ANS:D - 50

In structural engineering, the slenderness ratio (λ) is a measure of how slender or "long" a structural member is relative to its cross-sectional dimensions and its ability to resist buckling under compressive loads. For reinforced concrete columns, the slenderness ratio is typically defined as the ratio of the effective length (l) to the least lateral dimension (d) of the column. The slenderness ratio (λ) is calculated using the formula: λ=l/d​ Where:

• λ = Slenderness ratio
• l = Effective length of the column
• d = Least lateral dimension of the column (diameter for circular columns, smallest width or depth for rectangular columns)

An RCC (Reinforced Concrete) column is considered "long" if its slenderness ratio exceeds a certain threshold value. This threshold value depends on the structural analysis and design criteria, as well as the specific design code or standards being used. Among the options provided—30, 35, 40, 50, and 60—the most commonly accepted threshold value for considering an RCC column as "long" is typically around 30 to 40. However, the specific value can vary depending on factors such as the material properties, loading conditions, and design codes. In many design codes, including the Indian Standard IS 456:2000 for reinforced concrete design, a slenderness ratio greater than 30 is often used to classify a column as "long." Therefore, the correct answer based on common engineering practice and design standards is: Slenderness ratio>30Slenderness ratio>30 However, it's important to note that the specific threshold value may vary depending on the design criteria and standards applicable to the project.