Rebar for Beams & Lintels: Sizes, Detailing & Quantities

How Beams and Lintels Use Reinforcing Steel

Beams and lintels span horizontally between supports, developing bending moments and shear forces as they carry load from slabs, walls or roofs. In a simply-supported beam, the bottom zone is in tension (where the concrete cracks) and requires main tension reinforcement; the top zone is in compression. Continuous beams (integral with columns or walls) also develop hogging moments at supports, requiring top steel in those zones.

Shear forces are resisted by vertical links (stirrups) — closed rectangular or U-shaped bars that enclose the main steel and are bent from 8 mm or 10 mm B500B wire. Lintels over door and window openings follow the same principles but at smaller scale, often using 2–4 bars of 12–16 mm over short spans.

B500B (DIN 488, EN 10080) is the standard grade for both main bars and links in German and EU beam design. Its 500 MPa yield and high ductility (k ≥ 1.08, Agt ≥ 5.0 %) are relied upon in Eurocode 2 moment redistribution and rotation capacity calculations.

Typical Bar Sizes for Beam Tension and Compression Zones

Shear Link Sizing and Spacing

Links are the critical element preventing shear failure in beams. Eurocode 2 §9.2.2 governs link requirements:

• Minimum link diameter: 6 mm (but typically 8 mm or 10 mm for practical handling and weld capacity if required).
• Maximum link spacing (longitudinal): 0.75d, where d is the effective depth. For beams with significant shear demand, this is often reduced to 0.5d or less near supports.
• Minimum shear reinforcement ratio: ρw,min = 0.08√fck/fyk (approximately 0.08 for C25/30 concrete and B500B).
• Anchorage of links: Links must be fully anchored — typically bent through 135° with a tail of at least 10 diameters (or 70 mm) around the tension steel.

Our pre-bent stirrups and cut-and-bend service supplies links to DIN 488 shape codes, reducing cage assembly time and bar-bending labour on site.

Concrete Cover for Beams and Lintels

Cover is measured to the outermost bar (usually the link). Minimum cover by exposure class under Eurocode 2:

• XC1 (internal, dry): 15–20 mm minimum (cnom typically 25 mm)
• XC2–XC3 (external, sheltered): 25–30 mm minimum (cnom 35 mm)
• XC4 / XD1 (cyclic wet/dry, or de-icing salts): 35–40 mm minimum
• XD3 / XS (severe chloride or marine): 45–55 mm minimum

External lintels are typically XC3 or XC4 and require at least 35 mm cnom; always verify with the structural engineer’s exposure classification. Insufficient cover leads to corrosion-induced cracking — a leading cause of durability failure in building structures.

Sourcing Beam Rebar: Export Documentation and Supply

Beam and lintel reinforcement is typically ordered as straight bars in 6 m or 12 m stock lengths (cut-and-bent on site or by a fabricator) or as prefabricated cages supplied to the bar bending schedule. We supply B500B bars from 8 mm to 40 mm with EN 10204 3.1 Mill Test Certificates confirming heat-specific yield strength, tensile strength, elongation and chemical analysis. CE Declaration of Performance, Certificate of Origin and seaworthy packing are standard on all export orders.

For project buyers needing continuity between structural elements, see also: Rebar for RC Columns, Rebar for Slabs, and our full applications overview. Submit your bar schedule via the quote form for a prompt response.