Identification of Cracks

Ans 1

1A-

Observation

1. Concrete crushed and the reinforcement is exposed.
2. Concrete spalled beyond the reinforcement which may be a sign of rupture
3. Beam top portion looks safe because of the flange advantage from slab
4. The cracks develops from bottom to top means rebar yeilding occurs in support bottom only.

Ans

• Its form of flexural failure due to reversal of stress during earthquake
• During stress reversal, support top experiences compressions and bottom experience tension
• Top compression is managed by slab advantage. bottom tension was not satisfied by the provided reinforcement
• Since the reinforcement got yielded it can not be repaired

1B

Observation

1. Cracks along the beam- column edge
2. Cracks seems to have developed through thr structurw as it looks wider
3. Beam looks separated from the column at joints.
4. Concrete is not severely crused.

Answer

• Its beam Pull out failure due to insufficient development length of reinforcement in joint
• During the earthquake the horizontal movement of structure makes this condition worse and detached the beam member from column
• Providing anchorage length between two existing concrete is very difficult. So not repairable.

1C

Observation

1. Cracks are exactly at the joint of columns and beams
2. Cracks in beam developed through its entire width
3. Slabs also developed more cracks along the beam width direction

Answer

• Its a plastic hinge failures
• 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 handel the Tension but unable to control the damage
• The joint can strengthened.

Ans 2

2A

Observation

1. Concrete damages at top of column.
2. Concrete damaged all around the column face
3. Beam are safe
4. The location of column looks at edge of the building

Answer

• Its a soft storey failure, technically plastics hinges formation
• Due to absence of infill walls at GF the plastic hinge form at the top of ground atorey column during lateral movement
• Based on the development of crush of concrete it can either be repairable or non repairable

2B

Observation

1. Concrete developed complete breakage diagonally
2. Longitudinal reinforcement are intact
3. Shear reinforcement spacing looks wider

Answer

• Its a Pure shear failure
• Inadequate shear reinforcement compels concrete takes all the shear stress.

2C

Observation

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 might be a post failure support after columns failed providing temporary prop to avoid the collapsed of the entire structure

Answer

• Its a short column failure
• An additional slab or beam connected to a column in mid height leads to this effect
• This lead to failure especially if the connection is unintentionally and not accounted in design
• The failure given in the picture is not at all repairable.