Identification of Cracks
1. a) OBSERVATION
The concrete crushed and the reinforcement is exposed.
It may be a sign of rupture.
The beam top portion looks safe because of the flange advantage from the slab.
There is no crack or no severe issues are found at the top of the beam
The reinforcement is still active at the support.
It’s a form of flexural failure due to reversal of stress during earthquake.
ANSWER:
Because during the stress reversal, support top where usually tension is taking place.
The structure will feel compression during an earthquake. And at bottom, it experiences tension. Top compression actually is managed by slab because the slab has concrete.
The T-action of the beam has tried to manage the excess compression, but the bottom tension was not satisfied by the provided reinforcement.
If the reinforcement got yielded, it cannot be repaired.
b) OBSERVATIONS
Cracks along beam column.
We can see the cracks along the beam line and along with column line
And the crack seems to have development through the structure as it looks much wider.
Width of the cracks will be much wider and that cracks would have developed through the column or the Beam.
The beam looks separated from the column at joints.
The concrete has not crushed, but it does crack.
ANSWER:
It's been pulled failure due to insufficient development length of reinforcement in the joints.
During earthquake the horizontal Movement of the structure makes this condition worse and it detached the beam member from the column because the sufficient development length helps the beam develop sufficient bond with the supporting member.
If the anchorage of reinforcement is not sufficient, and inadequate reinforcement at the beam column joint. The lateral movement cannot be satisfied, so the beam ultimately getting detached from the vertical member. So providing Anchorage between two existing, concrete is very difficult. the both elements or existing concretes and development are achieving, the encouragement between these two existing concrete is very difficult, so it cannot be repaired.
c) OBSERVATIONS :
Cracks or exactly at the joint of column beam.
The cracks in beam developed through its entire width.
The cracks At the joint Actually, at the face of the beam it has developed from this side to the deck that side.
Then slab also developed a more cracks along the beam width Direction.
carefully look into the picture, You can see the cracks are random cracks are developed in the slab area
ANSWERS
It’s a plastic hinge, failure, usually plastic hinges, failure or happening at the joints, only.
So the damage occurred only in the joint Zone, So, that's the main reason why we conclude it as a plastic in failure.
And cyclic lateral loading and stress reversal at the joints, led to this damage.
Even the slab participated to its best to handle the tension. Because slab is securely cracked that means it undergoes tension but unable to control the damage, even the flange advantage of the slab.
The slab with the advantage was unable to control the damage.
The joint can be strengthened, it's not look much critical one so it can be strengthened
2.a) OBSERVATIONS:
The concrete damaged at top of column, and damaged all around the column face. So it's not at one side.
The falling of concrete had occurred, all around the column.
The beams are safe.
The beam doesn’t undergo any issues or crack or any spalling of concrete portions at all.
And the location of column looks at edge of the building. See, this is a looks a external environment like because it looks brighter, whereas this one will be an interior one. So definitely this column would be an external column for sure. And no walls or built along the column means it is probably a ground floor for parking car moment axis. Because we see no partition walls are connected at the front of the column. So definitely there should be an opening and the opening at ground floor is usually for an entrance for the public access or the car moment for parking in and out.
ANSWER:
It’s a soft storey failure. Technically plastic Hinge formation at column. So, due to absence of infill walls, at the ground floor, the plastic hinge forms at the top of the ground storey columns, during the lateral moment because of the mass irregularity.
Based On the development of the crush of concrete, it can either be repairable or non-repairable based on the severity of the column spalling only, we can control whether it is repairable or not
b) OBSERVATIONS:
Concrete developed complete breakage diagonally.
There is no crack or it's completely crusted. It's completely detached.
And the longitudinal reinforcements are the intact; the longitudinal main reinforcements of the column are not so damaged.
The shear reinforcement spacing looks wider.
Lesser shear reinforcement is provided.
ANSWER:
it's a pure share failure because the crack is in diagonal Direction.
The complete concrete had crashed and they have detached.
The shear reinforcement was not sufficient.
c) OBSERVATIONS:
Column failed completely there is no single Bonding between the upper column and the lower column.
Failure at top of column. And there are two slabs connected to the column. one at mid height of the column.Slab connected to this column. And because it's not a floor to floor height. it will be some other slab. For example, any Mid Height, similarly, for any landing for the staircases or any service levels where no man or Public accesses allowed, only something or mechanical equipment are placed for that kind of purpose. They may have added one more intermediate slab between the columns. So, and then, the wooden piles might be a post failure, support after column failed. So providing temporary prop to avoid collapse of the entire structure. So we should not account this supports. These are like bamboo and these are actually temporary supports to the beams because the beam had lost the support from the column. So it should be temporarily supported to avoid Collapse.
ANSWER :
It’s a short column failure. Intermediate slab connected with same column, which is so long and the internal columns or not that height. They're nearly half and this kind of columns where the internal intermediate slabs are connected. They will be subjected to heavy Shear Force. So an additional slab or a beam connected to a column in mid height leads to this effect. This leads to failure especially if the connection is unintentional and not accounted in design. The failure given in the picture is not at all repairable.