Identification of Cracks

What is the mode of failure or damage of the beams in the figure above? Would you characterize the case as damage or as a failure? Are the damages repairable? Elaborate.

QUESTION-01

(Answer):

A)

Observations:

1. Concrete crushed and the reinforcement is exposed.
2. Concrete spalled beynod the reinforcement which may be a sign of rupture.
3. Beam top portion looks safe beacause the flange advantage slab.
4. The crack develops from bottom to top means rebars yielding occurs in support bottom only.

Solutions:

1. Its form of flexural failure due to reversal of stress during earthquake.
2. During stress reversal, Support top experiences Compression and Bottom experiences tension.
3. Top compression is managed by Slab advantage. Bottom tension was not satisfied by the provided reinforcement.
4. Since the reinforcement got yielded, it can not be reparied.

B)

Observations:

1. Cracks along Beam-Column edge.
2. Cracks seem to have developed through the structure as it looks much wider.
3. Beam looks speparated from the column at joints.
4. Concrete is not severely crushed.

Solutions:

1. Its Beam pull out failure due to insufficient developemnt length of reinforcement in Joints.
2. During earthquake, The horizontal movement of structure makes this condition worse and detached the beam member from column.
3. Providing anchorage length between two existing concrete is very difficult. So not repairable.

C)

Observations:

1. Cracks are exactuly at the joint of Column-Beam.
2. Cracks in beam developed through its entire width.
3. Slab also developedd more cracks along the beam width direction.

Solutions:

1. It's a Plastic hinge failure.
2. The damage occurred only in the joint zone first of all.
3. Cyclic lateral loading & stress reversal at the joints led to the damage.
4. Even the slab participated to its best to handle the Tension ( Salb is severely craked means it has undergone tension with its flange condition), But unable to control the damage.
5. The joint can be strengthened.

QUESTION-02

(Answer):

A)

Observations:

1. Concrete damaged at top of a Column.
2. Concrete damaged all around the Column face.
3. Beams are safe.
4. The location of column looks at edge of the building.
5. No walls are built along the column means it is probably at Ground floor, for Parking Car movement access.

Solutions:

1. It's a Soft storey failure, Technically Plastic hinge formation.
2. Due to absence of Infill walls at the Ground floor, The plastic hinge forms at the Top of ground storey columns during Lateral movement.
3. Based on the development of crush of concrete, it can either be repairable or Non-repairable.

B)

Observations:

1. Concrete developed complete breakage diagonally.
2. Longitiuddinal reinforcements and intact.
3. Shear reinforcement spacing looks wider (which means probably lesser shear rebar provided).

Solutions:

1. It's a Pure Shear failure.
2. Inadequate shear reinforcement comples concrete takaes all the shear stresses.

C)

Observations:

1. Column failed completely.
2. Failure at top of column.
3. There are two slabs connected to the column, Probably one at mid height of the column.
4. The wooden piles migth be a Post faiure support aftter column failed, providing temporary prop to avoid collapse of the entire structure.

Solutions:

1. It's a Short Column failure.
2. An additional slab or a beam connected to a Column in mid-heigth leads to this effect.
3. This leads to failure especially if the connection is unintentional and not accounted in design.
4. The failure given in the picture is not at all repairable.