d where as is the stress in the longitudinal steel and x is the height of the compression zone.
In general the requirement 5» < 0.004 l will be governing. Substituting this equation in (11.1) it is found that
For the height x of the compression zone in the linear elastic cracked state it is known that
where p1 = longitudinal reinforcement ratio and n = Es/Ec
For a concrete strength C20/25 the E-modulus, including creep effects, can be assumed to be Ec = 9000 MPa, so that n = 200,000/9000 = 22,2
For lightweight concrete Elc= ^e • Ec, where ^e is defined as
In Table 11.1 the values for x/d are calculated on the basis of Eq. (11.19), as a function of p1(%) and ^e see Eq. 11.2 in prEN1992-1-1
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