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Why there are deviations when calculating the elastic critical moment Mcr according to DIN 18800‑2 and EC 3?
Generally, the calculation of the ideal elastic critical moment Mcr according to DIN 18800 and EC 3 uses the same equation. However, there is an important difference.
DIN 18800‑2 simplifies the factor of the load application point and sets this to 0.5.
On the contrary, EC 3 determined this factor C2 more precisely (LTB 5 manual, Chapter 3.4.3). Depending on the load application, the value of the factor C2 is between 0.41 and 1.562.
If you define the load application point equal to the centroid (doubly symmetric cross-section implied), the Mcr factor is identical according to DIN 18800‑2 and EC 3.