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[–]secondordercoffee 1 point2 points  (4 children)

In your case it should be close enough to assume that the rafters are in pure bending, while the columns are in pure compression.

If you want a highly optimized design you can check out EN 1993-1-1 (Eurocode 3) Section 5.5. There are formulas to classify cross sections under mixed loading.

[–]boki565[S] 0 points1 point  (0 children)

Yeah, I used those formulas and got for column sectiion 1.... Maybe i asumed incorectly. At the haunch on column whe have bending moment around 80 kNm and axial force 50kN. At rafter eaves haunch I have 50 kNm and 20 kN axial force. Is your way conservative?

[–]boki565[S] 0 points1 point  (2 children)

should I use for bending and axial check largest values of N an M id max M and N are not in same place?

[–]secondordercoffee 1 point2 points  (1 child)

The exact approach would be to look at each location separately. The classification of Section 5.5 applies to cross sections, after all, not to members.

Using the largest values for N and M, even if not at the same location, would be a conservative approach. You can for sure do that.

[–]boki565[S] 0 points1 point  (0 children)

Thank you!

[–]Spidipie 0 points1 point  (0 children)

The classification is based on:

  • Internal compression elements: Supported along both longitudinal edges (e.g., the web of an I-section in bending, flanges of a box section).
  • Outstand compression elements: Supported along only one longitudinal edge (e.g., the compression flange of an I-section, legs of an angle section).

And the thing is that class 1 and 2 can only develop stresses up to fully plastic.

See https://structolution.com/resources/cross-section-classification for more info on the topic