Identification of Cracks

Question 1-

Aim- What is the mode of failure or damage of the beams in the figure above? Are the damages repairable?

Answer-

a) Observations- Concrete surface is damaged and reinforcements are exposed. It is seen that the concrete is ruptured. Only beam bottom is severely damaged whereas the top of the beam looks safe. The rupture occur from bottom to top that means rebar yielding occurs in support bottom only.

Explanation- It is a form of flexural failure ue to revarsal of stress during earthquake. During stress reversal, the top of the beam expriences compression and botttom experiences tension. top compression is managed by slab advantage and bottom tension was not satisfied by sufficient reinforcement.

Rectification- Since the reinforcement got yielded it cannot be repaired.

b) Observations- Cracks along the beam column edge.. the cracks are much wider and deep. Concrete is not severely damaged

Explanation- The damage occured due to insufficient development length of reinforcement joints. During earthquake the horizontal movement of structure makes the condition worse and detached the beam member from column.

Rectification- Providing anchorage length between two existing concrete is very difficult, hence it is not repairable.

c) Observations- Cracks are at the joints of the beam- column and the cracks are developed through the entire width.

Explanation- It is a plastic hinge failure. cyclic lateral loading and stress reversal at the joints led to the damage. Cracks are even occured in the slab.

Rectification- The joints can be rectified by strentening.

Question 2-

Aim- What is the mode of failure or damage of the beams in the figure above? Are the damages repairable?

Answer-

a) Observations- Concrete damaged at the top of column and all around the surface of the concrete. No damaged to the beam is seen.

Explanation- Its is soft storey failure aslo a plastic hinge formation. Infill wall between two executive columns could have reduced the chances of this damage\

Rectification- Based on the crush of concrete it can be either repairable or non repairable.

b) Observations- Concrete has been completely damaged. longitudinal reinforcement are undamaged. This damaged occured due to shear failure.

Explanation- Inadequate shear reinforcement was the key for its failure.

Rectification- It is non repairable

c) Observations- Columns failed completely. Failure at the top of the column

Explanation- It is a short column failure. An additional slab or a beam connected to a column in mid height leads to this failure.

Rectification- It is non repairable.