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18.104.22.168 Mean Curvatures
The mean curvatures arising with the selected Tension-Stiffening approach are determined from the calculations for pure state I and pure state II.
The underlying Tension Stiffening model described in book 525  considers the concrete's tension stiffening effect between the cracks by means of a reduction of the steel strain. The required parameters are determined as follows.
Steel stress in state II for crack formation:
σsr1,II = 166.12 N/mm2
Steel stress in state II:
σs1,II = 242.27 N/mm2
Hence, we will have a closer look at the final crack state.
- εsm = εs2,II - βt ∙ (εsr,II - εsr,I)
- εsm = 1.211 - 0.306 ∙ (0.8306 - 0.199) = 1.0177 ‰
- εs2,II = 1.211 ‰ : steel strain in state II
- εsr1,II = 0.8306 : steel strain for crack internal force in state II
- εsr1,I = 0.199 ‰ : steel strain for crack internal force in state I
- βt = 0.306 : load duration factor of available action
From the mean curvature (1/r)z,m and the relation
the secant stiffness in the corresponding node results.
- My = 17.64 kNm : available moment
- (1/r)z,m = 1.226 ⋅ 10-2m-1 : steel strain for crack internal force in state II