Identification of Cracks

Identification of Cracks

Jagadeep.M.M

AIM:

To identify the model of failure or damage of the beames in the given figure.

Observations:

• Concrete crushed & 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 slab.
• The crack develops from bottom to top means rebar yielding occurs in support bottom only.

Ans:

• Its form of fexural failure due to reversal of stress during earthquake.
• During stress reversal, support top experiences compression & bottom experiences tension.
• Top compression is managed by salb advantage. Bottom tension was not satisfied by the provided reinforcement.
• Since the reinforcement got yielded, it cannot be repaired

1b)

AIM:

To identify the model of failure or damage of the beam-column edge in the given figure.

Observations:

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

Ans:

• Its beam pull out failure due to insufficient development lenght of reinforcement in joints.
• During earthquake, the horizontal movement of strucrure makes this condition worse & detached the beam member from column.
• Provideing anchorage lenght between two existing concrete is very difficult, So not repairable.

1c)

AIM:

To identify the model of failure or damage of the column beam joint in the given figure.

Observations:

• Cracks are exactly at the joint of column Beam.
• Cracks in Beam developed through its entair width.
• Slab also developed more cracks along the beam width direction.

Ans:

• It's a plastic hinge failure.
• The damage occurredonly 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 severely cracked means it has undergone tension with its flange condition), Butunable to control the damage.
• The joint can be strengthened.

2(a)

AIM:

To identify the model of failure or damage at the top of the column in the given figure.

Observations:

• Concrete damaged at top of a column.
• Concrete damaged all around the column face.
• Beam are safe.
• The location of column looks at edge of the building.
• No wall are built along the column means it is probably at groung floor, for parking car movement access.

Ans:

• It's a safe sory failure, Technically plastic hinge formation.
• Due to absence of infill walls at the Ground floor, the plastic hinge forms at the top of ground story columns during lateral movement.
• Based on the development of crush of concrete, it can either be repairable or non-repairable.

2b)

AIM:

To identify the model of failure or damage of the beams which is completely breakage in the given figure.

Observations:

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

Ans:

• It's a pure shear failure.
• Inadequate shear reinforcement compels concrete takes all the shear stresses.

2c)

AIM:

To identify the model of failure or damage of the column in the given figure.

Observations:

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

Ans:

• It's a short column failure.
• An additional slab or beam connected to a column in mid-height leads to this effect.
• This leads to failure especially if the connection is unintentional & not accounted in design.
• The failure given in the picture is not at all repairable.