How do I verify a steel column per NBR 8800?
Standards & Codes
NBR 8800:2008 column verification follows these steps: (1) Classify the cross-section (Class 1-4 based on width-to-thickness ratios), (2) Calculate gross area, effective area and radii of gyration, (3) Determine unbraced lengths and effective length factors (K from Anexo E), (4) Compute the reduced slenderness λ = √(Qn·Ny/Ne) where Ne is the Euler buckling load, (5) Read the reduction factor χ from the stability curve (NBR 8800 Table 2), (6) Compute design compressive resistance Nc,Rd = χ·Qn·Ag·fy/γa1 where γa1 = 1.10, (7) Compare Nc,Sd ≤ Nc,Rd. If the column also has bending moment, use the interaction equation from NBR 8800 §5.5.1.2. CalcSteel executes all of these steps automatically when you select NBR 8800 as the design standard and click Calculate.
Key takeaways
- NBR 8800 was first published in 1986, replacing allowable-stress design with the limit-states method; the 2008 second edition broadened composite design, and a third edition arrived in 2024.
- The column check reduces to one expression: Nc,Rd = chi*Q*Ag*fy/gamma_a1, with the reduction factor chi computed from the reduced slenderness lambda0.
- NBR 8800 adopts the same single column curve as AISC 360 (the 0.658 exponential + Euler form first published in AISC LRFD 1986), unlike Eurocode 3's five separate buckling curves.
- Software turns a multi-page hand calc into seconds: it finds the elastic buckling force Ne, derives lambda0, evaluates Q for local buckling, and reports the demand-to-capacity ratio.
Full guide
How Do I Verify a Steel Column per NBR 8800?
Step-by-step with figures and sources — 9 min read
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