Identification of Cracks

1.a)

OBSERVATION:

          Concrete crushed and the reinforcement is exposed on the image.Concrete spilled beyond the reinforcement which may be a sign of repture.Beam top portion looks a safe beacause of the flange advantage from the slab.The crack develops from bottom to top means rebar " yielding "will occurs in the support bottom only.

ANSWERS:

          It's form of Flexural failure due to reversal of the stress during earthquake.During stress reversal,Support to the top and Bottom experiences will Tension occurs.When the failure occurs the" Top compression " is managed by Slab and  " Bottom tension " was not satisfied with the reinforcement how much we provided.Since the reinforcement got yielding , it can not be repaired.

1.b)

OBSERVATION:

          The cracks will form on Beam and Column of the edges.When the cracks get deeper and bigger that's the reason only we getting structure their size is bigger.Beam looks seperated from the column at the joints.That not severely crushed the concrete.

ANSWERS:

          It's beam pull out of failure due to insufficient development length of the reinforcement on joints.During earthquake,The foundation of the structural building it makes weeker and it seperate the beam as structural elements.Now the work between the two concrete is very difficult to place the Anchorage,so it is not a repairable.

1.c)

OBSERVATION:

          The cracks will be presented at exact point of the joints at column and beam.It will develop the Cracks and width of the Beam.Slab also developed more cracks along the beam width direction.

ANSWERS:

          It's a plastic hinge failure.First of all the joint areas will occurs the damages.Cyclic lateral loading and the stress will be reversel at the joints led to the damage.Even the slab particpated to it's best to handle the tension,But unable to control the damage.The joints can be strengthened.

2.a)

OBSERVATION:

• Concrete will be damaged at the top of a column.
• Concrete damage all around the column face.
• Beams are safe.
• The location of column look at the deges of the building.
• No wall are built along the column means it is probably at the ground floor , for parking car movement access.

ANSWERS:

• It's a soft stoery failure,Technically plastic hinge formation.
• Due to absewnce of infill walls at the ground floor, The plastic hinge forms at the top of ground storey columns during lateral movements.
• Based on the development of crush of concrete it can either be repairable or Nn-repairable.

2.b)

OBSERVATION:

• Concrete will developed the complete breakage diagonally.
• Longitudinal reinforcement are intact.
• Shear reinforcement spacing looks winder.

ANSWERS:

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

2.c)

OBSERVATION:

• Column failed is 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 wodden piles might be a post failure support after column failed , providing temporary prop to avoid collapse of the entire structure.

ANSWERS:

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