Steel Design Sheet 31

In a grillage column footing, if a column load (W) is distributed through a column base of length (a) to the grillage beam of length (L), the maximum bending moment (M) is given by

In a grillage footing, the maximum bending moment occurs at the

The intensity of pressure between column base (of width b and length L) and concrete will be compressive throughout the length of column bar and will vary from zero to 2 P/BL, if the ratio of the moment (M) and axial load (P) is

For solid round steel column, where the load is distributed over the whole area, the minimum thickness of square base (r), as per IS : 800-1984, is given by

[Where, W= Total axial load, B= Length of the side base, d=Diameter of reduced end of the column, and ${\sigma }_b$= Allowable bending stress in steel]

If the moment due to couple in a bearing plate (of width b) is M and the allowable bending stress in slab or bearing plates is ${\sigma }_b$, then the thickness of bearing plate (t) is given by

The width of bearing plate is.... the width of the flange of column.

When upper column does not provide full bearing area over lower column, the bearing plate provided is designed by assuming that

A column base is subjected to moment. If the intensity of bearing pressure due to axial load is equal to stress due to the moment, then the bearing pressure between the base and the concrete is

Allowable working stress in compression in the column splice plates may be taken as

When the column is subjected to an eccentric load $\left(W_E\right)$ having eccentricity $e_x$ with respect of X-axis and eccentricity $e_Y$ with respect to Y-axis, then the equivalent axial load $\left(W_{EQ}\right)$ is given by

[Where, $M_X$ and Answer.