Rectangular stress distribution for the design of concrete cross-sections: the factors λ, η
Eurocode 2 part 1-1: Design of concrete structures 3.1.7 (3)
For the design of concrete cross-sections, a rectangular stress-strain distribution may be assumed as in Figure 3.5:
| λ = 0,8 for fck ≤ 50 MPa | (3.19) |
| λ = 0,8 - (fck - 50)/400 for 50 < fck ≤ 90 MPa | (3.20) |
| and | |
| η = 1,0 for fck ≤ 50 MPa | (3.21) |
| η = 1,0 - (fck - 50)/200 for 50 < fck ≤ 90 MPa | (3.22) |
| Note: If the width of the compression zone decreases in the direction of the extreme compression fibre, the value η fcd should be reduced by 10%. |
where:
- x
- is the neutral axis depth
- λ
- is the factor defining the effective height of the compression zone and the factor
- η
- is the factor defining the effective strength
- fck
- is the characteristic compressive strength of concrete, see Table 3.1
- fcd
- is the design compressive strength of concrete, see § 3.1.6 (1)P.
This application calculates the factors λ, η from your inputs.
