Select the correct comprehensive statements for reinforced concrete columns regarding steel percentage, minimum number of longitudinal bars, helical reinforcement, and the pedestal definition based on effective length.

Difficulty: Easy

Only statements (1) and (2) are correct.
Only statements (2) and (3) are correct.
Only statements (3) and (4) are correct.
All the above.
Only statements (1) and (4) are correct.

Correct Answer: All the above.

Explanation:

Introduction / Context:
Design and detailing rules for columns cover steel percentage limits, minimum number of bars, and special reinforcement such as helical ties. Additionally, members with very small effective lengths relative to their lateral dimensions are categorized differently (as pedestals) because slenderness effects are negligible. This question bundles several fundamental rules typically recalled from RCC design codes and handbooks.

Given Data / Assumptions:

(1) Longitudinal steel percentage limits relative to gross area.
(2) Minimum bar count for rectangular and circular columns.
(3) Minimum bar count when helical reinforcement is used.
(4) Pedestal identification based on effective length to lateral dimension ratio.

Concept / Approach:
Columns must ensure adequate ductility and load transfer through a reasonable distribution of longitudinal bars. Minimum percentages and bar counts prevent reinforcement from being too sparse; maximum limits avoid congestion. Helical reinforcement improves confinement but still requires a minimum number of longitudinal bars. Short stocky members are treated as pedestals, simplifying design against buckling.

Step-by-Step Solution:

(1) Minimum and maximum longitudinal steel: not less than 0.8% and not more than about 4% of gross area for practical design (though absolute maxima may be higher, practice often caps near 4%).(2) Minimum bars: rectangular columns ≥ 4 bars; circular columns ≥ 6 bars.(3) Helically reinforced columns: retain a minimum of six longitudinal bars.(4) Pedestal definition: effective length < 3 times the least lateral dimension → treated as a pedestal.

Verification / Alternative check:

These rules are ubiquitous across RCC exam guides and align with typical provisions that promote ductility and mitigate accidental eccentricities.

Why Other Options Are Wrong:

Any subset option omits a correct statement; all four listed statements are jointly correct in the standard exam context.

Common Pitfalls:

Mixing up column limits with beam limits; forgetting that circular columns require more bars to maintain spacing and symmetry.

Final Answer:

All the above.

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Select the correct comprehensive statements for reinforced concrete columns regarding steel percentage, minimum number of longitudinal bars, helical reinforcement, and the pedestal definition based on effective length.

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