Explanation: When the line of action of the resultant compressive force doesn’t coincide with the centre of gravity of the cross section of the structure, it is called eccentrically loaded structure. They have to be designed for combined axial force.

Explanation: A vertical member whose effective length is greater than 3 times its least lateral dimension carrying compressive loads is called a column. The main function of column is to transfer the loads from the beams or slabs to the footings or foundation.

Explanation: A long column under the action of axial loads deflects laterally causing maximum deflection at the centre. A long column fails due to buckling.

Explanation: If the ratio of the effective length of the column to the least lateral dimension is less than 12. The column is called a short column. It fails by crushing (pure compression failure) and there is no chance of causing deflections.

Explanation: The column dimensions shall be such that it fails by material failure only (crushing due to compression) and not by buckling. To avoid the failure of column buckling clause 25.3 of IS 456 recommends the slenderness limits for the column.

Explanation: No column can have a perfectly axial load. There may be some moments acting due to the imperfection of construction or due to actual conditions of loading when IS 456-2000, recommends that all columns Shall be designed for minimum eccentricity of 20 mm.

Explanation: The radius of gyration about a given axis is defined as the effective distance from the given axis at which the whole area may be considered or located. It is denoted by “k” or “r”. The units for the radius of gyration are mm.

= 682.66×104mm4.

Explanation: Ductility is the property of a material by which material can be drawn into thin wires after undergoing a considerable deformation without rupture. The mild steel, silver, tor steel, aluminium etc. are considered as examples for ductility.

Explanation: The hardness is the ability of a material to resist indentation (impression), scratching or surface abrasion. It is the relative property of the material. Every material has its own hardness number.

Explanation: A set of two equal and opposite forces whose line of action is different form a couple. The effect of couple is always to produce moment on which it acts either in clockwise or anticlockwise directions. The example is rotating key of a lock.

Explanation: A body said to be in motion when it changes its position with respect to other bodies. The relative change in position is called motion. The motion involves both space and time.

Explanation: If the units are expressed in other units which are derived from fundamental units, such units are known as derived units. The examples are area, velocity, acceleration & pressure etc.

Explanation: According to IS 456-2000, the cross sectional area of longitudinal reinforcement should not be less than 0.8% and not more than 6% of gross cross-sectional area. The minimum diameter of longitudinal bars is 12 mm and minimum number of longitudinal bars to be provided is 4 for a rectangular column.