and some special concretes
- Ultimate Limit States (ULS) and Serviceability Limit States (SLS)
EC2 is used together with:
- EN 1990 – Basis of structural design (safety formats, combinations)
- EN 1991 – Actions on structures (loads)
- National Annexes – country-specific parameters (γ-factors, cover, etc.)
2. Design Philosophy and Safety Format
Eurocode 2 uses the partial factor method:
- Characteristic material strengths are reduced by partial safety factors.
- Characteristic actions (loads) are increased by load factors.
- Design is checked at ULS (strength, stability) and SLS (cracking, deflection, vibration).
2.1 Design strengths
Concrete design compressive strength
\[ f_{cd} = \alpha_{cc} \cdot \frac{f_{ck}}{\gamma_c} \]
- \( f_{ck} \): characteristic cylinder strength (e.g. 30 MPa for C30/37)
- \( \alpha_{cc} \): long-term coefficient (often 0.85)
- \( \gamma_c \): partial safety factor for concrete (typically 1.50)
Steel design yield strength
\[ f_{yd} = \frac{f_{yk}}{\gamma_s} \]
- \( f_{yk} \): characteristic yield strength (e.g. 500 MPa)
- \( \gamma_s \): partial safety factor for steel (typically 1.15)
2.2 Load combinations (ULS)
For persistent and transient situations, a common combination (from EN 1990) is:
\[ \gamma_G \cdot G_k + \gamma_Q \cdot Q_{k,1} + \sum \gamma_Q \cdot \psi_{0,i} \cdot Q_{k,i} \]
- \( G_k \): permanent action (self-weight, finishes)
- \( Q_{k,1} \): leading variable action (e.g. imposed load)
- \( Q_{k,i} \): accompanying variable actions (wind, snow, etc.)
- \( \gamma_G, \gamma_Q \): partial factors for actions (e.g. 1.35, 1.5)
- \( \psi_{0,i} \): combination factors for variable actions
National Annexes may modify these values; always verify for your country.
3. Section Types and Stress–Strain Models
Eurocode 2 provides simplified stress–strain diagrams for concrete and steel.
3.1 Concrete stress block (rectangular sections)
For ULS flexural design, EC2 uses an equivalent rectangular stress block:
Resultant compressive force:
\[ C = \alpha \cdot f_{cd} \cdot b \cdot x \]
Lever arm:
\[ z \approx d - 0.4x \]
- \( b \): section width
- \( x \): neutral axis depth
- \( d \): effective depth (to tension reinforcement)
- \( \alpha \): factor depending on concrete class (often ≈ 0.8)
3.2 Steel stress–strain
Reinforcing steel is usually modelled as elastic–plastic with design yield strength \( f_{yd} \). For ULS:
- Tension reinforcement is typically assumed to yield: \( \sigma_s = f_{yd} \).
- Compression reinforcement may be limited by buckling and strain compatibility.
4. Flexural Design to Eurocode 2 (Beams & Slabs)
For a singly reinforced rectangular section under sagging bending:
- Choose concrete class (e.g. C25/30) and steel grade (e.g. B500B).
- Determine design bending moment \( M_{Ed} \) from load analysis.
- Compute design strengths \( f_{cd}, f_{yd} \).
- Check if section is singly or doubly reinforced (compare required depth with limiting depth).
- Calculate required tension reinforcement area \( A_s \).
Approximate required steel area (singly reinforced)
Assuming tension steel yields and compression block is within section:
\[ M_{Rd} = A_s \cdot f_{yd} \cdot z \]
Set \( M_{Rd} = M_{Ed} \) and solve for \( A_s \):
\[ A_s = \frac{M_{Ed}}{f_{yd} \cdot z} \]
with \( z \approx 0.9d \) for typical sections.
Eurocode 2 also specifies:
- Minimum reinforcement to control cracking.
- Maximum reinforcement ratio to ensure ductile behaviour.
- Bar spacing and cover requirements for durability and fire.
5. Shear Design to Eurocode 2
Shear resistance is checked in two stages:
- Concrete shear resistance without shear reinforcement \( V_{Rd,c} \).
- Shear resistance with shear reinforcement \( V_{Rd,s} \), if required.
Concrete shear resistance (simplified)
\[ V_{Rd,c} = \left[ C_{Rd,c} \cdot k \cdot (100 \rho_l f_{ck})^{1/3} \right] \cdot b_w \cdot d \]
- \( C_{Rd,c} \): coefficient (≈ 0.18 / γc)
- \( k = 1 + \sqrt{\frac{200}{d}} \le 2.0 \) (d in mm)
- \( \rho_l \): longitudinal reinforcement ratio
- \( b_w \): web width
- \( d \): effective depth
If \( V_{Ed} > V_{Rd,c} \), shear reinforcement is required:
Shear resistance with stirrups
\[ V_{Rd,s} = \frac{A_{sw}}{s} \cdot z \cdot f_{ywd} \cdot \cot\theta \]
- \( A_{sw} \): area of shear reinforcement within spacing s
- \( s \): stirrup spacing
- \( z \): internal lever arm (≈ 0.9d)
- \( f_{ywd} \): design yield strength of shear reinforcement
- \( \theta \): angle of compression struts (typically 21°–45°)
6. Serviceability Limit States (SLS)
Eurocode 2 requires checks for:
- Crack width (wk) – often limited to 0.3 mm or less depending on exposure.
- Deflections – span/depth ratios or explicit deflection calculations.
- Stress limitations in concrete and steel under frequent or quasi-permanent loads.
Crack control is typically handled by limiting bar spacing and ensuring minimum reinforcement area.
7. Cover, Durability and Fire
Eurocode 2 links nominal cover to:
- Exposure class (XC, XD, XS, XF, etc.)
- Fire resistance requirements (e.g. R60, R90)
- Bar diameter and bond conditions
National Annexes provide tables for minimum cover cmin and additional allowances (Δcdev).
8. When to Use Dedicated EC2 Calculators
Use the specialised Eurocode 2 calculators on CalcDomain when you:
- Have a specific member (beam, slab, column, footing) with known geometry and loads.
- Need fast iteration on reinforcement layouts and bar diameters.
- Want automatic checks for minimum/maximum reinforcement, spacing and code limits.
This overview page helps you understand the underlying formulas so you can interpret the calculator outputs and verify them by hand if needed.
Eurocode 2 – Quick Reference Tables
| Parameter | Typical value | Notes |
|---|---|---|
| γc (concrete) | 1.50 | Persistent/transient situations (check National Annex). |
| γs (steel) | 1.15 | Reinforcing and prestressing steel. |
| αcc | 0.85 | Long-term effects and unfavourable conditions. |
| z (lever arm) | ≈ 0.9 d | For typical rectangular sections in bending. |
| ULS load factors | 1.35 Gk + 1.5 Qk | Basic combination, may vary by National Annex. |
Eurocode 2 – Frequently Asked Questions
What is Eurocode 2 (EN 1992-1-1)?
Eurocode 2 is the European standard for the design of concrete structures. Part 1-1 covers general rules and rules for buildings, including reinforced and prestressed concrete. It defines material models, safety factors, detailing rules and design checks for beams, slabs, columns, walls and foundations.
What partial safety factors does Eurocode 2 use for concrete and steel?
For persistent and transient design situations, the recommended values are γc = 1.50 for concrete and γs = 1.15 for reinforcing and prestressing steel. National Annexes may specify different values, so always verify for your country and project type.
How do I calculate design strengths in Eurocode 2?
Design strengths are obtained by dividing characteristic strengths by partial safety factors. For concrete: \( f_{cd} = \alpha_{cc} \cdot f_{ck} / \gamma_c \). For reinforcing steel: \( f_{yd} = f_{yk} / \gamma_s \). These values are then used in ULS design equations for bending, shear, punching and axial load.
Which load combinations should I use with Eurocode 2?
Eurocode 2 itself does not define load combinations; it relies on EN 1990 and EN 1991. A common ULS combination is 1.35·Gk + 1.5·Qk for buildings, with additional variable actions multiplied by combination factors ψ. For SLS, frequent and quasi-permanent combinations are used with ψ1 and ψ2 factors. Always follow your National Annex.
What are the main design checks in Eurocode 2?
Key checks include: flexural resistance (bending), shear resistance, punching shear, axial load and combined bending in columns, crack width and deflection at SLS, minimum and maximum reinforcement ratios, anchorage and lap lengths, and detailing for ductility, durability and fire resistance.