Challenge

Identification of Cracks

1(a).

Observation:

The concrete is crushed at the joint of the vertical support and the reinforcement of the damaged are is visible.
The spalling of cocncrete beyond the reinforcement which indicates the rupture in concrete.
The damage occures oly on the bottom of the beam and top are of the beam seems to be safe, so the rebar yielding support bottom only.

Conclusion:

Its the form of Flexural failure due to the reversal of stress due the earth quake.
During the reversal of stress the top of the beam experiences the compresion, where the bottom experiences the tension.
The compresion on the top is managed by the slab reinforcement, whereas the reinforcement in the bottom in inadequate hence the damage is formed.
Since the reinforcement id yeilded the damage cannot be repaired.

1(b).

Observation:

The crack seems along the edge of the beam and column, but the structure is only cracked not crushed.
The crack is along the structure of thge beam colum nas the crack gets bigger.
And the beam structure seems to be detached from the vertical support (column).

Conclusion:

This is concluded as Beam pull-out failure.
This happen due to the inadequate reinforcement of devolepment length in the joints.
The adequate devolepment length at the joint devolep the sufficient bond between the beam column.
If the bond between the beam and supporting structure(column) is inadequate, then bond can be easily broken by the lateral movement(eartquake).
Providing additional DEVOLEPMENT length to the reinforcement at the join is a easy task.
But providing the same devolpment length on two existing concrete structure is very hard, so the repair is not possible.

1(c).

Observation:

Here, the cracks are right on the joints of the beam-column.
The cracks are devoleped to the entire face of the beam.
Some minor random cracks are visible on the slab aswell as the continued from the joints.

Conclusion:

This is considered as the Plastic Hinge Failure.

These occur only on the joint hence it is plastict hinge failure.

This is caused by the cyclic lateral loading or the stress reversal at the joint which causes the damage.

The cause of the cracks in the slab indicates the, slab also influenced by the lateral movement, but the slab couldn't withstand the damage.

Since the crack is not huge or have no visible reinforcement, it can be strengthened and repaired.

2(a).

Observation:

The concrete is damaged at the top of the column.
It seems like the there are no walls built along the column.
That refers to, that the column must be on the ground floor, the opening for the movement of the cars and other vehicles.
Beams seems to be undamaged.

Conclusion:

This is concluded as the soft storey failure.
Due to the lack of infill walls the plastic hinge is formed at the top of the ground floor column during the lateral movement (earth quake).
This can be repaired based on the severeness of the damage.
If the damage is too high, that the reinforcement is visible then nothing can be done.

2(b).

Conclusion:

This is a Pure Shear Failure.
Inadequate shear reinforcement compells the concrete to bear all the shear stress.
Hence the adding stirrups is the solution, THIS CANNOT BE REPAIRED.

2(c).

Observation:

The damage is on the top of the column.
The top of the column is completely failed.
There are two slabs conected to the column, it must be the sink roof for the toilet or any other service room.
The wooden piles are provided for support for the slab from collapsing, since it has no support.

Conclusion:

This is the Short Column Failure.
Since the 2 slabs ared connected to the column at its mid height.
The column becomes the short column.
This kind of columnsa re to be accounted in the design and trhe reinforcement are to be designed in an manner where the joints of the column are not influenced by the lateral movement to the failure.
There is no way this failures can be Repaired.

Ship work like this
in your own course.