Identification of Cracks

AIM: To observe What is the mode of failure or damage of the beams in the figure above? Are the damages repairable? a) b) c)
OBSERVATION:
a) Concrete is crushed and reinforcement exposed.
concrete spalled beyond the reinforcement which may be sign of rupture.
Beams top looks safe because of flange advantage from slab.
Damage occurs from bottom to top which means rebar yeilding occurs in bottom only.
b) Cracks along beam column edge.
Cracks seems to have developed through the structure as it looks much wider.
Beams look separated from column at joints.
concrete is not severly crushed.
c) Cracks are exactly at the column beam joint.
Cracks in beam has developed through its entire width.
Cracks have developed through the slabs along the beam width direction.
RESULT:
a) It is the form of Flexural failure due to reversal of stress during earthquake.
Due to reversal support top experiences compression and bottom experiences tension.
Top compression is managed by slab advantage. Bottom reinforcement is not satisfied by provided reinforcement.
since the reinforcement got yeilded it cannot be repaired.
b) Its a beam pull out failure due to unsufficient developement length of reinforcement in joints.
During earthquake the horizontal movement of the structure makes the condition worse and detached the beam member from the column.
Providing anchorage between two existing concrete member is not possible. so not repairable.
c) Its a plastic hinge failure.
The damage has occured only in the joints.
Cyclic lateral loading and stress reversal in joints has led to this damage.
Even the slab participated to its best( severe cracks can be seen in slabs which means the slab has experienced tension with its flanged condition ) to hold the damage.
The joint can be strengthened.

AIM: To observe What is the mode of failure or damage of the beams in the figure above? Are the damages repairable?
a) b) c)
OBSERVATION:
a) Concrete damaged at the top of the column.
Concrete is damaged at all faces.
Beams are safe.
The location of the Column is at the edge of the building.
No walls around the column which means it is the ground floor used for parking etc.
b) Concrete developed complete breakage diagonally.
Longitudnal reinforcements are intact.
Shear reinforcements spacing looks wider(which means probably lesser shear rebars provided).
c) column failed completely.
failure at the top of column.
Two slabs connected to the column one at the mid and other on the top.
The wooden piles are provided post failure for temporary support to avoid complete failure.
RESULTS:
a) Its a soft storey failure.Technically, plastic hinge formation.
Due to abscence of fill wals in the ground floor the columns develop plastic hinge at the top of the column during lateral movement.
As per the crushed concrete it can be repaired or not repaired.
b) Its a pure shear failure.
Inadequate shear rebars compels concrete takes all the shear stresses.
c) Its a short column failure.
An additional slab to the column leads to this kind of effect.
It leads to failure especially if the slab is unintentionall and not accounted in the design.
The failure in the picture is not at all repairable.