Challenge

Identification of Cracks

1(a): Mode of Failure: Flexural failure due to reversal of stress during earthquake

Observations:

Concrete is crushed and reinforcement is exposed.
Concrete spalled beyond the reinforcement which may be a sign of rupture.
The beam top looks safe because of the flange advantage from the slab.
The crack develops from bottom to top means rebar yielding occurs in the bottom only.

Result:

During stress reversal, the support top experiences compression and the bottom experiences tension.
Top compression is managed by slab advantage. Bottom tension was not satisfied by provided by reinforcement.
Since the reinforcement got yielded, it cannot be repaired.

1(b): Mode of Failure: Pullout failure due to insufficient development length of reinforcement in Joints.

Observations:

Cracks along Beam-Column edge. The crack is along the beam line and column line.
Cracks seem to be developed through the structure as it look much wider.
The beam looks separated from the column at the joints.
The horizontal member is detached from the vertical column member.
Concrete is not severely crushed.

Result:

During an earthquake, The horizontal movement of the structure makes this condition worse and detaches the beam member from the column.
Providing anchorage length between two existing concrete is very difficult.
It’s not repairable.

1(c): Mode of Failure: Plastic hinge Failure

Observations:

Result:

The damage occurred only in the joint zone first of all.
Cyclic lateral loading and stress reversal at joints led to the damage.
Even the slab participated its best to handle it, but unable to control the damage.
The joint can be strengthened.

2(a): Mode of Failure: Soft storey failure

Observations:

Concrete damaged at the top of a column.
Concrete is damaged all around the column face.
The beams are safe.
The locations of column looks at the edge of the building.
No walls are built along column means it is probably on the ground floor, for parking car movement access.

Result:

It is technically a plastic hinge formation.
Due to the absence of infill walls on the ground floor, the plastic hinge forms at the top of ground storey columns during Lateral movement.
Based on the development of crush concrete, it can either be repairable or Non-repairable.

2(b): Mode of Failure: Pure Shear Failure

Observations:

Concrete developed complete breakage diagonally.
Longitude reinforcements are intact.
Shear reinforcement spacing looks wider (which means probably lesser shear rebar provided)

Result:

2(c): Mode of Failure: Short column Failure

Observations:

Column failed completely.
Failure at the top of column.
There are two slabs connected to the column, Probably one at mid-height of the column.
The wooden piles must be post failure support after the column failed, providing prop to avoid the collapse of the entire structure.

Result:

An additional slab. or a beam connected to a. column in midheight leadsto this effect.
This leads to failure especially if the connection is unintentional and not accounted in design.
The failure given in this pivcture is not at all repairable.

Ship work like this
in your own course.