Axial load plus bending with minimum eccentricity and ties.
Columns carry axial load and moment: P_u=0.4f_ckA_c+0.67f_yA_sc (short, axially loaded). Slenderness effects for L_eff/D>12. Longitudinal steel 0.8–4% of area; ties at limited spacing confine concrete. Interaction diagrams show combined axial-moment capacity.
A 400×400 column with 8 bars of 25 mm carries about 3000 kN.
Columns carry axial load and bending together, so their design must consider slenderness, minimum eccentricity and detailing.
Axial load plus bending with minimum eccentricity and ties.
Columns carry axial load and bending together, so their design must consider slenderness, minimum eccentricity and detailing.
A small allowance for unavoidable offsets in the load, which ensures the column is designed for some bending even when the load is nominally axial.
A high ratio of effective length to radius of gyration, which increases the risk of buckling and needs an additional check.
Typical applications include designing a short concrete column for a building frame, checking the slenderness of a tall column in a car park and placing the starter bars and links for a column in the foundations.
Study "Design of RC slabs" first (topic 53 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
Short vs slender columns. Spirals. Minimum eccentricity.
A 400×400 column with 8 bars of 25 mm carries about 3000 kN.
The next topic is "Development length and detailing", which builds directly on this one.
It is classed as Intermediate in Civil & Structural (topic 54 of 112). It is an intermediate topic. Work through the beginner topics in Civil & Structural first.
Want to practise? Open the interactive course for quick checks, quizzes, simulations and progress tracking.