RCC Columns – Minimum Diameter of Lateral Ties What is the minimum diameter permitted for lateral ties (column ties) in reinforced concrete columns under standard detailing practice?

Introduction / Context:
Lateral ties in columns confine the core concrete, restrain longitudinal bars from buckling, and maintain reinforcement geometry during casting. Codes specify a minimum diameter to ensure adequate stiffness and robustness of ties, especially during vibration and handling.

Given Data / Assumptions:

• Member: reinforced concrete column.
• Role of ties: confinement, bar restraint, and geometry control.
• Standard practice: non-seismic, ordinary detailing context.

Concept / Approach:

The minimum tie diameter must be sufficient to avoid yielding or distortion during placement and service. Standard practice sets an absolute lower bound along with a conditional rule that ties should not be less than one-fourth of the largest longitudinal bar diameter; however, the absolute minimum remains a fixed value in millimetres.

Step-by-Step Solution:

Verification / Alternative check:

Typical bar bending schedules and standard RCC detailing textbooks prescribe 6 mm as the minimum tie diameter in ordinary conditions, while seismic detailing often increases this (for example to 8 mm) in special confining regions.

Why Other Options Are Wrong:

• 4 mm and 5 mm: Too slender for reliable confinement.
• 10 mm: Allowed, but not the minimum; used in heavily loaded columns or seismic regions.

Common Pitfalls:

Confusing seismic provisions with general detailing; ignoring the one-fourth largest bar rule that can govern when main bars are large.

Final Answer:

6 mm