Combined Bending and Compression
Bending and Axial Compression (NDS section 3.9.2)
beam-columns are common
Zahn's Formula Considers/Combines
- column buckling
- lateral torsional stability
- beam-column interaction
Amplification Factor
- bending + axial compression more critical than bending + axial tension
- P-Δ effect (second-order effect)
source
- bending moment causes deflection
- axial load causes further deflection due to curved shape
- but mechanics of materials does not take this into account
- bending stress is amplified in interaction formula
General Interaction Formula (NDS section 15.4)
- axial compression
- biaxial bending
- P-Δ effect
- eccentric bending
- additional P-Δ effect
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