Q1: An R.C.C. column is treated as short column if its slenderness ratio is less than

ANS:D - 50

A short column is one in which the effect of slenderness (the tendency to buckle under compressive loads) is minimal compared to the effect of the column's material properties. In concrete columns, this typically means that the column's effective length is relatively small compared to its cross-sectional dimensions, resulting in a low slenderness ratio. The slenderness ratio (L/r) is the ratio of the effective length (L) to the least radius of gyration (r) of the column's cross-section. The effective length is the distance between points where the column is effectively prevented from moving or rotating, such as between floor slabs or bracing points. The least radius of gyration is a measure of the column's resistance to buckling about its weak axis. When the slenderness ratio is less than a certain critical value, which is typically around 12 for concrete columns according to general design guidelines, the column is considered short. This means that the column's behavior is primarily governed by its material properties and strength, rather than by buckling considerations. In summary, a slenderness ratio less than 12 indicates that the column is short, while a slenderness ratio greater than 12 suggests that the column may behave as a long column and requires special consideration for buckling effects in its design.