Question

What are the possible failures of an insufficient column baseplates subjected to axial load and moment.

Answer 1

The predominant failure modes of the
insufficient column baseplates include: yielding of the base plate on the compression side, crushing of concrete, and shear
failure due to sliding of the base plate and bearing failure of the shear lugs against the adjacent concrete.

In case of both axial load and moment the possible failure mode can be:

1.Flexural Compression Failure

A reinforced column that subjected
combined axial load and bending moment
reaches capacity when concrete reaches the
ultimate deformation level as about 0.003~0.0035.
If concrete reaches the deformation capacity
before yielding of longitudinal reinforcement
bars in tension region, the failure mode is called
as compression dominant flexure failure.

2. Shear and Tortion Failure
Shear and torsion failure after inelastic cyclic
loading is often observed in RC beam or column
whose shear strength is slightly larger than its
flexural strength.