An isolated reinforced masonry column designed to NBR 16868 uses a limit-state format with its own slenderness reduction coefficient, structured similarly to the Eurocode 6 masonry column example elsewhere in this series but calibrated against Brazilian masonry unit and execution standards.
Every check above runs automatically inside the Structyze Masonry Column / Pier module — this particular module is part of the full desktop catalogue rather than the free browser trial, since the trial only carries a curated flagship set. You can still try the free trial modules right now to see the same calculation style in action on RCC Beam, Column, Slab and a handful of others.
The Example We'll Use
- Column: 290 mm × 290 mm fully grouted structural block, height 3.2 m, pinned-pinned
- f_pk: 9 MPa, longitudinal reinforcement: 4-12.5 mm bars, f_yk: 500 MPa
- Design axial load N_Sd: 245 kN, design eccentricity: 20 mm
Working Through It
Slenderness index λ = H / t = 3200 / 290 = 11.0, within NBR 16868's standard workable range for this column type without requiring second-order amplification provisions beyond the code's standard reduction approach.
Slenderness-and-eccentricity reduction coefficient, combining λ and e/t = 20/290 = 0.069 per NBR 16868's design provisions, gives a reduction factor of approximately 0.79.
Design axial resistance N_Rd = reduction factor × (f_pk/γ_m) × A + reinforcement contribution = 0.79 × (9/2.0) × (290 × 290) × 10⁻³ + reinforcement term ≈ 320 kN.
Utilization: N_Sd / N_Rd = 245 / 320 = 0.77.
What Governs, and Why
The combined slenderness-eccentricity reduction factor governs the column's real usable capacity at utilization 0.77, cutting roughly 21% off the column's zero-slenderness nominal capacity — a reduction broadly consistent in magnitude with the Eurocode 6 masonry column example elsewhere in this series at a similar slenderness ratio, underscoring that despite different code formulations, the underlying structural penalty for slenderness in masonry columns lands in a comparable range across codes.
Where Structyze Takes Over
Every check above runs automatically inside the Structyze Masonry Column / Pier module — this particular module is part of the full desktop catalogue rather than the free browser trial, since the trial only carries a curated flagship set. You can still try the free trial modules right now to see the same calculation style in action on RCC Beam, Column, Slab and a handful of others.
For Masonry Column / Pier and the rest of the full catalogue — 80+ components across RCC, Steel, Composite, Timber, Masonry and more, across 20+ design codes — buy the full Structyze desktop app or see everything it does on the Software page.
Quick FAQ
Does NBR 16868 require fully grouting a column, or can partially grouted columns be designed too?
Partially grouted masonry columns are permitted under NBR 16868 with correspondingly reduced effective section properties reflecting only the actually-grouted area, though fully grouting a column carrying significant axial and moment demand, as in this example, is common practice to maximize both strength and stiffness.
Is the reinforcement's contribution to axial capacity significant in a reinforced masonry column?
It contributes, but for typical reinforcement ratios in masonry columns (modest compared to RCC column reinforcement ratios), the masonry itself still provides the large majority of axial capacity, with reinforcement playing a proportionally larger role in flexural and ductility behavior than in pure axial capacity.
Final Thoughts
Comparing this NBR 16868 column against the Eurocode 6 example elsewhere in this series at a similar slenderness shows the two codes landing in a similar reduction range despite entirely separate formulations — a useful sanity check that both are capturing the same real masonry buckling behavior, just through their own calibrated bookkeeping.