European Rebar Sizes — EN 10080 Bar Dimensions

Reinforcing steel bars for European concrete construction follow EN 10080:2005 and EN 1992-1-1. Bar diameters, cross-sectional areas, masses, and mechanical properties including yield strength, elongation, and bendability are standardised across all EU member states.

European rebar designations use nominal diameter in millimetres. Standard grades provide yield strengths suitable for EN 1992 concrete design. Ductility classes A, B, and C control the maximum bar diameter permitted in plastic design zones and seismic applications.

Quick access: EN 1992 Concrete Design → | EN 1993 Steel Grades → | EN 1993 Column Buckling → | Rebar Spacing Chart →

Code Reference: EN 10080:2005 and EN 1992-1-1

EN 10080:2005 specifies dimensions, tolerances, mechanical properties, and testing requirements for reinforcing steel. EN 1992-1-1:2004 provides the design rules for reinforced concrete using bars conforming to EN 10080. Always verify bar availability with local suppliers — not all diameters are stocked in all regions.

Standard Rebar Diameters and Section Properties

Grade Designations and Mechanical Properties

EN 10080 uses the designation B500 (nominal yield strength 500 MPa), followed by the ductility class:

B500C is mandatory for seismic design per EN 1998-1 in ductility classes DCM and DCH. The higher total elongation requirement (Agt (\geq 7.5%)) ensures the reinforcement can sustain the inelastic deformations imposed by the design seismic action without fracture. B500A is limited to welded mesh fabric and stirrups in non-seismic zones.

Rib Geometry Requirements

EN 10080 requires specific rib geometry to ensure adequate bond with concrete:

The relative rib area fR is the critical parameter for bond strength. Insufficient rib area reduces the design bond stress (f_{bd}) in EN 1992-1-1 Clause 8.4.2.

Bendability and Anchorage

EN 10080 specifies bendability requirements to ensure bars can be bent to the minimum mandrel sizes per EN 1992-1-1 Table 8.1N:

For a 20 mm bar: min bend diameter = 7 (\times) 20 = 140 mm. The bar must be bent 180° around a mandrel of this diameter without cracking. The bend test per EN 10080 Clause 9.3 involves bending the bar 90° and then 20° further, checking for visible cracks.

Weldability of EN 10080 Rebar

EN 10080 does not automatically guarantee weldability — the chemical composition must be verified:

For B500B: typical CEV = 0.35-0.50%. CEV (\leq 0.40%) is recommended for welding without preheat. For tack welding during assembly, CEV (\leq 0.52%) is the practical maximum per EN 1992-1-1.

Worked Example — Rebar Area Calculation

Problem: Determine the number of 20 mm bars required to provide As = 1,850 mm² reinforcement in a beam section.

Area of one 20 mm bar: (A_s = \pi \times 20^2 / 4 = 314) mm² Number required: (n = 1,850 / 314 = 5.89 \rightarrow) use 6 bars (A_s,prov = 1,884 mm²)

Check minimum spacing per EN 1992-1-1 Clause 8.2: Min clear distance: (\max(20\text{ mm}, 20\text{ mm} + 5\text{ mm}, 16\text{ mm}) = 25) mm In a 300 mm wide beam with 30 mm cover and 8 mm stirrups: available width = 300 - 2(30 + 8) = 224 mm Space for 6 bars at 20 mm: (6 \times 20 + 5 \times 25 = 245) mm (> 224) mm — space is insufficient. Option: use 2 layers of 3 bars, or increase beam width to 350 mm.

Design Resources

• EN 1993 Steel Grades
• European Steel Properties
• EN 1993 Bolt Capacity
• IPE/HEA/HEB Beam Sizes
• All European References

Frequently Asked Questions

What rebar sizes are available per EN 10080? EN 10080 covers bar diameters from 6 mm to 50 mm. Standard sizes are: 6, 8, 10, 12, 14, 16, 18, 20, 22, 25, 28, 32, 36, 40, and 50 mm. In practice, diameters 10, 12, 16, 20, 25, and 32 mm are the most commonly stocked sizes across European rebar suppliers. The 6 mm and 8 mm bars are typically supplied in coils for mesh production. Bars larger than 40 mm (i.e., 50 mm) are special-order items with longer lead times. The cross-sectional area scales with the square of the diameter: a 32 mm bar (804 mm²) has 2.6 times the area of a 20 mm bar (314 mm²).

What are the EN 10080 ductility classes? Three ductility classes are defined based on total elongation at maximum load (Agt): Class A (low ductility, Agt (\geq 2.5%)), Class B (medium ductility, Agt (\geq 5.0%)), Class C (high ductility, Agt (\geq 7.5%)). B500C is mandatory for seismic applications per EN 1998-1 Clause 5.5.1.2 for primary seismic members in DCM and DCH. B500B is the standard grade for general reinforced concrete in non-seismic regions. B500A is restricted to welded mesh fabric, stirrups, and secondary reinforcement because its limited ductility cannot sustain the deformation demands of primary members. The ft/fy ratio also varies: B500A (\geq 1.02), B500B (\geq 1.08), B500C (\geq 1.08) with a higher minimum ft (550 vs 540 MPa).

How does EN 10080 rebar compare to ASTM A615 (US) or AS/NZS 4671 (Australia)? EN 10080 B500B is roughly equivalent to ASTM A615 Grade 60 (fy = 420 MPa in the US system uses different units; 500 MPa ≈ 72.5 ksi — no direct ASTM equivalent at 500 MPa). The nearest ASTM grade is Grade 60 (420 MPa) or Grade 75 (520 MPa) for larger bars. AS/NZS 4671 uses the D500L grade with N (normal) ductility corresponding to B500B, and E (earthquake) corresponding to B500C. Key differences: US bars are denoted by imperial sizes (#4 = 12.7 mm, #5 = 15.9 mm). EN 10080 specifies rib geometry requirements (relative rib area) that are not in ASTM A615 and provides more rigorous ductility classification. For projects specifying EN 10080 outside the EU, verify local availability of B500B/B500C with European suppliers.

What is the minimum concrete cover for EN 10080 rebar per EN 1992-1-1? Minimum cover cmin per EN 1992-1-1 Clause 4.4.1 depends on the exposure class and bond requirements. For a beam in exposure class XC1 (interior, dry), cmin = 15 mm for bond + 10 mm for environment = 15 mm (bond governs). For XC3/XC4 (exterior, moderate humidity or cyclic wet-dry), cmin = 25 mm for bond + 25 mm for environment = 25 mm. For XD/XS (de-icing salts or seawater), cmin = 40-55 mm depending on the specific class. The nominal cover is cnom = cmin + Δcdev where Δcdev = 10 mm (tolerance). So for an exterior beam (XC3/4): cnom = 25 + 10 = 35 mm. The cover is measured to the outermost bar (including stirrups), not the main longitudinal bars.

Is EN 10080 rebar suitable for welding? EN 10080 rebar can be welded, but the weldability depends on the chemical composition. The carbon equivalent value (CEV) per EN 10080 Clause 6.2 limits CEV to (\leq 0.52%) for B500B, but CEV (\leq 0.40%) is recommended for tack welding without preheat. For full-strength butt welds (flash welding or mechanical couplers), a qualified welding procedure specification (WPS) is required per EN 1011-2. B500B with CEV 0.35-0.40% is readily weldable with standard procedures. For cross-welding in mesh production, the resistance welding process is factory-controlled and does not require preheat regardless of CEV. Tack welding for fixing bars before concreting is permitted per EN 1992-1-1 provided the weld quality does not significantly reduce the bar cross-section.

Reference only. Verify all values against the current edition of EN 10080:2005 and EN 1992-1-1. This information does not constitute professional engineering advice.