Input Data

• Concrete characteristic strength: f_ck = 30 MPa
• Type of reinforcement / tendon: = Reinforcement bar
• Maximum diameter of reinforcement / tendon: Φ = 20 mm
• Environment exposure class for durability (XC, XD, XS): = XC4
• Environment exposure class for attack (XF, XA): = X0
• Design working life: = 50 years
• Member with slab geometry: = No
• Concrete cast against uneven surface: = None
• Special quality control of the concrete production: = No
• Nominal aggregate size greater than 32 mm: = No

Nationally Defined Parameters

• Allowance for deviation to calculate nominal cover: Δc_dev = 10
• Nationally Defined Parameters: = CEN default

Calculation of structural class

The structural class is calculated according to the rules specified in EN1992-1-1 Table 4.3N:

• The initial structural class is S4 (corresponding to the reference design working life of 50 years)
• The minimum structural class is S1

Therefore the structural class is S4.

Calculation of concrete cover for durability

Minimum concrete cover for protection against corrosion (exposure classes XC, XS, XD)

For reinforcement steel the minimum cover for durability against corrosion c_min,dur is calculated in accordance with EN1992-1-1 Table 4.4N.

For structural class S4 and exposure class XC4 the minimum cover for durability is equal to c_min,dur = 30.0 mm.

Minimum concrete cover for protection against freeze/thaw or chemical attack (exposure classes XF, XA)

Where freeze/thaw or chemical attack on concrete (exposure classes XF, XA) is expected special attention should be given to the concrete composition (see EN 206-1 Section 6). According to EN 1992-1-1 §4.4.1.2(12) the minimum concrete cover calculated for the protection of concrete against corrosion (exposure classes XC, XS, XD) will normally be sufficient for the protection of concrete against attack (exposure classes XF, XA).

Therefore the minimum concrete cover for durability is c_min,dur = 30.0 mm.

Calculation of concrete cover for bond

The minimum cover for bond c_min,b is calculated in accordance with EN1992-1-1 §4.4.1.2(3).

For reinforcement bars the minimum cover for bond is calculated in accordance with EN1992-1-1 Table 4.2N as: c_min,b = 1.0⋅Φ, where Φ is the diameter of the reinforcement bar (or equivalent diameter of bundled bars).

Therefore minimum cover for bond is c_min,b = 20.0 mm.

Calculation of minimum concrete cover

According to EN1992-1-1 §4.4.1.2(2)P the greater value of concrete cover satisfying the requirements for both bond and durability is used:

c_min = max {c_min,b, c_min,dur + Δc_dur,γ - Δc_dur,st - Δc_dur,add, 10 mm}

According to EN1992-1-1 §4.4.1.2(6) the additive safety element is Δc_dur,γ = 0.0 mm.

The following modification factors are not applicable:

• Reduction of minimum cover for use of stainless steel Δc_dur,st = 0 mm
• Reduction of minimum cover for use of additional protection Δc_dur,add = 0 mm.

Therefore the minimum concrete cover is calculated as:

c_min = max {20.0 mm, 30.0 mm + 0.0 mm - 0 mm - 0 mm, 10 mm } = 30.0 mm

Calculation of nominal concrete cover

The nominal concrete cover c_nom is calculated by adding to the minimum cover c_min the allowance for deviation Δc_dev, as specified in EN1992-1-1 §4.4.1.3(1)P.

In this calculation the allowance for deviation is considered as Δc_dev = 10.0 mm.

The required nominal concrete cover is:

c_nom = c_min + Δc_dev = 30.0 mm + 10.0 mm = 40.0 mm

Therefore the required nominal concrete cover is c_nom = 40.0 mm.

Calculation of minimum concrete class for durability

The required minimum concrete class for durability is calculated in accordance with EN1992-1-1 Annex E Table E.1 depending on the exposure class.

• The exposure class for the case of concrete corrosion is XC4 and the required minimum concrete class is C30/37.
• The exposure class for the case of attack to concrete is X0 and the required minimum concrete class is C12/15.