Challenge

Identification of Cracks

1. Aim: To explain about the mode of failure or damage of the beams in the given figure and are the damages are repairable.

Introduction: To explain about the mode of failure or damage of the beams in the given figure and are the damages are repairable.

Procedure:

A. Observations:

In the figure we can see that the concrete has damaged more than the damaged level and we can see the reinforcement also.
Concrete crushed and the reinforcement is exposed.
Concrete spalled beyond the reinforcement which may be a sign of rupture.
Beam top portion looks safe because of the flange advantage from the slab.
The crack develops from bottom to top means rebar yielding occurs in support bottom only.
The reinforcement is still active at the top.

From these observations we can conclude that

Its form of flexural failure due to reversal of stress during earthquake.
During the stress reversal, support top experiences compression and bottom experiences tension.
Top compression is managed by slab advantage because the slab has concrete but the bottom tension was not satisfied by the provided reinforcement.
So that the bottom reinforcement has yielded and it cannot be repaired.
And it leads to the crushing of the concrete at the bottom.

B. Observations:

From these observations we can conclude that

Its beam pull out failure due to insufficient development length of reinforcement in joints.
During earthquake, The horizontal movement of the structure makes this condition worse and detached to the beam member from the column.
Providing anchorage length between two existing concrete is very difficulty. So it is not repairable.

C. Observations:

From these observations we can conclude that

It is a plastic hinge failure.
The damage occured only in the joint zone first of all.
Cyclic lateral loading & stress reversal at the joints led to the damage.
Even the slab participated to its best to handle the tension (Slab is severly cracked means it has undergone tension with its flange condition) But unstable to control the damage.
The joint can be strengthened.

2. Aim: To explain about the mode of failure or damage of the beams in the given figure and are the damages are repairable.

Introduction: To explain about the mode of failure or damage of the beams in the given figure and are the damages are repairable.

Procedure:

A. Observations:

Concrete damaged at the top of the column.
Concrete damaged all around the column face.
Beams are safe.
The location of column looks at edge of the building.
No walls are built along the column beams it is probably at the ground floor, for parking car movement access.

From these observations we can conclude that

It's a soft storey failure, Technically Plastic hinge formation.
Dut to absence of infill walls at the Ground floor, The plastic hinge forms at the top of ground storey columns during lateral movement.
Based on the development of crush of the concrete, it can either be repairable or Non-repairable.

B. Observations:

Concrete developed complete breakage diagonally.
Longitudinal reinforcements are intact.
Shear reinforcement spacing looks wider (which means probably lesser shear rebar provideed).

From these observations we can conclude that

C. Observations:

Colums failed completely.
Failure at the top of the column.
There are two slabs connected to the column, probably one at the mid height of the column.
The wooden piles might be a post failure support after column fialed, providing temporary prop toavoid collapse of the entire structure.

From these observations we can conclude that

It's a short column failure.
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 below picture is not at all repairable.

Ship work like this
in your own course.