RF-CONCRETE Surfaces – Online Manual Version 5

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RF-CONCRETE Surfaces – Online Manual Version 5

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2.6.4.8 Limitation of reinforcing steel stress

Limitation of reinforcing steel stress

In window 1.3 Surfaces, the tension stresses of the reinforcing steel reinforcement are limited to σs,max = 0.8 ⋅ fyk according to EN 1992-1-1, clause 7.2(5) (see Figure 2.90). For BSt 500 S (B), the maximum steel stress σs,max is thus determined as:

σs,max = 0.8 · fyk = 0.8 · 500 = 400 N/mm2 

The maximum stress σs,max is to be compared with the provided tension stress for both reinforcement directions.

The provided tension stress σs is determined as follows:

σs = αE · mEd · d - xIi,II 

where

Table 2.2

αE

relation of elastic moduli (Es / Ecm)

mEd

applied moment

d

effective depth

depth of concrete neutral axis

b

width of element (always 1m for plates)

as

provided tension reinforcement

ideal moment of inertia in state II

With the values calculated in chapter 2.6.4.6, the provided tension stresses σs,u,φ1 and σs,u,φ2 in the two reinforcement directions φ1 and φ2 can be determined as follows:

σs,u,ϕ1 = 6.061 · 3 674 · 17 - 4.1913 701 = 208.18 N/mm2 

σs,u,ϕ2 = 6.061 · 2 733 · 15.8 - 4.0211 677 = 167.09 N/mm2 

Figure 2.94 Maximum steel stresses in reinforcement direction 1 and 2

The existing tension stresses σs,-z,φ1 and σs,-z,φ2 are therefore smaller than the maximum steel stress σs,max (see Figure 2.90). The governing quotient of existing to allowable steel stress is available in the reinforcement direction φ1. The design is fulfilled.

Figure 2.95 Analysis of reinforcing steel stress