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2.3.6 Determination of Required Reinforcement
Determination of Required Reinforcement
To determine the dimension of the necessary reinforcement area, the design axial force to be resisted nφ in the respective reinforcement direction φ is divided by the reinforcing steel stress on the yield strength.
The steel stress at yield is defined differently depending on the standard and the concrete strength class. Furthermore, for the design, the respective partial safety factor for the reinforcing steel has to be considered.
If the reinforcement is in compressive strain instead of tension, the steel stress for the allowable concrete compression at failure will be determined. It is the same in all standards and equals 2 ‰. Thus, the steel stress can be determined by using the modulus of elasticity as follows:
If the steel stress is greater than the steel stress at yielding, the steel stress at yielding is used. However, a compression reinforcement is determined only if the resistant axial force nstrut,d per meter of the concrete is smaller than the acting, compression-inducing design axial force. The compression reinforcement is then designed for the difference of the two axial forces.