Identification of Cracks

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

a)

Observation-

• In this Picture concrete crushed & Reinforcement exposed, Concrete spalled beyond the reinforcement which may be sign of rupture.
• Beam top portion looking safe beacause advantage of flange from slab.
• The crack develops from bottom to top beacause reinforcement yielding occurs in support bottopm only.

Ans -

• It is form of flexural failure due to reversal of stress during earthquack, During stress reversal support of top experiences compression and bottom in tension.
• Top compression is manage by slab advantage and bottopm tension was not staisfied by provided reinforcement since reinforcement got yoelded .
• It can be not repairable.

b)

Obeservation -

• In this picture cracks along beam and column edge, cracks seems to have developed through the structurs as it looks much wider.
• Beam looks separated from the coloumn at joints
• concrete looking is not severely crushed.

Ans-

• In this picture beam pullout failure due to insufficient development length of reinforcement at joint.
• During earthquke the horizontal movement of structure make this condition and detached the beam from column .
• Providing anchroge length between two existing concrete is very difficult , so not repairable.

c)

Observation -

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

Ans -

• In this picture it is plastic hinge failure and damage occured only in joint zone due cylic lateral loading and strees reversal at joints .
• Even the slab participated to its best to handle the tension but unable to control thr damaged.
• Joint can be strenghthend.

2. a)

Observation-

• Concrete damaged at top of coloumn and all arround and beam is safe.
• No walls are built along the coloumn means it is probably at ground floor for parking.

Ans -

• In this image it is a soft storey failure due to plastic hinge formation.
• Due to absence of infill wall at the ground floor the plastic hinge forms at the top of ground storey columns during latral movement.
• Based on the development of crush of concrete it can be repairable.

2. b)

Observation -

• in this picture concrete developed complete breakage diagonally and longitudional reinforcement are intact.
• Shear reinforcement spacing is more , so probably less shear reinforcement provided.

Ans-

• In this picture it is a shear failure .
• Inadequate shear reinforcement completes , concrete takes all the shear stress.

2. c)

Observation -

• Coloumn failed completely at top.
• There are two slabs connected to the coloumn one at mid height of coloumn.

Ans -

• In this picture it is a short coloumn failur due to additional slab / beam connected to a column in mid height loads to this effect.
• The failure given in this picture is not repairable.