Test: Columns - 1 - Civil Engineering (CE) MCQ

Effective length of a column depends upon:
(i) Flexural stiffness (El/L) of beams joining at a point.
(ii) Flexural stiffness (El/L) of columns joining at a point.
(iii) Type of frame (sway or non-sway).

In the working stress method the design of a long column is made by considering reduced stresses obtained by multiplying the permissible stresses by a coefficient,


= 0.85 or 0.92
So the reduction coefficient is 0.85

Maximum reinforcement = 6%
Minimum reinforcement = 0.8%

Ratio = 6/0.8 = 7.5

Very short columns with effective length less than three times least lateral dimension are called pedestal columns.

The shear force should be calculated at critical section i.e. 1 m away from the face of the column. Effective span of beam is to be taken as the clear span plus effective depth of beam or centre to centre spacing of supports which ever is less. The location for shear calculation will be,
x = 0.25 + 1 = 1.25 m
∴ Design shear force = (10 x 10)/2 - 10 x 1.25
= 37.5 MN

As per IS : 456-2000 clause 26.5.3.1 (a) the minimum number of longitudinal bars provided in a column shall be four in rectangular columns and six in circular columns.

Minimum eccentricity equals to unsupported length of column/500 plus lateral dimension/30, subject to a minimum of 20 mm.

So eccentricity = 20 mm