Identification of Cracks

1)a)

OBSERVATIONS:

1. In this picture we observe that concrete gets damaged/broken and reinforcement is visible at the bottom of the beam.
2. The concrete spoiled beyond the reinforcement indicates the segregation
3. The top portion of the beam is not exposed due to cover from the slab projection so, it looks safe and has no major issue/severe issue on top of the beam.
4. Cracks developed in the bottom and gradually increased towards the top. The pressure on the beam is more than its yielding point on the bottom supports but the reinforcement is still active at the support's top so there is no crck on top of the beam.

CONCLUSIONS:

1. At the time of the earthquake, the beam's stress is reversed, so this is a kind of flexural failure.
2. During the earthquake, beams get in the n tension zone and the structure feels in compression due to the stress reversal support at the top.
3. Bottom reinforcement is not sufficient to resist the tension the in beam and the top reinforcement resists the slab due to the concrete.
4. The bottom reinforcement of the beam lost there an elastic limit, so it's impossible to repair the bottom crack.

1)b)

OBSERVATIONS:

1. In the above picture, we observed the cracks developed in column-beam corners.
2. It looks like a much wider crack that has developed through the column-beam joint.
3. In this picture, the beam has separated from the column.
4. The picture shows, the concrete has not been crushed, there is only a crack developed.

CONCLUSIONS:

1. The reinforcement of the beam is not sufficient to anchor the vertical rebars of the column, that is insufficient development length of the rebar.
2. Due to inadequate reinforcement the beam is not bonded to the column that's why the horizontal member gets attached to the vertical member during the earthquake.
3. The lateral movement cannot be satisfied due to the insufficient anchorage length of beam rebar so keeps on separate from the column.
4. It is very tough to provide the development length in the casted concrete between two members, so it is not repairable.

1)c)

OBSERVATIONS:

• In this picture, we observe cracks generated in the column-beam junction.
• The cracks occurred in the entire width of the beam.
• Some cracks have developed in the slab along the direction of the beam.

CONCLUSIONS:

• This is a plastic hinge failure, the deformation in the beam means no capability to resist the moment and permit free rotation.
• The plastic hinge failure happened at the joint only, so the damage occur in the junction.
• The main reason for the damage is cyclic lateral loading and stress reversal at the junction.
• As per the image, the slab has tried to handle the tension, but still it gets cracked, so it is clear that the tension is more on the slab and the slab is unable to control the damage.
• To recover from the damage, we can strengthen the column-beam junction.

2)a)

OBSERVATIONS:

1. In this picture, we observed that the column has been damaged from the top, and the bottom of the column is safe.
2. The damage is all around the face of the column.
3. No damage was found in the neam.
4. No connected walls along the columns, so this could be the ground floor, probably the parking area.
5. It is the outer or external column of the building.

CONCLUSIONS:

1. From these observations it's clear, this is a soft storey failure, technically plastic hinge formation at the column.
2. Due to the lateral movement in the building and the absence of walls, columns got affected because of the plastic hinge formed at the upper side of the ground floor.
3. Based on the spall out of the concrete from the column and the severity of the column is to be decided as either repairable or non-repairable.

2)b)

OBSERVATIONS:

1. The breakage of concrete has diagonally developed in the column. so this is not a crack it's completely crushed and concrete detached from the column.
2. Lateral and longitudinal reinforcements are visible. Rebar has been damaged and not separated.
3. The clear vision of lateral reinforcement, i.e., shear links spacing is more than as per codel requirements which means that they have provided lesser shear reinforcement.

CONCLUSIONS:

1. By observing the picture we can conclude this is a pure shear failure because the crack is in a diagonal direction and the complete concrete had spoiled and got crushed.
2. The shear reinforcements were not sufficient so they had detached and spoiled throughout the column, it had compelled concrete to break down into the pieces.

2)c)

OBSERVATIONS:

1. From the given picture, we can observe that the column is completely failed.
2. Damage happens at top of the column anthe d bottom of the column is safe.
3. As per the picture, there are two slabs connected with the column and the space between both slabs is not the floor height so this is probably for the mechanical equipment.
4. The beam has been temporarily supported with the wooden piles after the column failure to avoid the collapse of the structure.

CONCLUSIONS:

1. From the observation we can conclude that the failure is short column failure.
2. The column is attached to an intermediate slab and the height of column is not similar to the other columns, so there is a heavy shear load on the column.
3. The intermediate slab load is unintentional and not accounted for in the design so this leads to the failure.
4. This failure is not repairable.