Identification of Cracks

1(a)

observations :

concrete crushed and the reinforcement is exposed

Answer:

Its form of Flexural failure due to reversal of stress during earthquake.

During stress reversal , Support top experiences compression and bottom experiences tension

1(b)

observations :

Cracks along beam column edge

Cracks seem to have developed through the structure as it looks much wider.

Answer :

Its beam pull out failure due to insufficient development length of reinforcement in joints

During earthquake. The horizontal movement of structure makes this condition worse and detached the beam member from column.

1(c)

Observations :

Cracks are exactly at the joint of column beam.

Cracks in beam developed through its entire width

Answer:

Its a plastic hinge failure

The damage occured only in the joint zone first of all

2(a)

Observations:

Concrete damaged at top of a column.

Concrete damaged all around the column face.

Answer:

Its a soft storey failure, Technically Plastic hinge formation.

Due to absence of infill walls at the ground floor. The plastic hinge at the top of ground storey columns during lateral movement.

2(b)

Observations :

Concrete developed complete breakage diagonally.

Longitudinal reinforcements are intact.

Shear reinforcement spacing looks wider

Answer :

Its a pure shear failure

Inadequate shear reinforcement compels concrete takes all the shear stresses.

2(c)

Observations :

Column failed completely

Failure at top of column

Answer :

Its a short column failure

An additional slab or a beam connected to a column in mid height leads to this effect.