Practical + Tips)

Short columns fail primarily by **crushing** rather than buckling. The allowable load is calculated using:

Here, σ_allow is the permissible compressive stress (material dependent) and A is cross-section area. For concrete (f_ck=25 MPa), σ_allow ≈ 0.4 × f_ck.

Eccentric loading induces **bending stress** in addition to axial stress. Combined stress is given by:

Even small eccentricities must be considered in design (IS 456 assumes a minimum eccentricity).

Base plates spread column load to foundation concrete. The plate area is:

Check plate bending thickness per IS 800/ACI guidelines after computing plate area.

For slender columns, Euler’s buckling load applies:

End condition factor (K): Fixed-Fixed=0.5, Fixed-Free=2.0, Pinned=1.0, Fixed-Pinned=0.7.

Limit State Design formula per IS 456:2000:

This combines concrete and steel capacities ensuring ductile behavior.

ASD design uses:

For slenderness ratio λ < 180. Reference AISC/IS 800 charts for allowable stresses.